This document summarizes a study that used group contribution methods to predict vapor-liquid equilibrium (VLE) data for mixtures of volatile organic compounds (VOCs) and biodiesel. The study used the UNIFAC model and its modifications to predict infinite dilution activity coefficients for VOCs in biodiesel solvents at varying temperatures. The results showed that activity coefficients increased with temperature for alkanes, alcohols and acids/esters. Solubility of VOCs in biodiesel decreased with increasing biodiesel ester unsaturation and increased with increasing ester molecular weight.
This document summarizes a study that used group contribution methods to predict the solubility of volatile organic compounds (VOCs) in biodiesel. The study used three versions of the Universal Functional Activity Coefficient (UNIFAC) model to predict infinite dilution activity coefficients for VOCs in fatty acid methyl ester solvents that make up biodiesel. The results showed that activity coefficients decreased with increasing molecular weight for alkanes, amines, alkenes, organic acids, and alcohols. Shorter esters with lower carbon counts had higher activity coefficients than longer esters with higher carbon counts. Solubility of VOCs in biodiesel also decreased with increasing ester hydrocarbon unsaturation.
This document discusses various applications of quantitative structure-activity relationships (QSAR) in drug research and development. It describes how QSAR can provide information on receptor sites from enzyme inhibition studies, help understand the importance of physicochemical properties like log P values, and enable the use of bioisosterism to modify compounds. QSAR has correctly predicted drug activity and toxicity and is useful in drug design before compounds are synthesized.
Complexation and Protein Binding [Part-2](Method of analysis, Complexation a...Ms. Pooja Bhandare
This document discusses various methods for analyzing complexes, including continuous variation (Job's) method, distribution method, solubility method, pH titration method, and spectroscopy. The continuous variation method analyzes changes in physical properties like dielectric constant when complexes form to determine stoichiometric ratios. The distribution method examines how the distribution of a solute between immiscible liquids changes with complexation to estimate stability constants. The solubility method observes whether solubility increases or decreases with the addition of a complexing agent. pH titration is reliable for complexes that affect pH upon formation. Spectroscopy techniques like UV and NMR are also used to determine rate constants and equilibrium constants.
Dr. Manjoor Ahamad Syed is an Assistant Professor in the Department of Medicinal Chemistry at Mettu University in Ethiopia. QSAR attempts to identify physicochemical properties of drugs that affect biological activity using a mathematical equation. Key physicochemical properties include hydrophobicity, electronic effects, and steric effects. QSAR involves synthesizing compounds to vary a property, plotting biological activity vs the property, and using linear regression to determine the best correlation line. The approach has been used to design many successful drug classes.
stereochemistry and drug action ; basic introduction about stereochemistry and stereoisomers ; pharmacokinetic and pharmacodynamics concept of stereochemistry ; easson Stedman hypothesis ; stereo selectivity criteria .
There are 6 main methods to analyze β-cyclodextrin complexes: 1) continuous variation method, 2) spectroscopy methods, 3) distribution methods, 4) pH titration methods, 5) solubility methods, and 6) general methods such as NMR spectroscopy and infrared spectroscopy. The document then provides details on the continuous variation, spectroscopy, pH titration, solubility, and distribution methods. It explains how each method can be used to determine stability constants and analyze complex formation between β-cyclodextrin and other molecules.
This document provides an overview of molecular variation in homologous series and isosteric replacements for medicinal chemistry. It discusses different types of molecular variations such as variations based on homologous series with different biological response curves. It also discusses isosteric replacements, including the history and development of isosterism concepts. Current isosteric and bioisosteric modifications are presented. The document also discusses molecular variations based on ring transformations, homodimer and heterodimer ligands using the twin drug approach, and molecular variations in medicinal chemistry applications.
This document summarizes a study that used group contribution methods to predict the solubility of volatile organic compounds (VOCs) in biodiesel. The study used three versions of the Universal Functional Activity Coefficient (UNIFAC) model to predict infinite dilution activity coefficients for VOCs in fatty acid methyl ester solvents that make up biodiesel. The results showed that activity coefficients decreased with increasing molecular weight for alkanes, amines, alkenes, organic acids, and alcohols. Shorter esters with lower carbon counts had higher activity coefficients than longer esters with higher carbon counts. Solubility of VOCs in biodiesel also decreased with increasing ester hydrocarbon unsaturation.
This document discusses various applications of quantitative structure-activity relationships (QSAR) in drug research and development. It describes how QSAR can provide information on receptor sites from enzyme inhibition studies, help understand the importance of physicochemical properties like log P values, and enable the use of bioisosterism to modify compounds. QSAR has correctly predicted drug activity and toxicity and is useful in drug design before compounds are synthesized.
Complexation and Protein Binding [Part-2](Method of analysis, Complexation a...Ms. Pooja Bhandare
This document discusses various methods for analyzing complexes, including continuous variation (Job's) method, distribution method, solubility method, pH titration method, and spectroscopy. The continuous variation method analyzes changes in physical properties like dielectric constant when complexes form to determine stoichiometric ratios. The distribution method examines how the distribution of a solute between immiscible liquids changes with complexation to estimate stability constants. The solubility method observes whether solubility increases or decreases with the addition of a complexing agent. pH titration is reliable for complexes that affect pH upon formation. Spectroscopy techniques like UV and NMR are also used to determine rate constants and equilibrium constants.
Dr. Manjoor Ahamad Syed is an Assistant Professor in the Department of Medicinal Chemistry at Mettu University in Ethiopia. QSAR attempts to identify physicochemical properties of drugs that affect biological activity using a mathematical equation. Key physicochemical properties include hydrophobicity, electronic effects, and steric effects. QSAR involves synthesizing compounds to vary a property, plotting biological activity vs the property, and using linear regression to determine the best correlation line. The approach has been used to design many successful drug classes.
stereochemistry and drug action ; basic introduction about stereochemistry and stereoisomers ; pharmacokinetic and pharmacodynamics concept of stereochemistry ; easson Stedman hypothesis ; stereo selectivity criteria .
There are 6 main methods to analyze β-cyclodextrin complexes: 1) continuous variation method, 2) spectroscopy methods, 3) distribution methods, 4) pH titration methods, 5) solubility methods, and 6) general methods such as NMR spectroscopy and infrared spectroscopy. The document then provides details on the continuous variation, spectroscopy, pH titration, solubility, and distribution methods. It explains how each method can be used to determine stability constants and analyze complex formation between β-cyclodextrin and other molecules.
This document provides an overview of molecular variation in homologous series and isosteric replacements for medicinal chemistry. It discusses different types of molecular variations such as variations based on homologous series with different biological response curves. It also discusses isosteric replacements, including the history and development of isosterism concepts. Current isosteric and bioisosteric modifications are presented. The document also discusses molecular variations based on ring transformations, homodimer and heterodimer ligands using the twin drug approach, and molecular variations in medicinal chemistry applications.
This document discusses complexation and protein binding. It defines complex compounds as molecules where some bonds cannot be described by classical valence theory. Complexation is the association of two molecules to form a non-covalently bonded entity with a stoichiometry. Ligands interact with central metal ions or atoms via coordinate bonds to form metal complexes. Protein binding is the formation of drug-protein complexes. Factors affecting protein binding include the drug's physicochemical properties, protein concentration and binding sites, drug interactions, and patient characteristics like age and disease state. Kinetics of protein binding influence drug absorption, distribution, metabolism, and elimination.
General principles of structure activity relationship (sar)MANISH mohan
The document discusses the general principles of Structure-Activity Relationship (SAR). SAR studies how minor modifications to a drug molecule's chemical structure can lead to major changes in its pharmacological properties. SAR is used to determine a drug's pharmacophore, reduce unwanted side effects, and develop new drugs with increased activity. The key aspects of SAR covered are the size and shape of a molecule's carbon skeleton, its stereochemistry, and the nature and degree of substitution.
Synthesis and characterization of new benzotriazole derivatives for possible ...SriramNagarajan18
This document describes the synthesis and characterization of new benzotriazole derivatives (Va-Vg) for potential central nervous system (CNS) activity. The derivatives were synthesized in multiple steps starting from O-phenylenediamene. The intermediates and final compounds were characterized using techniques like IR, 1H NMR, mass spectrometry and elemental analysis. All compounds were screened for CNS activity through gross behavioral studies and locomotor activity tests. Compound Vb containing a 4-chloro substitution showed the most promising depressant activity among the test compounds, followed by Vg and Ve.
This document discusses key concepts in medicinal chemistry including receptor interactions, drug potency and efficacy, and the stereochemical effects of drug enantiomers. Specifically, it defines receptor down-regulation as a decrease in receptor numbers induced by an agonist, and receptor up-regulation as the opposite, an agonist-induced increase in receptor numbers. It also explains that drug potency depends on both affinity, the ability of a drug to bind a receptor, and efficacy, the intensity of response produced by an agonist occupying receptors. Finally, it notes some stereoselective differences in the absorption, distribution, metabolism and excretion of drug enantiomers.
Stereochemistry refers to the three-dimensional orientation of atoms in space. The physiological properties of a drug are greatly influenced by its stereochemistry. Even optical isomers of a drug, which have the same molecular formula and connectivity but differ in their three-dimensional atomic arrangements, can have different physiological effects. There are two main types of isomerism: optical isomerism, which involves chiral centers, and geometrical isomerism, which involves differences in spatial arrangements around a double bond. The separation of isomers in a mixture is technically difficult but important as isomers can have different biological activities.
This document discusses the physicochemical property of partition coefficient for drugs. It explains that partition coefficient (P) is a ratio of the concentrations of a drug in the organic and aqueous phases of a mixture of two immiscible solvents. It then discusses how P can be used to predict drug absorption, distribution, and elimination in the body. It also explains that P values may depend on pH and drug ionization, and outlines calculations to determine true P versus apparent P. The document concludes by discussing structure-activity relationships (SARs) and quantitative structure-activity relationships (QSARs) in drug design and development.
The screening of chemical libraries with traditional methods, such as high-throughput screening (HTS), is expensive and time consuming. Quantitative structure–activity relation (QSAR) modeling is an alternative method that can assist in the selection of lead molecules by using the information from
reference active and inactive compounds. This approach requires good molecular descriptors that are representative of the molecular features responsible for the relevant molecular activity.
This document discusses structure-activity relationships (SAR) through examples of different drug molecules. It provides details on the chemical structures of camptothecin (CPT), taxol, and the flavonoid quercetin and how specific structural features relate to their biological activities. For CPT, rings A-D and the stereochemistry at C-20 are essential for anti-tumor activity, while modifications to rings C and D eliminate activity. The ester linkage and phenylisoserine chain of taxol are required for its anticancer effects. For flavonoids like quercetin, features important for radical scavenging include a catechol structure in ring B and hydroxyl groups that enable hydrogen bonding and electron de
The document discusses the structure-activity relationship (SAR) of opioids. It begins by defining SAR as the relationship between a molecule's chemical structure and its biological activity. Modifications to a drug's structure, including altering functional groups, can change its potency and effects. The structures of morphine, codeine, and heroin are examined as examples. While the methyl group on codeine decreases potency versus morphine, the acetyl groups on heroin allow it to cross the blood-brain barrier more easily and produce a stronger euphoric effect. Understanding SAR enables the design of new opioid drugs with tailored pharmacological properties.
This review summarizes potential interactions and incompatibilities between commonly used pharmaceutical excipients and active pharmaceutical ingredients in solid dosage forms. It discusses examples of interactions such as transacylation, the Maillard browning reaction, acid-base reactions, and physical changes for a variety of drug classes. The review also describes methods used to study drug-excipient compatibility, including computational prediction, binary mixture testing, differential scanning calorimetry, isothermal stress testing, and analytical techniques. Understanding interactions is important for avoiding reactivity and improving drug stability and product performance.
Stereochemistry in drug design discusses the importance of stereochemistry in drug development. It covers different types of stereoisomers like enantiomers and diastereoisomers and geometric isomers. It also discusses the thalidomide disaster and Easson-Stedman hypothesis that differences in biological activity between enantiomers result from selective reactivity of one enantiomer with receptors requiring a three-point fit. Finally, it provides examples of drugs with multiple chiral centers, geometric isomerism, conformational isomers, and acetylcholine.
Stereochemistry is the study of the three-dimensional structure of molecules. Stereoisomers are molecules that have the same bonding but different three-dimensional structures. Geometric isomers differ in the orientation of substituents around a double bond. Enantiomers are non-superimposable mirror images. Many drugs have stereoisomers that can differ significantly in their pharmacokinetic and pharmacodynamic properties, such as absorption, volume of distribution, metabolism, efficacy, and interactions. Understanding stereochemistry is important for developing safe and effective chiral drugs.
This document discusses the challenges of regulating and understanding the effects of combined exposure to toxic substances. It notes that workers are often exposed to multiple chemicals simultaneously or sequentially, but regulations typically focus on individual substances. Toxicologists classify interaction between substances as independent, dose addition, or interaction (synergism, antagonism, etc.). Understanding combined exposure effects is difficult but important, as the actual risk may be greater than predicted by dose addition. More data is needed on real-world exposure scenarios and combined toxicity to improve regulatory approaches.
Complexation and Protein Binding [Part-1](Introduction and Classification an...Ms. Pooja Bhandare
Complexation: Classification of complexation:
Metal ion or co-ordination complexes :
Inorganic type Organic molecular complexes :
Quinhydrone type
Picric acid type
Caffeine and other drug complexes
Polymer type
Inclusion or occlusion compound
Channel lattice type
Layer type
Monomolecular type
Macromolecular type
Chelates
Olefin type
Aromatic type
Pi (п) complexes
Sigma (б) complexes
Sandwich complexes
Molecular modeling simulation study of interactions inAlexander Decker
The document discusses a molecular modeling simulation study of the interactions between starch and poly(acrylic acid) (PAA). Calculations using semi-empirical AM1 and PM3 methods were performed on complexes of glucose (from starch) and acrylic acid monomers (from PAA) with 1-3 monomers. The results show that hydrogen bonding occurs between the hydroxyl groups of glucose and the carbonyl groups of acrylic acid. Binding energies were negative, indicating stable interactions. Vibrational frequency analysis showed shifts in carbonyl and hydroxyl stretching frequencies upon complex formation, further suggesting hydrogen bond formation between the two polymers. The study provides evidence that hydrogen bonding promotes compatibility between starch and PAA.
The document discusses 2D-QSAR (Quantitative Structure-Activity Relationship) analysis methods. It defines QSAR as mathematical relationships linking chemical structure and pharmacological activity. It describes several common 2D-QSAR methods including Hansch analysis, Free Wilson analysis, and various statistical methods. Cluster analysis is discussed as a way to group similar molecules and select a diverse subset for analysis. Molecular descriptors that encode structural, electronic, and topological properties are also introduced.
This document discusses stereoisomers in pharmacology. It begins with an introduction to stereochemistry and the three types of isomers - constitutional, configurational, and conformational. It then discusses the history of isomerism, chirality, enantiomers, and nomenclature systems. The document outlines important differences between single enantiomers and racemic mixtures in terms of pharmacokinetic and pharmacodynamic properties. It provides several examples to illustrate these differences. Finally, the document concludes that increasing availability of single-enantiomer drugs can provide safer, better tolerated, and more efficacious treatments compared to racemic mixtures.
The film poster depicts the main protagonist with makeup suggesting elegance relating to the film's focus on ballet. However, her face has a crack, implying an underlying psychological element or hidden imperfections. As a "Black Swan", she contrasts with the typical "White Swan" and suggests a darker side to her perfect public image. The large black title and genre imply an element of mystery or darkness surrounding the main character.
OLED (Organic Light Emitting Diode) is a light emitting diode that uses organic compounds that emit light when electric current is applied. It consists of a series of thin organic films placed between two conductors. OLEDs are very thin, only 100-500 nanometers, and emit light through electroluminescence when electric current passes through the organic layers. They can be passive matrix or active matrix and come in transparent, top-emitting, and flexible varieties. OLEDs are being used in applications like TVs, phones, keyboards, and lighting due to advantages like being thinner, lighter, more power efficient, and flexible compared to LCDs.
The document discusses security systems from Eagle-High including a gas chromatograph explosive detection system that is portable, sensitive, and accurate at detecting both commercial and improvised explosives. It also mentions an under vehicle inspection system that can be portable or fixed, and automatically scans vehicle chassis to detect objects like explosives, drugs, merchandise, or people hidden underneath. The systems are described as portable, easy to install and use with only brief training required, not needing export licenses, and providing fast, accurate and cost-effective security screening.
This document discusses complexation and protein binding. It defines complex compounds as molecules where some bonds cannot be described by classical valence theory. Complexation is the association of two molecules to form a non-covalently bonded entity with a stoichiometry. Ligands interact with central metal ions or atoms via coordinate bonds to form metal complexes. Protein binding is the formation of drug-protein complexes. Factors affecting protein binding include the drug's physicochemical properties, protein concentration and binding sites, drug interactions, and patient characteristics like age and disease state. Kinetics of protein binding influence drug absorption, distribution, metabolism, and elimination.
General principles of structure activity relationship (sar)MANISH mohan
The document discusses the general principles of Structure-Activity Relationship (SAR). SAR studies how minor modifications to a drug molecule's chemical structure can lead to major changes in its pharmacological properties. SAR is used to determine a drug's pharmacophore, reduce unwanted side effects, and develop new drugs with increased activity. The key aspects of SAR covered are the size and shape of a molecule's carbon skeleton, its stereochemistry, and the nature and degree of substitution.
Synthesis and characterization of new benzotriazole derivatives for possible ...SriramNagarajan18
This document describes the synthesis and characterization of new benzotriazole derivatives (Va-Vg) for potential central nervous system (CNS) activity. The derivatives were synthesized in multiple steps starting from O-phenylenediamene. The intermediates and final compounds were characterized using techniques like IR, 1H NMR, mass spectrometry and elemental analysis. All compounds were screened for CNS activity through gross behavioral studies and locomotor activity tests. Compound Vb containing a 4-chloro substitution showed the most promising depressant activity among the test compounds, followed by Vg and Ve.
This document discusses key concepts in medicinal chemistry including receptor interactions, drug potency and efficacy, and the stereochemical effects of drug enantiomers. Specifically, it defines receptor down-regulation as a decrease in receptor numbers induced by an agonist, and receptor up-regulation as the opposite, an agonist-induced increase in receptor numbers. It also explains that drug potency depends on both affinity, the ability of a drug to bind a receptor, and efficacy, the intensity of response produced by an agonist occupying receptors. Finally, it notes some stereoselective differences in the absorption, distribution, metabolism and excretion of drug enantiomers.
Stereochemistry refers to the three-dimensional orientation of atoms in space. The physiological properties of a drug are greatly influenced by its stereochemistry. Even optical isomers of a drug, which have the same molecular formula and connectivity but differ in their three-dimensional atomic arrangements, can have different physiological effects. There are two main types of isomerism: optical isomerism, which involves chiral centers, and geometrical isomerism, which involves differences in spatial arrangements around a double bond. The separation of isomers in a mixture is technically difficult but important as isomers can have different biological activities.
This document discusses the physicochemical property of partition coefficient for drugs. It explains that partition coefficient (P) is a ratio of the concentrations of a drug in the organic and aqueous phases of a mixture of two immiscible solvents. It then discusses how P can be used to predict drug absorption, distribution, and elimination in the body. It also explains that P values may depend on pH and drug ionization, and outlines calculations to determine true P versus apparent P. The document concludes by discussing structure-activity relationships (SARs) and quantitative structure-activity relationships (QSARs) in drug design and development.
The screening of chemical libraries with traditional methods, such as high-throughput screening (HTS), is expensive and time consuming. Quantitative structure–activity relation (QSAR) modeling is an alternative method that can assist in the selection of lead molecules by using the information from
reference active and inactive compounds. This approach requires good molecular descriptors that are representative of the molecular features responsible for the relevant molecular activity.
This document discusses structure-activity relationships (SAR) through examples of different drug molecules. It provides details on the chemical structures of camptothecin (CPT), taxol, and the flavonoid quercetin and how specific structural features relate to their biological activities. For CPT, rings A-D and the stereochemistry at C-20 are essential for anti-tumor activity, while modifications to rings C and D eliminate activity. The ester linkage and phenylisoserine chain of taxol are required for its anticancer effects. For flavonoids like quercetin, features important for radical scavenging include a catechol structure in ring B and hydroxyl groups that enable hydrogen bonding and electron de
The document discusses the structure-activity relationship (SAR) of opioids. It begins by defining SAR as the relationship between a molecule's chemical structure and its biological activity. Modifications to a drug's structure, including altering functional groups, can change its potency and effects. The structures of morphine, codeine, and heroin are examined as examples. While the methyl group on codeine decreases potency versus morphine, the acetyl groups on heroin allow it to cross the blood-brain barrier more easily and produce a stronger euphoric effect. Understanding SAR enables the design of new opioid drugs with tailored pharmacological properties.
This review summarizes potential interactions and incompatibilities between commonly used pharmaceutical excipients and active pharmaceutical ingredients in solid dosage forms. It discusses examples of interactions such as transacylation, the Maillard browning reaction, acid-base reactions, and physical changes for a variety of drug classes. The review also describes methods used to study drug-excipient compatibility, including computational prediction, binary mixture testing, differential scanning calorimetry, isothermal stress testing, and analytical techniques. Understanding interactions is important for avoiding reactivity and improving drug stability and product performance.
Stereochemistry in drug design discusses the importance of stereochemistry in drug development. It covers different types of stereoisomers like enantiomers and diastereoisomers and geometric isomers. It also discusses the thalidomide disaster and Easson-Stedman hypothesis that differences in biological activity between enantiomers result from selective reactivity of one enantiomer with receptors requiring a three-point fit. Finally, it provides examples of drugs with multiple chiral centers, geometric isomerism, conformational isomers, and acetylcholine.
Stereochemistry is the study of the three-dimensional structure of molecules. Stereoisomers are molecules that have the same bonding but different three-dimensional structures. Geometric isomers differ in the orientation of substituents around a double bond. Enantiomers are non-superimposable mirror images. Many drugs have stereoisomers that can differ significantly in their pharmacokinetic and pharmacodynamic properties, such as absorption, volume of distribution, metabolism, efficacy, and interactions. Understanding stereochemistry is important for developing safe and effective chiral drugs.
This document discusses the challenges of regulating and understanding the effects of combined exposure to toxic substances. It notes that workers are often exposed to multiple chemicals simultaneously or sequentially, but regulations typically focus on individual substances. Toxicologists classify interaction between substances as independent, dose addition, or interaction (synergism, antagonism, etc.). Understanding combined exposure effects is difficult but important, as the actual risk may be greater than predicted by dose addition. More data is needed on real-world exposure scenarios and combined toxicity to improve regulatory approaches.
Complexation and Protein Binding [Part-1](Introduction and Classification an...Ms. Pooja Bhandare
Complexation: Classification of complexation:
Metal ion or co-ordination complexes :
Inorganic type Organic molecular complexes :
Quinhydrone type
Picric acid type
Caffeine and other drug complexes
Polymer type
Inclusion or occlusion compound
Channel lattice type
Layer type
Monomolecular type
Macromolecular type
Chelates
Olefin type
Aromatic type
Pi (п) complexes
Sigma (б) complexes
Sandwich complexes
Molecular modeling simulation study of interactions inAlexander Decker
The document discusses a molecular modeling simulation study of the interactions between starch and poly(acrylic acid) (PAA). Calculations using semi-empirical AM1 and PM3 methods were performed on complexes of glucose (from starch) and acrylic acid monomers (from PAA) with 1-3 monomers. The results show that hydrogen bonding occurs between the hydroxyl groups of glucose and the carbonyl groups of acrylic acid. Binding energies were negative, indicating stable interactions. Vibrational frequency analysis showed shifts in carbonyl and hydroxyl stretching frequencies upon complex formation, further suggesting hydrogen bond formation between the two polymers. The study provides evidence that hydrogen bonding promotes compatibility between starch and PAA.
The document discusses 2D-QSAR (Quantitative Structure-Activity Relationship) analysis methods. It defines QSAR as mathematical relationships linking chemical structure and pharmacological activity. It describes several common 2D-QSAR methods including Hansch analysis, Free Wilson analysis, and various statistical methods. Cluster analysis is discussed as a way to group similar molecules and select a diverse subset for analysis. Molecular descriptors that encode structural, electronic, and topological properties are also introduced.
This document discusses stereoisomers in pharmacology. It begins with an introduction to stereochemistry and the three types of isomers - constitutional, configurational, and conformational. It then discusses the history of isomerism, chirality, enantiomers, and nomenclature systems. The document outlines important differences between single enantiomers and racemic mixtures in terms of pharmacokinetic and pharmacodynamic properties. It provides several examples to illustrate these differences. Finally, the document concludes that increasing availability of single-enantiomer drugs can provide safer, better tolerated, and more efficacious treatments compared to racemic mixtures.
The film poster depicts the main protagonist with makeup suggesting elegance relating to the film's focus on ballet. However, her face has a crack, implying an underlying psychological element or hidden imperfections. As a "Black Swan", she contrasts with the typical "White Swan" and suggests a darker side to her perfect public image. The large black title and genre imply an element of mystery or darkness surrounding the main character.
OLED (Organic Light Emitting Diode) is a light emitting diode that uses organic compounds that emit light when electric current is applied. It consists of a series of thin organic films placed between two conductors. OLEDs are very thin, only 100-500 nanometers, and emit light through electroluminescence when electric current passes through the organic layers. They can be passive matrix or active matrix and come in transparent, top-emitting, and flexible varieties. OLEDs are being used in applications like TVs, phones, keyboards, and lighting due to advantages like being thinner, lighter, more power efficient, and flexible compared to LCDs.
The document discusses security systems from Eagle-High including a gas chromatograph explosive detection system that is portable, sensitive, and accurate at detecting both commercial and improvised explosives. It also mentions an under vehicle inspection system that can be portable or fixed, and automatically scans vehicle chassis to detect objects like explosives, drugs, merchandise, or people hidden underneath. The systems are described as portable, easy to install and use with only brief training required, not needing export licenses, and providing fast, accurate and cost-effective security screening.
The document provides a performance evaluation for Carlos Joseph T. Juan, who works as an Office Clerk for Palawan Electric Cooperative. Over the evaluation period, Mr. Juan received high ratings between 95-100 for job performance criteria like verifying membership details, linking accounts, and assisting customers. He also scored between 96-99 for core competencies such as job knowledge, teamwork, responsibility, and customer service orientation. Based on these results, his overall performance rating was 97.9 out of 100. The evaluation recommends his contract be renewed.
The document reviews equations of state and their applicability, focusing on phase equilibrium modeling. It discusses several common equations of state (van der Waals, Redlich-Kwong, Soave-Redlich-Kwong, Peng-Robinson), outlining their development, strengths/weaknesses, and applicability. The key intention is to use the Peng-Robinson equation of state to compute thermodynamic interactions of volatile organic compounds in biodiesel polymers to aid in separation processes by simulating phase equilibria without costly actual measurements.
Application of COSMO-RS-DARE as a Tool for Testing Consistency of Solubility ...Maciej Przybyłek
This study examined the solubility of coumarin, a naturally occurring compound, in various alcohols using experimental and computational methods. Inconsistencies were found in literature solubility data for coumarin. The study developed a theoretical approach using COSMO-RS-DARE modeling to test solubility data consistency and identify outliers. Experimentally measured solubility data for coumarin in a series of alcohols matched the back-calculated COSMO-RS-DARE values, validating the theoretical approach. Linear regressions were also developed to correlate COSMO-RS-DARE integration parameters with molecular descriptors.
Estimating the Biodegradation Kinetics by Mixed Culture Degrading Pyrene (Pyr)AZOJETE UNIMAID
This document discusses the biodegradation kinetics of pyrene (Pyr) degradation by a mixed culture. Experiments were conducted to determine the optimal temperature, pH, and Pyr concentrations for degradation. Kinetics experiments were then carried out at 30°C and pH 7 using initial Pyr concentrations ranging from 10-700 ppm. The results showed Pyr concentrations between 100-700 ppm inhibited the mixed culture. Concentrations between 10-100 ppm did not inhibit growth. A first-order rate constant model best described the degradation kinetics, with the highest rate (0.0487 mg/Lh) at 20 ppm Pyr. On average, the mixed culture could degrade over 0.0696 p
New Screening Protocol for Effective Green Solvents Selection of Benzamide, S...Maciej Przybyłek
New protocol for screening efficient and environmentally friendly solvents was proposed and experimentally verified. The guidance for solvent selection comes from computed solubility via COSMO-RS approach. Furthermore, solute-solvent affinities computed using advanced quantum chemistry level were used as a rationale for observed solvents ranking. The screening protocol pointed out that 4-formylomorpholine (4FM) is an attractive solubilizer compared to commonly used aprotic solvents such as DMSO and DMF. This was tested experimentally by measuring the solubility of the title compounds in aqueous binary mixtures in the temperature range between 298.15 K and 313.15 K. Additional measurements were also performed for aqueous binary mixtures of DMSO and DMF. It has been found that the solubility of studied aromatic amides is very high and quite similar in all three aprotic solvents. For most aqueous binary mixtures, a significant decrease in solubility with a decrease in the organic fraction is observed, indicating that all systems can be regarded as efficient solvent-anti-solvent pairs. In the case of salicylamide dissolved in aqueous-4FM binary mixtures, a strong synergistic effect has been found leading to the highest solubility for 0.6 mole fraction of 4-FM.
JBEI Research Highlights Slides - July 2022SaraHarmon4
Anaerobic fungi produce a wealth of enzymes that can act on cellulose, hemicellulose, and lignin. These enzymes show promise for accelerating the breakdown of lignocellulose for industrial applications like chemical and fuel production. Molecular dynamics simulations provide insights into how these enzymes may interact with lignocellulose and enable its breakdown. This could allow enzymes from anaerobic fungi to be applied industrially.
Intermolecular Interactions of Edaravone in Aqueous Solutions of Ethaline and...Maciej Przybyłek
Edaravone, acting as a cerebral protective agent, is administered to treat acute brain infarction. Its poor solubility is addressed here by means of optimizing the composition of the aqueous choline chloride (ChCl)-based eutectic solvents prepared with ethylene glycol (EG) or glycerol (GL) in the three different designed solvents compositions. The slurry method was used for spectroscopic solubility determination in temperatures between 298.15 K and 313.15 K. Measurements confirmed that ethaline (ETA = ChCl:EG = 1:2) and glyceline (GLE = ChCl:GL = 1:2) are very effective solvents for edaravone. The solubility at 298.15 K in the optimal compositions was found to be equal xE = 0.158 (cE = 302.96 mg/mL) and xE = 0.105 (cE = 191.06 mg/mL) for glyceline and ethaline, respectively. In addition, it was documented that wetting of neat eutectic mixtures increases edaravone solubility which is a fortunate circumstance not only from the perspective of a solubility advantage but also addresses high hygroscopicity of eutectic mixtures. The aqueous mixture with 0.6 mole fraction of the optimal composition yielded solubility values at 298.15 K equal to xE = 0.193 (cE = 459.69 mg/mL) and xE = 0.145 (cE = 344.22 mg/mL) for glyceline and ethaline, respectively. Since GLE is a pharmaceutically acceptable solvent, it is possible to consider this as a potential new liquid form of this drug with a tunable dosage. In fact, the recommended amount of edaravone administered to patients can be easily achieved using the studied systems. The observed high solubility is interpreted in terms of intermolecular interactions computed using the Conductor-like Screening Model for Real Solvents (COSMO-RS) approach and corrected for accounting of electron correlation, zero-point vibrational energy and basis set superposition errors. Extensive conformational search allowed for identifying the most probable contacts, the thermodynamic and geometric features of which were collected and discussed. It was documented that edaravone can form stable dimers stabilized via stacking interactions between five-membered heterocyclic rings. In addition, edaravone can act as a hydrogen bond acceptor with all components of the studied systems with the highest affinities to ion pairs of ETA and GLE. Finally, the linear regression model was formulated, which can accurately estimate edaravone solubility utilizing molecular descriptors obtained from COSMO-RS computations. This enables the screening of new eutectic solvents for finding greener replacers of designed solvents. The theoretical analysis of tautomeric equilibria confirmed that keto-isomer edaravone is predominant in the bulk liquid phase of all considered deep eutectic solvents (DES).
Phase equilibrium feasibility studies of free fatty acids extraction from pal...Alexander Decker
This document summarizes a study that investigated the extraction of free fatty acids from palm oil using supercritical carbon dioxide. The study assessed the feasibility of using a thermodynamic model based on UNIFAC to predict phase equilibrium and activity coefficients for the carbon dioxide/fatty acid system. Experimental results were obtained for extract mole fraction at different pressures from 60-180 bars and temperatures of 313.15K and 353.15K. Mass transfer parameters like diffusion coefficient and solubility were also determined. The model predictions matched reasonably well with experimental data.
The document discusses retrosynthetic analysis, a technique developed by Elias Corey for planning organic syntheses. It involves deconstructing a target molecule into simpler precursor structures by applying the reverse of known reactions. Each precursor is then further deconstructed until commercially available starting materials are reached, mapping out possible synthesis routes. This allows for more systematic planning than trial-and-error methods. Retrosynthesis generates a "tree" of intermediates and pathways that is then pruned according to availability and strategy to give practical synthesis routes. It can reveal multiple starting materials or convergent syntheses for more efficient production.
1 s2.0-s037838121100207 x-main.correlation of thermodynamic modeling and mole...Josemar Pereira da Silva
The document describes a method for correlating thermodynamic modeling and molecular simulations to predict liquid-liquid equilibrium in ternary polymer mixtures. The method uses a modified double lattice theory thermodynamic model combined with molecular simulations to determine interaction energy parameters. Dummy atoms are used to represent polymer segments in the simulations. The method is applied to four real ternary polymer systems, with the energy parameters directly used in the thermodynamic model. The results show good agreement with experimental observations using one or no adjustable parameters.
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The document describes a method for correlating thermodynamic modeling and molecular simulations to predict liquid-liquid equilibrium in ternary polymer mixtures. The method uses a modified double lattice theory thermodynamic model combined with molecular simulations to determine interaction energy parameters. Dummy atoms are used to represent polymer segments in the simulations. The method is applied to four real ternary polymer systems, with the energy parameters directly used in the thermodynamic model. The results show good agreement with experimental observations using one or no adjustable parameters.
Solubility Characteristics of Acetaminophen and Phenacetin in Binary Mixtures...Maciej Przybyłek
The solubility of active pharmaceutical ingredients is a mandatory physicochemical characteristic in pharmaceutical practice. However, the number of potential solvents and their mixtures prevents direct measurements of all possible combinations for finding environmentally friendly, operational and cost-effective solubilizers. That is why support from theoretical screening seems to be valuable. Here, a collection of acetaminophen and phenacetin solubility data in neat and binary solvent mixtures was used for the development of a nonlinear deep machine learning model using new intuitive molecular descriptors derived from COSMO-RS computations. The literature dataset was augmented with results of new measurements in aqueous binary mixtures of 4-formylmorpholine, DMSO and DMF. The solubility values back-computed with the developed ensemble of neural networks are in perfect agreement with the experimental data, which enables the extensive screening of many combinations of solvents not studied experimentally within the applicability domain of the trained model. The final predictions were presented not only in the form of the set of optimal hyperparameters but also in a more intuitive way by the set of parameters of the Jouyban–Acree equation often used in the co-solvency domain. This new and effective approach is easily extendible to other systems, enabling the fast and reliable selection of candidates for new solvents and directing the experimental solubility screening of active pharmaceutical ingredients.
The document discusses retrosynthetic analysis, a technique used in organic synthesis planning. It involves deconstructing a target molecule into simpler precursor structures by applying the reverse of known reactions. This is done iteratively until commercially available starting materials are reached. Key points discussed include:
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This document presents a worksheet-based adsorption model that considers both charged and neutral adsorption sites. The model combines a Gouy-Chapman-Stern model for adsorption to charged sites with a Langmuir equation and partition mechanism for adsorption to neutral sites. The model allows for multiple types of charged and neutral sites. Experimental adsorption data for metoclopramide, tetracycline, and chlorpheniramine were well fit by the model using a single set of adjustable parameters for each compound. The versatility and accessibility of the worksheet-based model makes it a potentially useful tool for evaluating the fate of pollutants in the environment.
Michaelis-Menten Kinetics in Transient State: Proposal for Reversible Inhibit...IJERA Editor
The enzymatic processes according Michaelis-Menten kinetics have been studied from various approaches to
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presents by graphs showing the variation of the enzyme and enzyme complexes, also the variation of substrate
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seen in the Michaelis-Menten kinetics, where complex of reaction is rapidly formed and throughout the process,
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The effect of temperature onthe micellization of an anionic surfactant in mix...iosrjce
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This document describes the synthesis and characterization of a new cationic surfactant derived from 5-Chloro-1H-indole-2,3-dione. The surfactant was synthesized in two steps: first, 5-Chloroisatin was alkylated with 1,6-dibromohexane under phase transfer catalysis conditions. Second, the product was quaternized with trimethylamine in acetone solution. The structures were confirmed using NMR spectroscopy. The critical micelle concentration of the surfactant in water was determined to be 5.10-3 M using conductivity measurements at room temperature. In conclusion, a new cationic surfactant was successfully synthesized and its micell
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This thesis examines the use of quantum mechanical modeling to understand organic compound sorption reactions with iron oxides. The student used computational modeling software to calculate the relative Gibbs free energy of selected organic acids sorbing to iron oxides. Theoretical spectra generated from the modeling were evaluated against previous experimental IR spectra to validate the modeling approach. Overall, the research aims to demonstrate that advanced quantum mechanical modeling is an effective technique for predicting sorption mechanisms and understanding organic contaminant behavior in the environment.
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This document provides an overview of experimental excess enthalpies of binary mixtures containing ionic liquids and molecular solvents. It also evaluates the ability of the COSMO-RS (conductor-like screening model for real systems) method to predict these excess enthalpies. The document finds that COSMO-RS generally agrees well with experimental data and can depict the molecular interactions governing the excess enthalpies. COSMO-RS is thus useful for selecting ionic liquid candidates for applications based on thermophysical property predictions prior to extensive experimental measurements.
Overview of the excess enthalpies of the binary mixtures composed
Sashay Paper 2- Final V003
1.
Abstract— This work investigated the suitability of biodiesel
(predominantly Methyl Linolenate, Methyl Palmitate, Methyl
Oleate and Methyl Stearate) as an absorbent for the recovery
of VOCs from waste gas process streams through absorption.
The objective was to predict the vapour liquid equilibria
(VLE) data in the form of infinite dilution activity coefficients
for five VOC families, in fatty acid methyl ester solvents at
varying temperature. The Original Universal Functional Group
Activity Coefficient (UNIFAC) model (Fredenslund et al.,
1975) [1], Modified UNIFAC (Larsen et al., 1981) [2] and
Modified UNIFAC (Bastos et al., 1988) [3] was used to
predict the required phase equilibrium Alkanes, alcohols and
acids/ester interactions showed an increase in activity
coefficients with increase in temperature. The influence of
temperature on the activity coefficients for alkene and amine
families was negligible. The solubility of VOCs in biodiesel
decreases with increase in ester hydrocarbon unsaturation.
The solubility of VOCs increased with increase in ester
molecular weight.
Keywords— Activity coefficients, biodiesel, phase equilibrium,
Universal Functional Activity Coefficient.
I. INTRODUCTION
The National Environmental Management: Air Quality Act 39
of 2004, has forced all industries to closely monitor any
effluents emitted to the environment. Thermodynamic models
which are required to predict phase equilibrium data are
applied in these situations, as their function is to compute
vapour liquid equilibria. It is crucial to use models in the
determination of these equilibria since actual measurements
S.Ramdharee is with the Department of Chemical Engineering, Faculty of
Engineering and the Built Environment, University of Johannesburg,
Auckland Park, Johannesburg 2028 (e-mail: sashayr007@gmail.com;
sramdharee@csir.co.za)
M.Belaid is with the Department of Chemical Engineering, Faculty of
Engineering and the Built Environment, University of Johannesburg,
Doornfontein, Johannesburg 2028;(e-mail: mbelaid@uj.ac.za )
E. Muzenda is with the Department of Chemical Engineering, Faculty of
Engineering and the Built Environment, University of Johannesburg,
Doornfontein, Johannesburg 2028; phone: 0027-11-5596817; fax: 0027-11-
5596430; e-mail: emuzenda@uj.ac.za )
are costly and time-consuming. The use of group contribution
methods to predict VLE data will provide information which
could be used as a design basis for absorption processes to
eliminate or control the release of VOCs into the atmosphere.
A. Absorption
Absorption is a separation method which involves the removal
of a compound from a gas stream by contacting the
contaminated air with a suitable absorption fluid. The two
common absorption systems are; systems where interface
transfer is purely by physical processes and those where a
chemical reaction occurs between the component being
absorbed and the absorbent.
Absorption is a physical process, and it follows the Nerst
partition law which states that the ratio of concentrations of
some solute species in two bulk phases in contact is constant
for a given solute and bulk phase.
)12,(
2
1
xNK
x
x
constant (1)
In equation 1, the partition coefficient KN depends on the
temperature. This equation is valid if the concentrations are
low and if the species x does not change its form in any of the
two phases. If such a molecule undergoes association or
dissociation then this equation still describes the equilibrium
of x in both phases, but only for the same form [4].
B. Biodiesel Solvent
Biodiesel is environmentally friendly, has a low volatility and
is also a renewable material with low viscosity and good
solubility properties [5]. The largest fraction of biodiesel
consists of C16-C18 methyl esters which are readily
biodegradable due to their chemical nature and can be
domestically produced and obtained at competitive prices [6].
Biodiesel is produced from vegetable oils by converting the
triglyceride oils to methyl (or ethyl) esters through a process
known as transesterification. The transesterification process
reacts alcohol with the oil to release three "ester chains" from
the glycerin backbone of each triglyceride. Duffy and Patrick,
Volatile Organic Compounds- Biodiesel
Thermodynamic Interactions: Influence of
Temperature
Sashay Ramdharee, Mohamed Belaid and Edison Muzenda
2. 1883 [7] were responsible for the transesterification of
vegetable oil.
The selection of a suitable scrubbing solvent for a specific
waste gas stream composition is influenced by a high
absorption capacity for the separating component, a high
selectivity with reference to other gases, low toxicity and low
volatility.
J Hu, Z Du, Z Tang and E Min, 2004 [8] investigated the
suitability of biodiesel as a solvent. They confirmed that the
small quantities of non-monoalkyl esters (eg. glycerides) in
biodiesel have effects on the solvent power of biodiesel. The
length of the carbon chain of the fatty acid group of biodiesel
has an effect on the solvent power of biodiesel, and the longer
the carbon chain, the weaker the solvent power. The
unsaturated fatty acid esters have a higher solvent dissolving
power than the saturated fatty esters, but the number of double
bonds in the unsaturated fatty acid esters has little effect on the
solvent power.
C. Model Selection
Infinite dilution activity coefficients play an important role in
the analysis and design of separation processes. At infinite
dilution the single solute molecule is completely surrounded
by the solvent. Hence, infinite dilution activity coefficients,
(γ∞
) are useful as they give a measure of the greatest degree of
non-ideality of a mixture [9].
The most successful methods currently used for the calculation
of activity coefficients are the group contribution methods, in
which the liquid phase is considered to be a mixture of
structural groups. The most well-known and accurate of the
group contribution methods proposed is the Universal
Functional Activity Coefficient (UNIFAC) [10].
The UNIFAC model was first published in 1975 by
Fredenslund, Jones and Prausnitz of the University of
California [11]. The UNIFAC method is a semi-empirical
system for the prediction of non-electrolyte activity estimation
in non-ideal mixtures and it makes use of the functional groups
present in the molecules that make up the liquid mixture to
compute activity coefficients. By utilising interactions for each
of the functional groups present in the molecules, as well as
some binary interaction coefficients, the activity of each of the
solutions can be calculated [12]. In the Original UNIFAC
model (Fredenslund); the activity coefficient is expressed as
the sum of the combinatorial and residual parts respectively
[13].
r
i
c
ii lnlnln
(2)
In equation (2), γcom
and γres
represent the combinatorial and
the residual components respectively. Many modifications
have been proposed to the both the residual and combinatorial
terms in order to improve the performance of the UNIFAC
model in the prediction of VLE, γ∞
and excess enthalpies.
II. GROUP CONTRIBUTION METHODS
The group contribution method uses the principle that the
structures of chemical components are always the same in
many different molecules. This coupled with a single, double
or triple bonds reinforces that there are only ten atom types
and three bond types with which we can build thousands of
components. The next more complex building blocks of the
components are the functional groups which are themselves
built of a few atoms and bonds.
Group contribution methods are used to predict the properties
of pure components and mixtures by using group properties.
This reduces the amount of data required. Therefore, instead
of requiring the properties of millions of components, only the
data for a few groups are required.
The group contribution concept has been used to estimate
various chemical properties of pure compounds such as
densities, heat capacities and critical constants [14]. Since the
early applications of group contribution methods, they have
been developed and applied to calculate activity coefficients of
the components in a liquid mixture. When considering
mixtures of molecules in terms of the fundamental groupings
of atoms, it should be made clear that the following aspects
need to be accounted for; the organization of the molecules
in the solution and in the standard state, the restrictions
imposed on these interactions by the organization of the
groups into molecules and the interaction of various groups
which can occur in the solution and in the standard state.
The advantage of GCMs is that it allows for systematic
interpolation and extrapolation of VLE data for many chemical
mixtures. It also offers an appropriate way of predicting
properties of mixtures for which experimental data is
insufficient. When considering such mixtures it is not
necessary to measure the intermolecular interaction because
they can be calculated whenever the appropriate group
interaction parameters are known [15]. However, these are
found from experimental data not necessarily with the same
molecules as those in the investigated mixture, but containing
the same functional groups.
A. Original UNIFAC model (Fredenslund et al.,
1975)
In this model, the infinite dilution activity coefficient is
expressed as the sum of the combinatorial and residual
contributions:
r
i
c
ii lnlnln
(3)
In equation (3),
c
iln is the combinatorial part accounting for
differences in the size and shape of the molecules and
r
iln is
the residual that accounts mainly for the effects arising from
energetic interactions between groups present in solution.
For the combinatorial part:
3.
i
i
i
i
i
i
i
i
ic
i q
z
xx
1ln
2
1lnln (4)
In equation (4), i , i is the molar weighted segment and area
fractional components for the ith
molecule in the total system, z
being the coordination number respectively, which is found to
be relatively insensitive to change and is quoted as a constant
having the value of 10. ri and qi are calculated from the group
surface area and volume contributions; These parameters are
calculated as follows:
j
jj
ii
i
rx
rx
(5)
k
k
i
ki Rvr (6)
k
k
i
ki Qvq (7)
j
jj
ii
i
qx
qx
(8)
For the residual component of the activity
r
i , is due to
energetic interactions between groups present in the system.
The residual component of the activity for the ith
molecule
containing n unique functional groups can be written as
follows:
)ln(lnln i
kk
k
i
k
r
i v (9)
m
n
nmn
mkm
m
mkmkk Q
ln1ln (10)
In equation (10), k is the activity of an isolated group in a
solution consisting only of molecules of type i. The
formulation of the residual activity ensures that the condition
for the limiting case of a single molecule in a pure component
solution is abided by ensuring that the activity is equal to 1.
m is the summation of the area fraction of group m, over all
the different groups and is somewhat similar in form, but not
the same as i . mn is the group interaction parameter and is
a measure of the interaction energy between groups. Xn is the
group mole fraction, which is the number of groups.
In equation (11), m being the group parameter shown as:
n
nn
mm
m
xQ
xQ
(11)
In equation (12), mx is the group mole fraction shown as:
nj
j
i
n
j
j
i
m
m
xv
xv
x
,
(12)
In equation (13), mn the group interaction parameter is
determined by:
T
amn
mn exp (13)
Thus mna still represents the net energy of interaction
between groups m and n and has the units of SI Kelvin. These
interaction energy values are obtained from experimental data
and are usually tabulated [16].
B. Modified UNIFAC (Larsen et al., 1981)
This model is the result of two modifications that have been
done with respect to the original UNIFAC model. Larsen
presented a modified version of the UNIFAC (Lyngby
modified UNIFAC) in which the Staverman-Guggeheim
combinatorial part was changed to a Flory-Huggings
combinatorial part with a modified volume fraction. He also
introduced temperature dependant group interaction
parameters. This model allows for the simultaneous
presentation of VLE and excess enthalpies. It was also
capable of presenting liquid-liquid equilibria using the
modified UNIFAC-VLE parameters with the same quality as
the original UNIFAC with LLE based parameters, confirmed
in 1982 by Magnusses [17]. The combinatorial term and the
group interaction parameters of the residual part were
modified according to equations (14) and (15):
i
i
i
icomb
i xx
1lnln (14)
In equation (14), i the segment fraction of component (i) is
determined by:
jj
ii
i
rx
rx 3
2
(15)
And second, the interaction parameter in the residual part
T
TT
T
T
TcTTba mnmnmn
mn
)ln()(
exp
0
0
0
(16)
In equation (16), 0T is taken as a reference temperature equal
to 298.15K (25o
C)
4. C. Modified UNIFAC (Bastos et al., 1988)
The Modified UNIFAC (Bastos et al., 1988) only modifies the
combinatorial part of the Original UNIFAC from Fredenslund
et al. [18]
i
i
i
i
i
i
i
i
ic
i q
z
xx
1ln
2
1lnln (17)
In equation (17), i is determined from:
j
jj
ii
i
rx
rx
3
2
(18)
III. METHODOLOGY
In order to facilitate prompt computations, Microsoft Excel
spreadsheets were used. Minimal manual input was required
with most of the required inputs being obtained by formulae
which included lookup references. Tables which included,
Component Identification, Original UNIFAC Group
Interaction Parameters (GIP), Modified UNIFAC Group
Interaction Parameters (GIP), Van der Waals parameters, and
‘Rk’ and ‘Qk’ parameter tables, were generated in order to
facilitate the computation procedure.
The selected VOCs were added to a table where each selected
VOC was broken down into the constituent functional groups
(in terms of type and quantity) which encompassed the
compound in question. The ‘Rk’ and ‘Qk’ parameters and
Component identification table was sorted in ascending order
in terms of sub-groups to facilitate the ‘Vlookup’ function.
For the GIP tables, a cross-reference table was set up in
ascending order in terms of both parameters ‘Ψnm’ and ‘Ψmn’
numerical identities in order to facilitate the ‘Vlookup’ and
‘Hlookup’ functionality.
IV. RESULTS & DISCUSSION
This work discusses infinite dilution activity coefficients for
25 volatile organic compounds in four methyl esters namely
methyl linolenate, methyl oleate, methyl stearate and methyl
palmitate. The influence of temperature on activity
coefficients was studied at a temperature range of 298 K to
398K. Previous studies indicate that a temperature of
approximately 308K is favourable for the absorption of
organic compounds in polymeric solvents [20].
5. A. Alkanes
a) d)
b) e)
a) f)
Figure 4-1: The effect of temperature variation on the Alkane family in Methyl Palmitate for
a) Original UNIFAC b) Modified UNIFAC Bastos; c) Modified UNIFAC Larsen; Methyl
Linolenate for d) Original UNIFAC; e) Modified UNIFAC Bastos; f) Modified UNIFAC
Larsen.
0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
298.15 328.15 358.15 388.15
Activitycoefficient
Temperature(K)
0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
298.15 328.15 358.15 388.15
Activitycoefficient
Temperature(K)
0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
0.9
298.15 328.15 358.15 388.15
Activitycoefficient
Temperature(K)
0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
0.9
298.15 328.15 358.15 388.15
Activitycoefficient
Temperature(K)
0
0.1
0.2
0.3
0.4
0.5
0.6
298.15 328.15 358.15 388.15
Activitycoefficient
Temperature(K)
0
0.1
0.2
0.3
0.4
0.5
0.6
298.15 328.15 358.15 388.15
Activitycoefficient
Temperature(K)
Figure 4-1: Variation of activity coefficients with temperature for the Alkane family in Methyl Palmitate for a) Original
UNIFAC; b) Modified UNIFAC Bastos; c) Modified UNIFAC Larsen; Methyl Linolenate for d) Original UNIFAC; e) Modified
UNIFAC Bastos; f) Modified UNIFAC Larsen
6. a) d)
b) e)
a) f)
Figure 4-2: The effect of temperature variation on the Alkane family in Methyl Stearate for
a) Original UNIFAC b) Modified UNIFAC Bastos; c) Modified UNIFAC Larsen; Methyl ate
for d) Original UNIFAC; e) Modified UNIFAC Bastos; f) Modified UNIFAC Larsen.
0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
298.15 328.15 358.15 388.15
Activitycoefficient
Temperature(K)
0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
298.15 328.15 358.15 388.15
Activitycoefficient
Temperature(K)
0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
0.9
298.15 328.15 358.15 388.15
Activitycoefficient
Temperature(K)
0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
0.9
298.15 328.15 358.15 388.15
Activitycoefficient
Temperature(K)
0
0.1
0.2
0.3
0.4
0.5
0.6
298.15 328.15 358.15 388.15
Activitycoefficient
Temperature(K)
0
0.1
0.2
0.3
0.4
0.5
0.6
298.15 328.15 358.15 388.15
Activitycoefficient
Temperature(K)
Figure 4-2: Variation of activity coefficients with temperature for the Alkane family in Methyl Stearate for a) Original UNIFAC;
b) Modified UNIFAC Bastos; c) Modified UNIFAC Larsen; Methyl Oleate for d) Original UNIFAC; e) Modified UNIFAC
Bastos; f) Modified UNIFAC Larsen
7. From Figures 4-1 and 4-2, it is evident that most of the
ester/alkane interactions show an increase in activity
coefficient as the temperature increased. 1-2 Dibromoethane
yielded the lowest activity coefficients as the temperature
increased. The activity coefficients of the halogenated
hydrocarbons are relatively unaffected by the changes in
temperature - as reflected by their “flat” graphs (very small
variations in activity coefficient as the temperature increased).
1-2 Dibromoethane had lower activity coefficients than 1-2
dichloroethane. This is due to the uneven distribution of the
chlorine molecules around 1-2 dichloroethane, which results in
the localisation of the negative charges around these atoms,
thus rendering the 1-2 dibromoethane molecule to be more
polar. This localisation of negative charge has a hindering
effect on the solubility of the 1-2 dibromoethane molecules in
FAMEs, which can be attributed to increased repulsive Van
der Waals forces. Therefore, the charge distribution of the 1-2
dibromoethane molecule is more balanced and the polarity is
favourable for absorption when compared to the 1-2
dichloroethane molecule. The chlorine molecule has a higher
electronegativity when compared to the bromine molecule.
The outer electrons of the chlorine molecule are also closer to
the nucleus therefore a higher bond disassociation energy has
to be overcome for the molecules to interact. Thus, 1-2
dibromoethane yielded lower activity coefficients than 1-2
dichloroethane throughout the temperature range.
The infinite dilution activity coefficients increased with an
increase in non-polar hydrocarbon chain length, with heptane
having higher activity coefficients than hexane across the
temperature range. This can be attributed to an increase in the
Van der Waals forces between solute-solute interactions as the
molecular weight is increased. Therefore, increased energy is
required to break the solute-solute bonds to allow for bonding
of the solvent to occur.
The esters with a lower carbon count (shorter chained esters)
had higher activity coefficients when compared to the esters
with a higher carbon count (longer chained esters) across the
temperature range. Therefore, as the solvent increases in size
the surface area proportionately increases, which affects the
intensity of the London dispersion forces of the solvent
molecule, thus resulting in an increased attraction for the
solute molecules as the solvent size was increased. This was
also due to the number of available sites for solute/solvent
interaction to occur which was favourable with the longer
chained esters. This is evident as methyl stearate had lower
activity coefficients than methyl palmitate with both being
saturated esters with no double bonding.
Methyl oleate-alkane interactions yielded lower activity
coefficients than methyl linolenate/alkane interactions and the
activity coefficients decreased even lower with methyl stearate,
with all three esters containing 19 carbon atoms. Therefore,
the activity coefficient values increase with an increase in the
amount of unsaturated double bonds in the ester hydrocarbon
chain across the temperature range. Thus, the solubility
decreased with the increase in the degree of solvent
unsaturation for the alkane family. This is due to the thermal
stability of saturated esters which have higher melting points
than unsaturated esters. Saturated esters have a more “linear”
structure due to the single bonds (C-C) in the hydrocarbon tail,
so they pack closely together. Unsaturated esters have “kinks”
due to the double bonds between the carbons (C=C), therefore
they do not pack together as closely. This causes the
unsaturated esters to break-up more easily when the
temperature is increased despite having double bonded carbon
atoms which have a higher bond dissociation energy than that
of single bonded carbons. Thus, less energy is required to
cause separation between the molecules.
B. Alkenes
Figs 4-3 and 4-4 show negligible influence of temperature of
VOCs – biodiesel interactions. Alkenes are less soluble than
akanes with thiophene being the most soluble. Thiophene
(C4H4S) is a heterocyclic compound which consists of a five
membered ring. Thiophene is considered to be an aromatic
although the degree of aromaticity is less than that of benzene.
The electron pairs on the sulphur (C-S-C) are significantly
delocalised and readily available for bonding. The molecule
also has a small surface area and is flat with a bond angle of 93
degrees at the sulphur and 114 degrees at the two carbons,
which makes it possible for ease of interaction with the
solvent, therefore accounting for the lower activity
coefficients.
From Figures 4-3 and 4-4, it is evident that naphthalene had
the highest activity coefficient and varied to a small degree
with an increase in temperature. The naphthalene molecule
can be viewed as a fusion of a pair of benzene rings, although
unlike the benzene molecule the carbon-carbon (C-C) bonds
are not the same length. This coupled with the high boiling
temperature of 170-230o
C, accounts for the stability in the
studied temperature range.
The naphthalene thermal stability was because of the benzene
molecule, where the double bonds of the solutes tend to
polarize the double bonds of the solvent molecules. In
benzene there are three pi bonds located in the hexagonal ring
in an alternate manner. These pi bonds get delocalised in the
ring and make the molecule thermally stable. An increase in
the number of double bonds in the solvent results in decreased
polarizability, therefore the solubility decreases with an
increase in the degree of solvent unsaturation.
8. a) d)
b) e)
c) f)
0
0.2
0.4
0.6
0.8
1
1.2
298.15 328.15 358.15 388.15
Activitycoefficient
Temperature(K)
0
0.2
0.4
0.6
0.8
1
1.2
298.15 328.15 358.15 388.15
Activitycoefficient
Temperature(K)
0
0.2
0.4
0.6
0.8
1
1.2
1.4
298.15 328.15 358.15 388.15
Activitycoefficient
Temperature(K)
0
0.2
0.4
0.6
0.8
1
1.2
298.15 328.15 358.15 388.15
Activitycoefficient
Temperature(K)
0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
298.15 328.15 358.15 388.15
Activitycoefficient
Temperature(K)
0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
298.15 328.15 358.15 388.15
Activitycoefficient
Temperature(K)
Figure 4-3: Variation of activity coefficients with temperature for the Alkene family in Methyl Palmitate for a) Original
UNIFAC; b) Modified UNIFAC Bastos; c) Modified UNIFAC Larsen; Methyl Linolenate for d) Original UNIFAC; e) Modified
UNIFAC Bastos; f) Modified UNIFAC Larsen
9. a) d)
b) e)
c) f)
Figure 4-4: The effect of temperature variation on the Alkene family in Methyl Stearate for
a) Original UNIFAC b) Modified UNIFAC Bastos; c) Modified UNIFAC Larsen; Methyl
Oleate for d) Original UNIFAC; e) Modified UNIFAC Bastos; f) Modified UNIFAC Larsen.
0
0.2
0.4
0.6
0.8
1
298.15 328.15 358.15 388.15
Activitycoefficient
Temperature(K)
0
0.2
0.4
0.6
0.8
1
298.15 328.15 358.15 388.15
Activitycoefficient
Temperature(K)
0
0.2
0.4
0.6
0.8
1
1.2
298.15 328.15 358.15 388.15
Activitycoefficient
Temperature(K)
0
0.2
0.4
0.6
0.8
1
1.2
298.15 328.15 358.15 388.15
Activitycoefficient
Temperature(K)
0
0.1
0.2
0.3
0.4
0.5
0.6
298.15 328.15 358.15 388.15
Activitycoefficient
Temperature(K)
0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
298.15 328.15 358.15 388.15
Activitycoefficient
Temperature(K)
Figure 4-4: Variation of activity coefficients with temperature for the Alkene family in Methyl Stearate for a) Original UNIFAC;
b) Modified UNIFAC Bastos; c) Modified UNIFAC Larsen; Methyl Oleate for d) Original UNIFAC; e) Modified UNIFAC
Bastos; f) Modified UNIFAC Larsen
10. Saturated esters have a more “linear” structure due to the
single bonds (C-C) in the hydrocarbon tail, so they pack
closely together. Unsaturated esters have “kinks” due to the
double bonds between the carbons (C=C), therefore they do
not pack together closely. This naturally causes the
unsaturated esters to break-up more easily despite having
double bonded carbon atoms which have a higher bond
dissociation energy than that of single bonded carbons. Thus,
less energy is required to cause separation between the
molecules.
Esters with a lower carbon count had higher activity
coefficients when compared to the esters with a higher carbon
count across the temperature range. This means that as the
solvent increases in size the surface area will proportionately
increase, which will affect the intensity of the London
dispersion forces of the solvent molecule, therefore resulting in
an increased attraction for the solute molecules as the solvent
size was increased. This was also due to the number of
available sites for solute/solvent interaction to occur which
was more favourable with the longer chained esters.
C. Amines
The amine family showed little variation in activity coefficient
as the temperature was increased. This is represented by the
relatively “flat” graphs, Figs 4-5 and 4-6. With regards to the
amine family, triethanolamine was the most suitable and the
effect of temperature was negligible. Triethanolamine
(C6H15NO3) is a viscous organic compound that is both a triol
and a tertiary amine. The activity coefficients for tertiary
amines (Trimethylamine) were lower than that of the
secondary mines (Dimethylamine), indicating that tertiary
amines are more soluble in ester solvents. This was due to the
hydrogen bonding that was readily available in tertiary amines
for interactions with ester solvents. In the case of
triethanolamine the hydrogen bonding ability is increased due
to the presence of the hydroxyl groups. In the triethanolamine
molecule the (N-OH) bond is a much weaker bond with a bond
disassociation energy of 201kJ/mol. Due to the low
electronegativity of the nitrogen atom, the hydrogen molecule
is available for bonding with the solvent. Nitrogen has a half
filled p-orbital containing three electrons, which is more stable
than oxygen’s electron configuration, which has an incomplete
p-orbital containing four electrons. Therefore, less energy was
required to break the solute-solute bonds, allowing for solute-
solvent bonds to form, thereby accounting for the lower
activity coefficients.
The number of double bonds in the solvent resulted in
decreased polarizability, therefore the solubility decreased.
Saturated esters have a more “linear” structure due to the
single bonds (C-C) in the hydrocarbon tail, and therefore pack
closely together. Unsaturated esters have “kinks” due to the
double bonds between the carbons (C=C), therefore they do
not pack together closely. Therefore the unsaturated esters
break-up more easily despite having double bonded carbon
atoms which have a higher bond dissociation energy than that
of single bonded carbons. Thus, less energy is required to
cause separation between the molecules.
Amine - methyl stearate is the most soluble among the amine
family of VOCs, Fig. 4.6. VOCs solubility increases with
increase in esters molecular weight. As the solvent increases
in size, the surface area also increases affecting the intensity of
the London dispersion forces of the solvent molecule, thus
enhancing solute solubility. The number of available sites for
solute / solvent interaction increase with increase in solvent
molecular weight.
Amines are bulky molecules and this increases the surface
area available for solute–solvent London dispersion
interactions to occur. Trimethylamine is more soluble than
triethylamine due to its smaller size and is also a H-bond
acceptor, and therefore has a higher degree of polarizability.
11. a) d)
b) e)
a) f)
0
0.2
0.4
0.6
0.8
1
1.2
298.15 328.15 358.15 388.15
Activitycoefficient
Temperature(K)
0
0.2
0.4
0.6
0.8
1
1.2
298.15 328.15 358.15 388.15
Activitycoefficient
Temperature(K)
0
0.2
0.4
0.6
0.8
1
1.2
1.4
298.15 328.15 358.15 388.15
Activitycoefficient
Temperature(K)
0
0.2
0.4
0.6
0.8
1
1.2
298.15 328.15 358.15 388.15
Activitycoefficient
Temperature(K)
0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
298.15 328.15 358.15 388.15
Activitycoefficient
Temperature(K)
0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
298.15 328.15 358.15 388.15
Activitycoefficient
Temperature(K)
Figure 4-5: Variation of activity coefficients with temperature for the Amine family in Methyl Palmitate for a) Original
UNIFAC; b) Modified UNIFAC Bastos; c) Modified UNIFAC Larsen; Methyl Linolenate for d) Original UNIFAC; e) Modified
UNIFAC Bastos; f) Modified UNIFAC Larsen
12. a) d)
b) e)
a) f)
Figure 4-6: The effect of temperature variation on the Amine family in Methyl Stearate for a)
Original UNIFAC b) Modified UNIFAC Bastos; c) Modified UNIFAC Larsen; Methyl
Oleate for d) Original UNIFAC; e) Modified UNIFAC Bastos; f) Modified UNIFAC Larsen.
0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
298.15 328.15 358.15 388.15
Activitycoefficient
Temperature(K)
0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
298.15 328.15 358.15 388.15
Activitycoefficient
Temperature(K)
0
0.2
0.4
0.6
0.8
1
298.15 328.15 358.15 388.15
Activitycoefficient
Temperature(K)
0
0.2
0.4
0.6
0.8
1
298.15 328.15 358.15 388.15
Activitycoefficient
Temperature(K)
0
0.1
0.2
0.3
0.4
0.5
0.6
298.15 328.15 358.15 388.15
Activitycoefficient
Temperature(K)
0
0.1
0.2
0.3
0.4
0.5
0.6
298.15 328.15 358.15 388.15
Activitycoefficient
Temperature(K)
Figure 4-6: Variation of activity coefficients with temperature for the Amine family in Methyl Stearate for a) Original UNIFAC;
b) Modified UNIFAC Bastos; c) Modified UNIFAC Larsen; Methyl Oleate for d) Original UNIFAC; e) Modified UNIFAC
Bastos; f) Modified UNIFAC Larsen
13. D. Alcohols
a) d)
b) e)
Figure 4-7: The effect of temperature variation on the Alcohol family in Methyl Palmitate
for a) Original UNIFAC b) Modified UNIFAC Bastos; c) Modified UNIFAC Larsen; Methyl
Linolenate for d) Original UNIFAC; e) Modified UNIFAC Bastos; f) Modified UNIFAC
Larsen.
0
0.05
0.1
0.15
0.2
0.25
0.3
298.15 328.15 358.15 388.15
Activitycoefficient
Temperature(K)
0
0.05
0.1
0.15
0.2
0.25
0.3
298.15 328.15 358.15 388.15
Activitycoefficient
Temperature(K)
0
0.05
0.1
0.15
0.2
0.25
0.3
0.35
298.15 328.15 358.15 388.15
Activitycoefficient
Temperature(K)
0
0.05
0.1
0.15
0.2
0.25
298.15 328.15 358.15 388.15
Activitycoefficient
Temperature(K)
0
0.05
0.1
0.15
0.2
298.15 328.15 358.15 388.15
Activitycoefficient
Temperature(K)
0
0.05
0.1
0.15
0.2
0.25
298.15 328.15 358.15 388.15
Activitycoefficient
Temperature(K)
c) d)
Figure 4-7: Variation of activity coefficients with temperature for the Alcohol family in Methyl Palmitate for a) Original
UNIFAC; b) Modified UNIFAC Bastos; c) Modified UNIFAC Larsen; Methyl Linolenate for d) Original UNIFAC; e) Modified
UNIFAC Bastos; f) Modified UNIFAC Larsen
14. a) d)
b) e)
c) f)
Figure 4-8 The effect of temperature variation on the Alcohol family in Methyl Stearate for
a) Original UNIFAC b) Modified UNIFAC Bastos; c) Modified UNIFAC Larsen; Methyl
Oleate for d) Original UNIFAC; e) Modified UNIFAC Bastos; f) Modified UNIFAC Larsen.
0
0.05
0.1
0.15
0.2
298.15 328.15 358.15 388.15
Activitycoefficient
Temperature(K)
0
0.05
0.1
0.15
0.2
0.25
298.15 328.15 358.15 388.15
Activitycoefficient
Temperature(K)
0
0.05
0.1
0.15
0.2
0.25
298.15 328.15 358.15 388.15
Activitycoefficient
Temperature(K)
0
0.05
0.1
0.15
0.2
0.25
0.3
298.15 328.15 358.15 388.15
Activitycoefficient
Temperature(K)
0
0.05
0.1
0.15
0.2
298.15 328.15 358.15 388.15
Activitycoefficient
Temperature(K)
0
0.05
0.1
0.15
0.2
298.15 328.15 358.15 388.15
Activitycoefficient
Temperature(K)
Figure 4-8: Variation of activity coefficients with temperature for the Alcohol family in Methyl Stearate for a) Original
UNIFAC; b) Modified UNIFAC Bastos; c) Modified UNIFAC Larsen; Methyl Oleate for d) Original UNIFAC; e) Modified
UNIFAC Bastos; f) Modified UNIFAC Larsen
15. Solubility of most alcohols in esters decrease with an increase
in temperature, Figs 4-7 and 4-8. Ethylene glycol was the
most soluble in the temperature range studied. Glycols are
polar with two hydroxyl ends which promote high solubility of
compounds with large dipole moments. The high solubility of
glycols is due to the fact that “like will dissolve in like” and
mainly due to the polarity effects.
Methyllinoleate – ethylene glycol was the least soluble and this
can be attributed to the highly electronegative hydroxyl groups
which allow for hydrogen bonding with carbonyl groups
(C=O). Cyclohexanol ((CH2)5CHOH) was the least soluble
alcohol due to its bulkness.
Methyl stearate has the highest affinity for esters and hence the
most thermodynmically suitable for their abatement from
waste gas streams. Polarizability decreases with increase in
number of double bonds reducing the solubility. This can be
attributed to the “linear” structure of the saturated esters
allowingclose packing . Unsaturated esters have “kinks” due
to the double bonds between the carbons (C=C) packing
together less closely. Solubility increases with increase in
ester molecular weight due to the enhancement of solvent
London dispersion forces.
E. Carboxylic Acids
Solubility decreases with increase in temperature for all
carboxylic acid / ester systems, Figs 4-9 and 4-10. Butyric
acid is the most soluble in the family group. The solubility of
organic acids decrease with an increase in the molecular
weight of the solute. The is due to the increase in the Van der
Waals forces between solute-solute interactions as the size of
the molecules increased. Thus large amount of energy is
required to overcome the attractive forces in order to allow for
solute – solvent interactions. The carboxyl group (–COOH)
in organic acids contain a carbonyl (C=O) with a bond
disassociation energy of 802 kJ/mol, and a hydroxyl group (-
OH) with a bond disassociation energy of 460 kJ/mol. Thus,
the weaker bond is the hydroxyl group (-OH), with organic
acids being H-bond donors.
The solubility decreases with an increase in unsaturation of the
solvent (ester) molecule. Saturated esters are more “linear”
allowing for close packing. Organic acids are H-bond donors
and polar, therefore the solubility of the ester/organic acid
interactions decreases with the degree of solvent unsaturation.
The increase in activity coefficients was as a result of a
decrease in the hydrogen bonds capability to polarize the
double bonds in the solvent with increase in temperature.
16. a) d)
b) e)
c) f)
Figure 4-9: The effect of temperature variation on the Carboxylic Acid family in Methyl
Palmitate for a) Original UNIFAC b) Modified UNIFAC Bastos; c) Modified UNIFAC
Larsen; Methyl Linolenate for d) Original UNIFAC; e) Modified UNIFAC Bastos; f)
Modified UNIFAC Larsen.
0
0.1
0.2
0.3
0.4
0.5
0.6
298.15 328.15 358.15 388.15
Activitycoefficient
Temperature(K)
0
0.1
0.2
0.3
0.4
0.5
0.6
298.15 328.15 358.15 388.15
Activitycoefficient
Temperature(K)
0
0.1
0.2
0.3
0.4
0.5
0.6
298.15 328.15 358.15 388.15
Activitycoefficient
Temperature(K)
0
0.1
0.2
0.3
0.4
0.5
0.6
298.15 328.15 358.15 388.15
Activitycoefficient
Temperature(K)
0
0.05
0.1
0.15
0.2
0.25
0.3
298.15 328.15 358.15 388.15
Activitycoefficient
Temperature(K)
0
0.1
0.2
0.3
0.4
0.5
298.15 328.15 358.15 388.15
Activitycoefficient
Temperature(K)
Figure 4-9: Variation of activity coefficients with temperature for the Carboxylic Acid family in Methyl Palmitate for a) Original
UNIFAC; b) Modified UNIFAC Bastos; c) Modified UNIFAC Larsen; Methyl Linolenate for d) Original UNIFAC; e) Modified
UNIFAC Bastos; f) Modified UNIFAC Larsen
17. a) d)
b) e)
c) f)
Figure 4-10: The effect of temperature variation on the Carboxylic Acid family in Methyl
Stearate for a) Original UNIFAC b) Modified UNIFAC Bastos; c) Modified UNIFAC
Larsen; Methyl Oleate for d) Original UNIFAC; e) Modified UNIFAC Bastos; f) Modified
UNIFAC Larsen.
0
0.05
0.1
0.15
0.2
0.25
0.3
0.35
0.4
0.45
298.15 328.15 358.15 388.15
Activitycoefficient
Temperature(K)
0
0.1
0.2
0.3
0.4
0.5
298.15 328.15 358.15 388.15
Activitycoefficient
Temperature(K)
0
0.1
0.2
0.3
0.4
0.5
298.15 328.15 358.15 388.15
Activitycoefficient
Temperature(K)
0
0.1
0.2
0.3
0.4
0.5
0.6
298.15 328.15 358.15 388.15
Activitycoefficient
Temperature(K)
0
0.05
0.1
0.15
0.2
0.25
298.15 328.15 358.15 388.15
Activitycoefficient
Temperature(K)
0
0.05
0.1
0.15
0.2
0.25
298.15 328.15 358.15 388.15
Activitycoefficient
Temperature(K)
Figure 4-10: Variation of activity coefficients with temperature for the carboxylic acid family in Methyl Stearate for a) Original
UNIFAC; b) Modified UNIFAC Bastos; c) Modified UNIFAC Larsen; Methyl Oleate for d) Original UNIFAC; e) Modified
UNIFAC Bastos; f) Modified UNIFAC Larsen
18. V.CONCLUSION
This paper presents the vapour liquid equilibrium data for 25
volatile organic compounds in four biodiesels using the using
the Original UNIFAC: Fredenslund et al, 1975; Modified
UNIFAC: Bastos et al, 1988 and lastly the Modified UNIFAC
(Larsen et al., 1981). The UNIFAC procedure can reliably
predict phase equilibrium data within the temperature range
and is time and cost saving. Biodiesel is a good absorption
medium for volatile organic compounds considered in this
work because of the low activity coefficients.
ACKNOWLEDGMENT
The authors wish to acknowledge University of Johannesburg
and the CSIR for technical and financial support.
REFERENCES
[1] Activity coefficient [online]. 2012 [cited 2012 Sept]. Available from
URL: http://www.wikipedia.com
[2] H.O. Paksoy, S. Örnektekin, B. Bilgin, Y. Demirel,. The Performance of
UNIFAC and Related Group Contribution Models Part I. Prediction of
Infinite Dilution Activity Coefficients, Thermochimica Acta, 1996,
Vol. 287, 235–249
[3] Bastos, J.C. Soares,. M. E., Medina, A. G. Infinite Dilution Activity
Coefficients by UNIFAC Group Contribution. Ind. Eng. Chem. Res.
1988, 27, 116
[4] N.P. Cheremisinoff,. Handbook of Air Pollution Prevention and
Control, Elsevier Science, 2002
[5] K. Bay, H. Wanko, J. Ulrich,. Absorption of Volatile Organic
Compounds in Biodiesel: Determination of Infinite Dilution Activity
Coefficients by Headspace Gas Chromatography, Chem. Eng. Res.
Des,2006, Vol. 84, 22–27
[6] Wilson A, Canas M, Uriel EG, Julian D., Comparison of different cubic
equations of state and combination rules for predicting residual
chemical potential of binary and ternary Lennard–Jones mixtures:
Solid-supercritical fluid phase equilibria. Fluid Phase Equilibria 2005,
42–50
[7] Biodiesel [online]. 2012 [cited 2012 Sept]. Available from URL:
http://www.wikipedia.com
[8] Jianbo H, Zexue D, Zhong Tang, E Min. Study on the Solvent Power of
a New Green Solvent: Biodiesel. Ind. Eng. Chem. Res. 2004, 43, 7928-
7931
[9] Voustas E.C, D.P Tassios., Prediction of infinite dilution activity
coefficient in binary mixtures with the UNIFAC. A critical evaluation.
Ind Eng. Chem Res.1996,35,1438-1445
[10] Herber RP, Soares RP,. Assessing the reliability of predictive activity
coefficient models for molecules consisting of several groups. Braz. J.
Chem Eng 2013, Vol 30, 1
[11] Activity coefficient [online]. 2012 [cited 2012 Sept]. Available from
URL: http://www.wikipedia.com
[12] H.K Hansen, P. Rasmussen, A. Fredenslund, M. Schiller, J. Gmehling,.
Vapor-Liquid Equilibria by UNIFAC Group Contribution. 5. Revision
and Extension, Ind. Eng. Chem., 1991, Vol. 30,2355–2358
[13] Fredenslund, A. Jones, R. L., Prausnitz,. J. M. Group Contribution
Estimation of Activity Coefficients in Non-ideal Liquid Mixtures.
AIChE J. 1975, 21, 1086
[14] Soave Redlich Kwong EOS- Department of Energy and Mineral
processing. [online]. 2012 [cited 2012 Sept]. Available from URL:
http://www.eme.psu.edu
[15] Somaieh S, Marc A. Dub,. Biodiesel: a green polymerization solvent.
The Royal Society of Chemistry, Green Chem., 2008, 10, 321–326
[16] Larsen, B. L. Rasmussen, P. Fredenslund,. UNIFAC Parameter Table
for Prediction of Liquid-Liquid Equilibria. Ind. Eng. Chem. Process
Des. Dev. 1981, 20, 331
[17] H.O. Paksoy, S. Örnektekin, B. Bilgin, Y. Demirel,. The Performance
of UNIFAC and Related Group Contribution Models Part I. Prediction
of Infinite Dilution Activity Coefficients, Thermochimica Acta, 1996,
Vol. 287, 250
[18] Bastos, J.C. Soares,. M. E., Medina, A. G. Infinite Dilution Activity
Coefficients by UNIFAC Group Contribution. Ind. Eng. Chem. Res.
1988, 27, 114
[19] Graham Solomoins TX,. Organic Chemistry Solomons 6th Edition.
August, 1995, Chap 14, 614-654
[20] M Trevor, Developments and applications in Solubility, The Royal
Society of Chemistry, 2007, 116-146
S. Ramdharee: The author was born in 1984 in
Newcastle, Kwa-Zulu Natal, South Africa. This
author became a member of ECSA (Engineering
Council of South Africa) in 2010. He successfully
completed a NDip:Chemical Engineering at Durban
University of Technology, Kwa-Zulu Natal, South
Africa in 2007. After which he pursued a BTech:
Chemical Engineering at the same institution in
2008, graduating Cum Laude, with the Deans Merit award for being the top
student in year 2008, and also received the award for Mathematics, Statistics
and Physics Year 2008. Currently he is studying towards a MTech: Chemical
Engineering at the University of Johannesburg, Gauteng, South Africa and
completing the PMP®
certification with the American based Project
Management Institute.
He has worked at African Amines: Junior production engineer; Karbochem
ltd: Junior projects engineer; International Furan Technology: Chemical
engineer; Sasol Synfuels: Senior as-built auditor; Sasol synfuels: Process
technologist; National Cleaner Production Centre of South Africa: Regional
project manager: Energy systems optimization.
Mohamed Belaid obtained Msc Chemical
Engineering, UKZN South Africa (2001), BSC
Industrial Chemical Engineering, Engineering of
organic processes (1994), University of Blida,
Algeria, currently is doing PhD at Wits University
(South Africa). Mohamed is a senior lecturer at the
University of Johannesburg, worked as a lecturer at
the University of Kwazulu Natal for over 8 years, a
quality control Engineer for Energy Engineering PTY
(South Africa) for two years and Elangeni oil and soap (South Africa) for a
period of two years, process Engineer (SAIDAL, antibiotic company, Algeria)
for one year.
Mr. Belaid is a member of SAIChE (2003, South Africa institute of
Chemical Engineers) and He is a research member at the department of
Chemical Engineering, authored and contributed to various publications, both
journals and conferences proceedings in environmental engineering,
separation processes, mineral processing, fluidized beds, activated carbon and
engineering Education
Edison Muzenda is a Full Professor of Chemical
and Petroleum Engineering, and Head of
Chemical, Materials and Metallurgical
Engineering Department at Botswana
International University of Science and
Technology. He is also a Visiting Professor in the
Department of Chemical Engineering, Faculty of
Engineering and Built Environment, University of
Johannesburg. He was previously a Full Professor
of Chemical Engineering, the Research and Postgraduate Coordinator as well
as Head of the Environmental and Process Systems Engineering and
Bioenergy Research Groups at the University of Johannesburg. Professor
Muzenda holds a PhD in Chemical Engineering from the University of
Birmingham, United Kingdom. He has more than 16 years’ experience in
academia which he gained at various institutions including the National
University of Science and Technology, Zimbabwe, University of
Birmingham, University of Witwatersrand, and most importantly the
19. University of Johannesburg. Through his academic preparation and career, He
has held several management and leadership positions such as member of the
student representative council, research group leader, university committees’
member, staff qualification coordinator as well as research and postgraduate
coordinator. Edison’s teaching interests and expertise are in unit operations,
multi-stage separation processes, environmental engineering, chemical
engineering thermodynamics, professional engineering skills, research
methodology as well as process economics, management and optimization.
He is a recipient of several awards and scholarships for academic excellence.
His research interests are in green energy engineering, integrated waste
management, volatile organic compounds abatement and as well as phase
equilibrium measurement and computation. He has contributed to more than
280 international peer reviewed and refereed scientific articles in the form of
journals, conferences books and book chapters. He has supervised more than
30 postgraduate students and over 250 Honours and BTech research students.
He serves as reviewer for a number of reputable international conferences and
journals. Edison is a member of several academic and scientific organizations
including the Institute of Chemical Engineers, UK and South African Institute
of Chemical Engineers. He is an Editor for a number of Scientific Journals
and Conferences. He has organized and chaired several international
conferences. He currently serves as an associate Editor of the South African
Journal of Chemical Engineering. His current research activities are mainly
focused on WASTE to ENERGY projects particularly biowaste to energy for
vehicular application in collaboration with SANEDI and City of
Johannesburg PIKITUP as well as waste tyre and plastics utilization for fuels
and valuable chemicals in collaboration with Recycling and Economic
Development Initiative of South Africa (REDISA). He has been in the top 3
and 10 research output contributors in the faculty of Engineering and the
Built Environment and the University of Johannesburg respectively since
2010. In 2013, Prof Muzenda was the top and number 2 research output
contributor in the Faculty of Engineering and Built Environment, and
University of Johannesburg respectively. Edison is a member of the South
African Government Ministerial Advisory Council on Energy and Steering
Committee of City of Johannesburg – University of Johannesburg Biogas
Digester Project.