The most common method of preserving raw hidesis brine curing with sodium chloride. However, thisprocess has three important disadvantages: first, thelength of time that it takes, which is a minimum of18 hours; second, the insufficient degree of curingreached in some hides due to an overload andpossibly the low efficiency of the brine raceway; andfinally, the environmental impact associated withthe discharge of large quantities of electrolytes in thesoaking step. Our long term goal is to address allthree issues. Initially, we have carried out a studyof the salt uptake and its diffusion mechanism inorder to attempt a reduction in the curing time. Acontinuous reaction mathematical model of a closedone dimensional system that describes the diffusionof sodium chloride in the hide during the curingprocess was chosen in the search for the optimumbrine curing conditions such as the optimum brineconcentration and percent float. The effect of thesetwo parameters on the values of transport coefficient
was reported. Brine diffusion into the hide wastracked by measurement of the chloride concentrationof the residual brine solution. In addition, a piece ofhide was cured with a fluorescently labeled brinesolution and analyzed by means of epifluorescentmicroscopy for direct visualization of the sodiumlocation within the hide.
IJERA (International journal of Engineering Research and Applications) is International online, ... peer reviewed journal. For more detail or submit your article, please visit www.ijera.com
This document summarizes an investigation into the effects of palladium nanoparticles (PdNPs), pH, and temperature on the reduction of hexavalent chromium (CrVI) to its less toxic form CrIII. Key findings include:
1) The optimal conditions for the reduction reaction were pH 4 and 45°C temperature.
2) Reaction kinetics followed pseudo-first order behavior, indicating a linear decrease in CrVI over time.
3) PdNPs catalyzed the reaction, decreasing the activation energy by 20±10 kJ/mol and increasing the rate constant over an order of magnitude.
4) Under optimal conditions, a 26% reduction of CrVI was achieved.
IOSR Journal of Applied Physics (IOSR-JAP) is an open access international journal that provides rapid publication (within a month) of articles in all areas of physics and its applications. The journal welcomes publications of high quality papers on theoretical developments and practical applications in applied physics. Original research papers, state-of-the-art reviews, and high quality technical notes are invited for publications.
Carbonate removal from coastal sediments for the determination of organic c a...Mahbubul Hassan
The document compares two methods for removing inorganic carbon from samples to isolate organic carbon for analysis: the aqueous method using hydrochloric acid (HClaq) and the vaporous method using hydrochloric acid vapor (HClvap). It evaluates the methods based on their ability to have low blank levels, efficiently remove dolomite, yield accurate measurements of organic carbon percentage and isotopic signatures (δ13C and Δ14C). The vaporous method met all criteria if samples were not overexposed to acid. The aqueous method gave similar results but was less reliable and consistently underestimated organic carbon percentage. Optimal acid exposure times need to be determined for each sample type to obtain the most accurate isotopic measurements.
Removal of cadmium from aqueous solution using cobalt silicate precipitation ...IJSIT Editor
This document discusses the removal of cadmium from aqueous solutions using cobalt silicate precipitation tubes (CoSPT) as an adsorbent. CoSPT was synthesized through a "silica garden" process and found to be an effective adsorbent for cadmium. Batch adsorption studies were conducted to determine the effect of contact time, adsorbent dose, initial cadmium concentration, temperature, and pH. Experimental data fit the Langmuir and Freundlich isotherm models well. Kinetic studies showed that the pseudo-second order model provided the best fit. The maximum adsorption capacity of CoSPT for cadmium was estimated to be 319 mg/g based on
A new Schiff base 4-chlorophenyl)methanimine
(6R,7R)-3-methyl-8-oxo-7-(2-phenylpropanamido)-5-thia-1-
azabicyclo[4.2.0]oct-2-ene-2-carboxylate= (HL)= C23H20
ClN3O4S) has been synthesized from β-lactam antibiotic
(cephalexin mono hydrate(CephH)=(C16H19N3O5S.H2O) and 4-
chlorobenzaldehyde . Figure(1) Metal mixed ligand complexes
of the Schiff base were prepared from chloride salt of
Fe(II),Co(II),Ni(II),Cu(II),Zn(II) and Cd (II), in 50% (v/v)
ethanol –water medium (SacH ) .in aqueous ethanol(1:1)
containing and Saccharin(C7H5NO3S) = sodium hydroxide.
Several physical tools in particular; IR, CHN, 1H NMR, 13C
NMR for ligand and melting point molar conductance, magnetic
moment. and determination the percentage of the metal in the
complexes by flame(AAS). The ligands and there metal
complexes were screened for their antimicrobial activity against
four bacteria (gram + ve) and (gram -ve) {Escherichia coli,
Pseudomonas aeruginosa, Staphylococcus aureus and Bacillus}.
The proposed structure of the complexes using program, Chem
office 3D(2006). The general formula have been given for the
prepared mixed ligand complexes Na2[M(Sac)3(L)], M(II) = Fe
(II), Co(II) , Ni(II), Cu (II), Zn(II) , and Cd(II).
HL= C29H24 ClN3O4S, L= C29H23 ClN3O4S -.
Film pore diffusion modeling for sorption of azo dye on to exfoliated graphit...Science Padayatchi
The document describes research on using exfoliated graphitic nanoplatelets (xGnPs) to adsorb the azo dye Acid Orange 7 from aqueous solutions. The effects of temperature, pH, and initial dye concentration on the adsorption process were studied. Kinetic data fit the pseudo-first-order and pseudo-second-order models well. Adsorption isotherms followed the Langmuir model. Analysis of the kinetics and isotherms provided insight into the adsorption mechanism and rate determining steps. The xGnPs were found to efficiently and effectively remove the acid dye from solutions through an exothermic adsorption process governed by chemical reaction kinetics.
Validation of an extraction technique based on tributyl phosphateNasir Othman
This document describes the validation of an extraction technique using tributyl phosphate (TBP) for the determination of lead (Pb) in water samples. The extraction was optimized at pH 9-11, shaking time of 2-5 minutes, and 0.04M nitric acid as the stripping agent. Validation criteria such as recovery, linearity, accuracy, precision, detection limits, and robustness were evaluated. The technique showed high accuracy with 100% recovery and good linearity (R2=0.9969). Precision was good with relative standard deviations below 20%. The method detection limit was 4.43 μg/L and limit of quantification was 14.75 μg/L. Application to water samples from six sites on the Lang
IJERA (International journal of Engineering Research and Applications) is International online, ... peer reviewed journal. For more detail or submit your article, please visit www.ijera.com
This document summarizes an investigation into the effects of palladium nanoparticles (PdNPs), pH, and temperature on the reduction of hexavalent chromium (CrVI) to its less toxic form CrIII. Key findings include:
1) The optimal conditions for the reduction reaction were pH 4 and 45°C temperature.
2) Reaction kinetics followed pseudo-first order behavior, indicating a linear decrease in CrVI over time.
3) PdNPs catalyzed the reaction, decreasing the activation energy by 20±10 kJ/mol and increasing the rate constant over an order of magnitude.
4) Under optimal conditions, a 26% reduction of CrVI was achieved.
IOSR Journal of Applied Physics (IOSR-JAP) is an open access international journal that provides rapid publication (within a month) of articles in all areas of physics and its applications. The journal welcomes publications of high quality papers on theoretical developments and practical applications in applied physics. Original research papers, state-of-the-art reviews, and high quality technical notes are invited for publications.
Carbonate removal from coastal sediments for the determination of organic c a...Mahbubul Hassan
The document compares two methods for removing inorganic carbon from samples to isolate organic carbon for analysis: the aqueous method using hydrochloric acid (HClaq) and the vaporous method using hydrochloric acid vapor (HClvap). It evaluates the methods based on their ability to have low blank levels, efficiently remove dolomite, yield accurate measurements of organic carbon percentage and isotopic signatures (δ13C and Δ14C). The vaporous method met all criteria if samples were not overexposed to acid. The aqueous method gave similar results but was less reliable and consistently underestimated organic carbon percentage. Optimal acid exposure times need to be determined for each sample type to obtain the most accurate isotopic measurements.
Removal of cadmium from aqueous solution using cobalt silicate precipitation ...IJSIT Editor
This document discusses the removal of cadmium from aqueous solutions using cobalt silicate precipitation tubes (CoSPT) as an adsorbent. CoSPT was synthesized through a "silica garden" process and found to be an effective adsorbent for cadmium. Batch adsorption studies were conducted to determine the effect of contact time, adsorbent dose, initial cadmium concentration, temperature, and pH. Experimental data fit the Langmuir and Freundlich isotherm models well. Kinetic studies showed that the pseudo-second order model provided the best fit. The maximum adsorption capacity of CoSPT for cadmium was estimated to be 319 mg/g based on
A new Schiff base 4-chlorophenyl)methanimine
(6R,7R)-3-methyl-8-oxo-7-(2-phenylpropanamido)-5-thia-1-
azabicyclo[4.2.0]oct-2-ene-2-carboxylate= (HL)= C23H20
ClN3O4S) has been synthesized from β-lactam antibiotic
(cephalexin mono hydrate(CephH)=(C16H19N3O5S.H2O) and 4-
chlorobenzaldehyde . Figure(1) Metal mixed ligand complexes
of the Schiff base were prepared from chloride salt of
Fe(II),Co(II),Ni(II),Cu(II),Zn(II) and Cd (II), in 50% (v/v)
ethanol –water medium (SacH ) .in aqueous ethanol(1:1)
containing and Saccharin(C7H5NO3S) = sodium hydroxide.
Several physical tools in particular; IR, CHN, 1H NMR, 13C
NMR for ligand and melting point molar conductance, magnetic
moment. and determination the percentage of the metal in the
complexes by flame(AAS). The ligands and there metal
complexes were screened for their antimicrobial activity against
four bacteria (gram + ve) and (gram -ve) {Escherichia coli,
Pseudomonas aeruginosa, Staphylococcus aureus and Bacillus}.
The proposed structure of the complexes using program, Chem
office 3D(2006). The general formula have been given for the
prepared mixed ligand complexes Na2[M(Sac)3(L)], M(II) = Fe
(II), Co(II) , Ni(II), Cu (II), Zn(II) , and Cd(II).
HL= C29H24 ClN3O4S, L= C29H23 ClN3O4S -.
Film pore diffusion modeling for sorption of azo dye on to exfoliated graphit...Science Padayatchi
The document describes research on using exfoliated graphitic nanoplatelets (xGnPs) to adsorb the azo dye Acid Orange 7 from aqueous solutions. The effects of temperature, pH, and initial dye concentration on the adsorption process were studied. Kinetic data fit the pseudo-first-order and pseudo-second-order models well. Adsorption isotherms followed the Langmuir model. Analysis of the kinetics and isotherms provided insight into the adsorption mechanism and rate determining steps. The xGnPs were found to efficiently and effectively remove the acid dye from solutions through an exothermic adsorption process governed by chemical reaction kinetics.
Validation of an extraction technique based on tributyl phosphateNasir Othman
This document describes the validation of an extraction technique using tributyl phosphate (TBP) for the determination of lead (Pb) in water samples. The extraction was optimized at pH 9-11, shaking time of 2-5 minutes, and 0.04M nitric acid as the stripping agent. Validation criteria such as recovery, linearity, accuracy, precision, detection limits, and robustness were evaluated. The technique showed high accuracy with 100% recovery and good linearity (R2=0.9969). Precision was good with relative standard deviations below 20%. The method detection limit was 4.43 μg/L and limit of quantification was 14.75 μg/L. Application to water samples from six sites on the Lang
This article describes the development and validation of a simple reverse phase HPLC method for the quantitative analysis of diazepam in pharmaceutical dosage forms. A C18 column with a mobile phase of acetonitrile, methanol and phosphate buffer at a flow rate of 1 mL/min was used to achieve good resolution and retention of diazepam at 6.23 minutes. The method was validated and found to be linear, precise, accurate, sensitive and robust for the analysis of diazepam in tablets with recoveries ranging from 99.4-100.3%.
Separation of calcium carbonate and barium sulphate from a mixed sludge prduc...Timothy Rukuni
South Africa is one of the first countries to implement full-scale mine water reclamation to drinking water quality. Reverse osmosis is already being used on full scale for desalination of mine water. However, with increased recycling of mine water, the result has been the increased generation of sludge. The Council for Scientific and Industrial Research (CSIR) has developed the Alkali-Barium-Carbonate (CSIR-ABC) process that can be used for neutralization and desalination of sulphate-rich effluents while recovering valuable by-products from the mixed sludges produced. A mixture of BaSO4 and CaCO3 sludge is produced as one of the by-products, which preferably needs to be separated into its components prior to thermal treatment. The aim of this study was to separate CaCO3 and BaSO4 from a CaCO3-BaSO4 mixed sludge through dissolution of CaCO3 as Ca(HCO3)2 in contact with CO2. Measured quantities of a simulated CaCO3-BaSO4 mixed sludge from the CSIR-ABC process were fed into a reactor vessel containing deionized water and pressurized CO2 was introduced. The effects of temperature and pressure with time were investigated while monitoring alkalinity, pH and calcium concentration. The findings of this study were: (1) The dissolution rate of CaCO3 was rapid i.e. from 0 to 2000mg/L in the first 20 minutes; (2) Ca(HCO3)2 had a high solubility of about 2 600 mg/L when in contact with CO2 at 1 atm., while BaSO4 was almost completely insoluble; (3) The solubility of Ca(HCO3)2 increased with decreasing temperature and increasing pressure; (4) CaCO3, after conversion to Ca(HCO3)2, was separated from BaSO4 in a CaCO3-BaSO4 mixed sludge; (5) Visual MINTEQ model is a powerful tool that can be used to predict the solubilities of CaCO3 and BaSO4 when contacted with CO2.
Characterization of mining tailings containing sulfides and carbonates applyi...Judson Arantes
Acid mine drainage (AMD) is the process resulting from the oxidation of sulfides exposed to the action of oxygen and water. The characterization of the minerals likely the formation and neutralization of AMD is important for the follow and evaluation of environmental impact. The analysis of X-ray diffraction (XRD) together with the Rietveld method is presented as a promising alternative to favor the identification and quantification of mineral phases. The results of the static test ANC achieved by accounting for carbonates consumed during the test, were correlated with the results obtained by the characterization techniques of X-ray diffraction (XRD) combined with the Rietveld method. The highest concentration of carbonate buffering found in AM2E, which may explain the static test results to be neutralizing for the sample. The major phases identified for both samples were aluminosilicates and quartz, with greater than 70% by weight levels.
Study the effect of adding pva on some physical properties of cmc polymer as ...Alexander Decker
This document studies the effect of adding polyvinyl alcohol (PVA) on various physical properties of carboxymethyl cellulose (CMC) polymer solutions. Several rheological properties (shear viscosity, relative viscosity, specific viscosity, reduced viscosity) and mechanical properties (ultrasonic velocity, absorption coefficient, relaxation time, bulk modulus) of CMC solutions of varying concentrations were measured before and after adding PVA. The results showed that most properties increased with higher CMC concentration but decreased after adding PVA, indicating interactions between the two polymer chains. Specifically, adding PVA enhanced ultrasonic absorption coefficient and reduced viscosity, relaxation time, and compressibility. The study suggests PVA addition can reduce water needs to achieve viscosity goals
Isotherm Modeling and Thermodynamic Study of the Adsorption of Toxic Metal by...CrimsonpublishersEAES
Isotherm Modeling and Thermodynamic Study of the Adsorption of Toxic Metal by the Apricot Stone by Moussa Abbas*, Tounsia Aksil and Mohamed Trari in Environmental Analysis & Ecology Studies
This document presents a method for determining levels of psoralens like psoralen and bergapten in oral solutions of herbal medicines using liquid chromatography. The method involves extracting samples with chloroform, dissolving residues in methanol, and analyzing by HPLC. The method was validated in terms of linearity, accuracy, precision and specificity. Psoralen and bergapten were found to be stable in samples and solutions under various storage conditions. The method provides a fast and reliable means of quantifying psoralen levels in herbal medicines.
TLC Separation of Cephalosporins on Stannic Arsenate LayersIOSR Journals
Abstract: The chromatographic behaviour of some cephalosporins has been studied on synthetic stannic arsenate layers using citrate and borate buffers as mobile phases. Several ternary and quaternary separations have been achieved. The utility of these separations has been demonstrated for estimation of cephalosporins in blood serum from patients.This method used is simple, rapid ,reproducible and can also be applied in the separation and determination of cephalosporins in other biological samples. The limit of detection was found to be 0.20 μg/l.
This document describes a study that developed and optimized an ion-pair reverse-phase high-performance liquid chromatography coupled with inductively coupled plasma mass spectrometry (HPLC-ICP-MS) method for arsenic speciation in Chinese brake fern (Pteris vittata L.). The method was able to separate and detect four arsenic species (arsenite [As(III)], dimethyl arsenic acid (DMA), monomethyl arsenic (MMA), and arsenate [As(V)]) in a single run. This is the first study to show that Chinese brake fern can convert MMA to DMA via methylation. The optimized HPLC-ICP-MS method was then applied to
Equilibrium and kinetic study on chromium (vi) removal from simulatedGJESM Publication
Gooseberry seed powder was investigated as a novel biosorbent for the removal of chromium (VI) from simulated wastewater. Batch experiments were conducted to determine the effects of parameters such as pH, contact time, initial metal concentration, and adsorbent dosage on chromium removal efficiency. Maximum removal of 96% was achieved under optimal conditions at pH 2 within 60 minutes of contact time. Adsorption isotherm and kinetic models were applied to understand the adsorption mechanism, with the data fitting well to the Langmuir isotherm model and pseudo-second order kinetic model. The results indicate that gooseberry seed powder has potential as an effective and economical adsorbent for chromium removal.
Optical resolution trials and a process-concept assessment of the industrial ...Katalin Nemák
This dissertation discusses the synthesis, optical resolution, and scale-up process for producing the pure enantiomers of pipecolo-anilides and pipecolo-xylidides. 13 model compounds were synthesized and all were resolved into their optical isomers. The resolution processes of the N-alkyl-pipecolo-xylidides were investigated in detail. Temperature dependence and recrystallization were studied to produce the enantiomers in high purity. Binary phase diagrams were applied to purification. A new method was developed to select resolving agents and solvents based on chromatographic retention differences. Supramolecular characterization of the diastereomers was also conducted. Finally, a trial production was carried out and plans were
Removal of Harmful Textile Dye Congo Red from Aqueous Solution Using Chitosan...IJERA Editor
Color is an important aspect of human life. Textile industries are the major consumers of dye stuffs. During coloration process, 10 to 15 percent of the dyes will be lost and this will be discharged with the effluents coming from textile industries. These are very difficult to degrade and they may degrade to form products that are highly toxic to human. Today, methods such as coagulation, flocculation, activated carbon adsorption, etc. are available for the removal of dyes. These are all quite expensive and difficult to degrade. Chitosan is a natural hetero polymer derived from chitin. Chitosan has proved to be effective in removing hazardous compounds from environment due to its multiple functional groups. It is available as flakes and powder. In the present work, chitosan beads were prepared and modified with a cationic surfactant CTAB for the removal of dye Congo Red. Batch experiments were conducted to study the effect of CTAB concentration, contact time, agitation speed, adsorbent dosage, initial dye concentration and pH. Batch equilibrium data were analyzed using Langmuir and Freundlich isotherm. Bach kinetic data were analyzed using Pseudo first order kinetic model and pseudo second order kinetic model.
N – methyl thiomethylation and n hydroxymethylation of phthalimideAlexander Decker
This document summarizes a study on the N-methyl thiomethylation and N-hydroxymethylation of phthalimide. Phthalimide was refluxed with DMSO and DMSO-acetic anhydride reagent, yielding two new compounds - N-methyl thiomethyl phthalimide (I) and N-hydroxymethyl phthalimide (II). Spectral data including IR, NMR and mass spectrometry were used to determine the structures of compounds I and II. The reactions and mechanisms for the formation of these compounds from the reactions of phthalimide with DMSO and DMSO-acetic anhydride are discussed.
This document summarizes a study of electron transfer reactions of the eight-coordinate vanadium complex bis-(N-hydroxyiminodiacetate)vanadium(IV) [V(HIDA)2]2–, which is a synthetic analog of the natural compound amavadin found in mushrooms. The self-exchange rate constant of the [V(HIDA)2]2–/– redox couple was determined using both Marcus theory calculations from oxidation/reduction cross reactions, and direct measurement using 51V NMR line broadening techniques. The average self-exchange rate constant was found to be 1.5 × 105 M–1 s–1, similar to that of amavadin itself. This suggests that
Validated HPLC Method for Assay and Content Uniformity Testing of Roflumilast...Ratnakaram Venkata Nadh
Roflumilast is a selective enzyme inhibitor of phosphodiesterase-4. This drug is recommended for treatment of patients suffering from
chronic-obstructive-pulmonary-disease with chronic-bronchitis. Roflumilast is not official in pharmacopoeia and the reported methods
are having high chromatographic run times. A short run time HPLC method was developed for assay and content uniformity testing to
determine the roflumilast in blend and tablets. The mobile phase consists of 10 mM sodium dihydrogen phosphate monohydrate buffer
and acetonitrile in the ratio of 45:55 v/v. The HPLC method was developed using accucore-C18 150 × 4.6 mm, 4 μm column with a flow
rate of 1.0 mL min-1, 215 nm wavelength and 10 μL injection volume with run time of 5 min. The method linearity was proved between
5.02-40.17 μg mL-1 and obtained correlation-coefficient value is 1.0000. The mean recovery of roflumilast was 100.6%. The stability
indicating nature was established and performed the validation by considering ICH Q2 (R1) recommendations.
This document summarizes the synthesis and characterization of lanthanide complexes with the drug cloxacillin. Cloxacillin is an antibiotic drug that is commonly used to treat bacterial infections. Seven lanthanide complexes of the form [Ln(Clox)2(H2O)2]Cl where Ln = La(III), Pr(III), Nd(III), Sm(III), Dy(III), Ho(III) and Er(III) were synthesized. The complexes were characterized using elemental analysis, infrared spectroscopy, electronic spectroscopy, magnetic susceptibility measurements, and thermal analysis. Elemental analysis showed a 1:2 metal to ligand ratio in the complexes. Infrared spectroscopy indicated that cloxacillin binds in
Physico chemical studies on the adsorption of atrazin on locally mined montmo...IAEME Publication
This document discusses the adsorption of the herbicide atrazin onto locally mined montmorillonite clays. Atrazin is widely used but can contaminate water sources through leaching and infiltration. Conventional water treatment methods are ineffective at removing atrazin. The study found that atrazin is quickly adsorbed onto montmorillonite surfaces within 30-40 minutes. The adsorption amount increased with initial atrazin concentration and ionic strength, but decreased with increasing pH and clay mass. Kinetics studies showed the process followed pseudo-first order and intra-particle kinetics models. The Freundlich isotherm model best fit the adsorption, showing a strong affinity between atrazin and
Single-Well Chemical Tracer Tests in Heterogeneous ReservoirsShwan Dizayee
This thesis examines the use of numerical reservoir simulation models to analyze single-well chemical tracer tests in heterogeneous reservoirs. The models implement chemical reactions to simulate tracer behavior and are validated by back-calculating residual oil saturation from simulated tracer responses. When heterogeneities such as different rock regions are introduced, multiple peaks are observed in the tracer response, illustrating delays in arrival times due to irreversible flow. The models can be used to design tracer tests, interpret saturation measurements, and characterize reservoir heterogeneities using well data.
This document summarizes the synthesis of new C-2, C-3 substituted heterocyclic derivatives of L-ascorbic acid and their characterization and evaluation of bacterial activity. Specifically, it describes the multi-step synthesis of Schiff bases and 1,3-oxazepine derivatives from L-ascorbic acid, including protection of hydroxyl groups, esterification, hydrazide formation, Schiff base formation with substituted benzaldehydes, and Diels-Alder reaction with phthalic anhydride to form 1,3-oxazepines. The synthesized compounds were characterized using melting point, FTIR, and 1H NMR spectroscopy and tested for antibacterial activity against gram-positive and
Characterization and Comparative Adsorption Studies of Activated Carbon and S...IRJET Journal
This document presents a study on using rice husk to create activated carbon and silica for removing hexavalent chromium from wastewater. Rice husk is converted to rice husk carbon at 500°C and rice husk ash at 900°C. Batch and column adsorption experiments are conducted to determine the optimal conditions for hexavalent chromium removal. Equilibrium data shows the Freundlich isotherm model fits best. Column studies show increased adsorption at lower flow rates and higher bed depths. Characterization finds rice husk ash contains mostly silica, which is also an effective adsorbent. The rice husk-derived adsorbents show potential for wastewater treatment as low-cost alternatives
This document summarizes research on using eucalyptus bark as a bioadsorbent to remove chromium from tannery effluent. Experiments were conducted using both synthetic effluent and real effluent collected from tanneries. The results showed that eucalyptus bark was effective at removing chromium, with removal rates increasing with lower pH, higher temperature, and longer contact time. Adsorption data fit the Langmuir isotherm model well, indicating eucalyptus bark can successfully remove chromium from tannery wastewater.
This document summarizes research on the effects of gamma irradiation on the viscoelastic properties of sodium alginate polysaccharides. The researchers found that:
1) Irradiating sodium alginate solutions decreased their apparent viscosity and consistency, suggesting the gamma rays broke down the macromolecular structure.
2) Higher irradiation doses and lower polysaccharide concentrations led to greater decreases in viscosity.
3) The non-Newtonian, pseudoplastic behavior of the solutions was maintained after irradiation, though trends moved toward Newtonian behavior at higher doses.
This article describes the development and validation of a simple reverse phase HPLC method for the quantitative analysis of diazepam in pharmaceutical dosage forms. A C18 column with a mobile phase of acetonitrile, methanol and phosphate buffer at a flow rate of 1 mL/min was used to achieve good resolution and retention of diazepam at 6.23 minutes. The method was validated and found to be linear, precise, accurate, sensitive and robust for the analysis of diazepam in tablets with recoveries ranging from 99.4-100.3%.
Separation of calcium carbonate and barium sulphate from a mixed sludge prduc...Timothy Rukuni
South Africa is one of the first countries to implement full-scale mine water reclamation to drinking water quality. Reverse osmosis is already being used on full scale for desalination of mine water. However, with increased recycling of mine water, the result has been the increased generation of sludge. The Council for Scientific and Industrial Research (CSIR) has developed the Alkali-Barium-Carbonate (CSIR-ABC) process that can be used for neutralization and desalination of sulphate-rich effluents while recovering valuable by-products from the mixed sludges produced. A mixture of BaSO4 and CaCO3 sludge is produced as one of the by-products, which preferably needs to be separated into its components prior to thermal treatment. The aim of this study was to separate CaCO3 and BaSO4 from a CaCO3-BaSO4 mixed sludge through dissolution of CaCO3 as Ca(HCO3)2 in contact with CO2. Measured quantities of a simulated CaCO3-BaSO4 mixed sludge from the CSIR-ABC process were fed into a reactor vessel containing deionized water and pressurized CO2 was introduced. The effects of temperature and pressure with time were investigated while monitoring alkalinity, pH and calcium concentration. The findings of this study were: (1) The dissolution rate of CaCO3 was rapid i.e. from 0 to 2000mg/L in the first 20 minutes; (2) Ca(HCO3)2 had a high solubility of about 2 600 mg/L when in contact with CO2 at 1 atm., while BaSO4 was almost completely insoluble; (3) The solubility of Ca(HCO3)2 increased with decreasing temperature and increasing pressure; (4) CaCO3, after conversion to Ca(HCO3)2, was separated from BaSO4 in a CaCO3-BaSO4 mixed sludge; (5) Visual MINTEQ model is a powerful tool that can be used to predict the solubilities of CaCO3 and BaSO4 when contacted with CO2.
Characterization of mining tailings containing sulfides and carbonates applyi...Judson Arantes
Acid mine drainage (AMD) is the process resulting from the oxidation of sulfides exposed to the action of oxygen and water. The characterization of the minerals likely the formation and neutralization of AMD is important for the follow and evaluation of environmental impact. The analysis of X-ray diffraction (XRD) together with the Rietveld method is presented as a promising alternative to favor the identification and quantification of mineral phases. The results of the static test ANC achieved by accounting for carbonates consumed during the test, were correlated with the results obtained by the characterization techniques of X-ray diffraction (XRD) combined with the Rietveld method. The highest concentration of carbonate buffering found in AM2E, which may explain the static test results to be neutralizing for the sample. The major phases identified for both samples were aluminosilicates and quartz, with greater than 70% by weight levels.
Study the effect of adding pva on some physical properties of cmc polymer as ...Alexander Decker
This document studies the effect of adding polyvinyl alcohol (PVA) on various physical properties of carboxymethyl cellulose (CMC) polymer solutions. Several rheological properties (shear viscosity, relative viscosity, specific viscosity, reduced viscosity) and mechanical properties (ultrasonic velocity, absorption coefficient, relaxation time, bulk modulus) of CMC solutions of varying concentrations were measured before and after adding PVA. The results showed that most properties increased with higher CMC concentration but decreased after adding PVA, indicating interactions between the two polymer chains. Specifically, adding PVA enhanced ultrasonic absorption coefficient and reduced viscosity, relaxation time, and compressibility. The study suggests PVA addition can reduce water needs to achieve viscosity goals
Isotherm Modeling and Thermodynamic Study of the Adsorption of Toxic Metal by...CrimsonpublishersEAES
Isotherm Modeling and Thermodynamic Study of the Adsorption of Toxic Metal by the Apricot Stone by Moussa Abbas*, Tounsia Aksil and Mohamed Trari in Environmental Analysis & Ecology Studies
This document presents a method for determining levels of psoralens like psoralen and bergapten in oral solutions of herbal medicines using liquid chromatography. The method involves extracting samples with chloroform, dissolving residues in methanol, and analyzing by HPLC. The method was validated in terms of linearity, accuracy, precision and specificity. Psoralen and bergapten were found to be stable in samples and solutions under various storage conditions. The method provides a fast and reliable means of quantifying psoralen levels in herbal medicines.
TLC Separation of Cephalosporins on Stannic Arsenate LayersIOSR Journals
Abstract: The chromatographic behaviour of some cephalosporins has been studied on synthetic stannic arsenate layers using citrate and borate buffers as mobile phases. Several ternary and quaternary separations have been achieved. The utility of these separations has been demonstrated for estimation of cephalosporins in blood serum from patients.This method used is simple, rapid ,reproducible and can also be applied in the separation and determination of cephalosporins in other biological samples. The limit of detection was found to be 0.20 μg/l.
This document describes a study that developed and optimized an ion-pair reverse-phase high-performance liquid chromatography coupled with inductively coupled plasma mass spectrometry (HPLC-ICP-MS) method for arsenic speciation in Chinese brake fern (Pteris vittata L.). The method was able to separate and detect four arsenic species (arsenite [As(III)], dimethyl arsenic acid (DMA), monomethyl arsenic (MMA), and arsenate [As(V)]) in a single run. This is the first study to show that Chinese brake fern can convert MMA to DMA via methylation. The optimized HPLC-ICP-MS method was then applied to
Equilibrium and kinetic study on chromium (vi) removal from simulatedGJESM Publication
Gooseberry seed powder was investigated as a novel biosorbent for the removal of chromium (VI) from simulated wastewater. Batch experiments were conducted to determine the effects of parameters such as pH, contact time, initial metal concentration, and adsorbent dosage on chromium removal efficiency. Maximum removal of 96% was achieved under optimal conditions at pH 2 within 60 minutes of contact time. Adsorption isotherm and kinetic models were applied to understand the adsorption mechanism, with the data fitting well to the Langmuir isotherm model and pseudo-second order kinetic model. The results indicate that gooseberry seed powder has potential as an effective and economical adsorbent for chromium removal.
Optical resolution trials and a process-concept assessment of the industrial ...Katalin Nemák
This dissertation discusses the synthesis, optical resolution, and scale-up process for producing the pure enantiomers of pipecolo-anilides and pipecolo-xylidides. 13 model compounds were synthesized and all were resolved into their optical isomers. The resolution processes of the N-alkyl-pipecolo-xylidides were investigated in detail. Temperature dependence and recrystallization were studied to produce the enantiomers in high purity. Binary phase diagrams were applied to purification. A new method was developed to select resolving agents and solvents based on chromatographic retention differences. Supramolecular characterization of the diastereomers was also conducted. Finally, a trial production was carried out and plans were
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Color is an important aspect of human life. Textile industries are the major consumers of dye stuffs. During coloration process, 10 to 15 percent of the dyes will be lost and this will be discharged with the effluents coming from textile industries. These are very difficult to degrade and they may degrade to form products that are highly toxic to human. Today, methods such as coagulation, flocculation, activated carbon adsorption, etc. are available for the removal of dyes. These are all quite expensive and difficult to degrade. Chitosan is a natural hetero polymer derived from chitin. Chitosan has proved to be effective in removing hazardous compounds from environment due to its multiple functional groups. It is available as flakes and powder. In the present work, chitosan beads were prepared and modified with a cationic surfactant CTAB for the removal of dye Congo Red. Batch experiments were conducted to study the effect of CTAB concentration, contact time, agitation speed, adsorbent dosage, initial dye concentration and pH. Batch equilibrium data were analyzed using Langmuir and Freundlich isotherm. Bach kinetic data were analyzed using Pseudo first order kinetic model and pseudo second order kinetic model.
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Validated HPLC Method for Assay and Content Uniformity Testing of Roflumilast...Ratnakaram Venkata Nadh
Roflumilast is a selective enzyme inhibitor of phosphodiesterase-4. This drug is recommended for treatment of patients suffering from
chronic-obstructive-pulmonary-disease with chronic-bronchitis. Roflumilast is not official in pharmacopoeia and the reported methods
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Physico chemical studies on the adsorption of atrazin on locally mined montmo...IAEME Publication
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IRJET-Fixed Bed Column Study for Removal of Hexavalent Chromium From Aqueous ...IRJET Journal
Subitha V , Vanathi M " Fixed Bed Column Study for Removal of Hexavalent Chromium From Aqueous Solution by using Denolix Regia Pods (Flamboyant Pods) ",International Research Journal of Engineering and Technology (IRJET), Volume2,issue-01 April 2015.e-ISSN:2395-0056, p-ISSN:2395-0072. www.irjet.net .published by Fast Track Publications
Abstract
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Heavy Metals in Sediment from Alvarado Lagoon System in Veracruz, MéxicoIJEAB
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IJRET : International Journal of Research in Engineering and Technology is an international peer reviewed, online journal published by eSAT Publishing House for the enhancement of research in various disciplines of Engineering and Technology. The aim and scope of the journal is to provide an academic medium and an important reference for the advancement and dissemination of research results that support high-level learning, teaching and research in the fields of Engineering and Technology. We bring together Scientists, Academician, Field Engineers, Scholars and Students of related fields of Engineering and Technology
The document summarizes research on using functionalized multi-walled carbon nanotubes (MWCNTs) to remove chromium (Cr3+) ions from wastewater through adsorption. The researchers found that MWCNTs achieved 99.83% removal of Cr3+ ions at an optimum dosage of 25 mg in a pH 6 solution. Equilibrium adsorption experiments showed that the Langmuir isotherm model fit the data better than the Freundlich model, indicating monolayer adsorption of Cr3+ ions onto the MWCNT surfaces. Fourier transform infrared spectroscopy characterization confirmed the presence of functional groups like carboxyl that contribute to the adsorption of Cr3+ ions.
The document summarizes experiments conducted to optimize a composite adsorbent for treating Desa Bakti River water using crushed cockle shells, natural zeolite, and coal fly ash. Jar tests showed the maximum COD reduction occurred on day 3 with 3g/L of each adsorbent. Equilibrium adsorption capacity was highest for crushed cockle shells. FTIR analysis indicated adsorption of phosphates and organic matter onto the adsorbents. Optimization using D-optimal design found the best ratio was 0.25:0.75 crushed cockle shells to natural zeolite. Column tests achieved over 90% removal of BOD, COD, TP and TN. Isotherm analysis showed
IJERA (International journal of Engineering Research and Applications) is International online, ... peer reviewed journal. For more detail or submit your article, please visit www.ijera.com
2022 - Removal of Cr(VI) from solution using UiO-66-NH2 prepared in a green w...DrChimie
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This study aims to employ low-cost agro waste
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than 96.9% removal of Chromium was achieved using crude
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monolayer adsorption capacity of 40 mg/g and a separation
factor of 0.0416 indicating it as best adsorbent among the three
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kinetics with pseudo first order and pseudo second order
reactions. Pseudo second order kinetics model fits well to the
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This document summarizes research on a novel nanoporous sorbent material for removing mercury from coal plant wastewater. The material uses a mesoporous silica substrate functionalized with self-assembled thiol monolayers. Laboratory experiments showed the material could adsorb over 98% of mercury from simulated coal plant effluent, with an maximum adsorption capacity of 625 mg Hg per gram. Mercury adsorption was not significantly impacted by pH, ionic strength, or presence of other metals. The thiol-functionalized sorbent selectively binds mercury through soft acid-base interactions between mercury and thiol groups.
This document describes a study that prepared chitosan from waste prawn shells and evaluated its performance as an adsorbent for Remazol Red dye. Chitosan was characterized using various analytical tools and showed good thermal stability. Batch experiments were conducted to determine the effects of pH, contact time, and initial dye concentration on adsorption capacity. Maximum adsorption of 313.4 mg/g occurred at pH 3.0 after 30 minutes. Experimental data fit the Langmuir isotherm model and followed pseudo-second order kinetics. The study demonstrated that chitosan can be effectively used as a low-cost adsorbent for Remazol Red dye removal from wastewater.
This document summarizes a study on using activated carbon prepared from coconut shells to remove hexavalent chromium (CrVI) from electroplating industry wastewater. Activated carbon was prepared at different temperatures and activation times and characterized. Batch adsorption experiments were conducted to determine the effect of parameters like adsorbent dosage, pH, contact time, and initial chromium concentration on chromium removal. The activated carbon was found to effectively remove hexavalent chromium from solution, with removal increasing with longer contact times and higher adsorbent dosages. This shows promise for using activated carbon from coconut shells to treat electroplating wastewater contaminated with toxic hexavalent chromium.
Effective Adsorption of Cadmium (II) Ion on Orange Peels (Citrus Sinensis)IRJET Journal
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(THPS BIOCIDE BASE ) moniotoring in sea waterAlsayed Yakoot
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Similar to Mathematical model of raw hide curing with brine (20)
Properties of biopolymers produced by transglutaminase treatment of wpi and g...Eduard Hernàndez I PMP®
Byproduct utilization is an important consideration in the development of sustainable processes. Whey
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The document evaluates degreasers and a glycolipid surfactant as additives to brine curing of hides. It finds:
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The upgrading of leather that presents loose areas
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Biocarb Ox combines a premium quality wood-based activated carbon in conjunction with a proprietary blend of catalytically active inorganic phases, which leads to an extraordinarily high H2S breakthrough capacity (80 kg H2S/100 kg media). Unlike other medias, Biocarb Ox does not convert H2S to sulphuric acid (H2SO4), which may lead to equipment corrosion problems and creates disposal issues. Conversely, H2S is catalytically oxidized to sulphur (S) in the active sites on metal oxides. Next, sulphur migrates and builds up in the micropores of the activated carbon phase. Consequently, the metal oxides are available again to oxidize new H2S molecules.
The document is the doctoral thesis of Eduard Hernández Balada directed by Dr. José Costa López and Dr. Jaume Cot Cosp. The thesis examines improving conventional leather making processes to reduce environmental impact. It was completed as part of a doctoral program in Environmental and Product Engineering from 2006-2008 at the University of Barcelona. The thesis analyzes preservation of raw hides and skins with brine curing and explores potential natural fillers like whey and gelatin for use in the leather industry. The goal is to make leather processing more environmentally sustainable.
The document discusses using whey protein isolate (WPI) and gelatin as potential fillers for leather. It assessed their effectiveness on upholstery and shoe upper leather. Pretreating the leather with microbial transglutaminase (mTGase) increased protein uptake for upholstery leather but decreased it for shoe upper leather. For shoe upper leather, mTGase pretreatment followed by 5% WPI and 0.5% gelatin dramatically improved grain break. The fillers improved color and other properties for both types of leather. WPI and gelatin show potential as renewable and less expensive alternatives to traditional petroleum-based fillers.
The document discusses research conducted at the USDA to develop more sustainable and efficient processes for leather making. It aims to reduce the environmental impact of conventional leather production. The research includes developing new techniques for hide preparation, drying, and finishing, as well as nondestructive testing to improve leather quality and durability. Additional funding was obtained to investigate more efficient short-term hide preservation methods like brine curing.
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Mathematical model of raw hide curing with brine
1. 167
MATHEMATICAL MODEL OF RAW HIDE CURING WITH BRINE
by
EDUARD HERNANDEZ BALADA l2, WILLIAM N. MAluviERl*, KAREL KOLOMAZNIK3, PETER H. Coo 1 AND ROBERT L. DUDLEY'
' U.S. Department ofAgriculture, Agricultural Research Service, Eastern Regional Research Center
600 EAST MERMAID LANE, WYNDMOOR, PA 19038 USA
'Department of Chemical Engineering, University of Barcelona
MARTI I FRANQUS 1, 08028 BARCELONA, SPAIN
3 Tomas Bata University
MOSTNI 5139, 760 01 ZLIN, CZECH REPUBLIC
ABSTRACT impacto medioambiental asociado con la descarga de
grandes cantidades de electrolitos en la operación de
The most common method of preserving raw hides remojo. Nuestro objetivo a largo plazo es resolver los
is brine curing with sodium chloride. However, this mencionados problemas. Inicialmente, estudiamos la
process has three important disadvantages: first, the absorción de sal y su mecanismo de difusión a fin de
length of time that it takes, which is a minimum of reducir el tiempo de curado. Un modelo matemático
18 hours; second, the insufficient degree of curing de reacción continua de un sistema unidimensional
reached in some hides due to an overload and cerrado fue escogido Para describir la difusión de
possibly the low efficiency of the brine raceway; and cloruro de sodio en la pie1 durante el proceso de
finally, the environmental impact associated with curado a fin de buscar las óptimas condiciones de
the discharge of large quantities of electrolytes in the curado, tales como la concentración optima de
soaking step. Our long term goal is to address all salmuera y el porcentaje óptimo de baflo. El efecto
three issues. Initially, we have carried out a study de estos dos parámetros en los valores del coeficiente
of the salt uptake and its diffusion mechanism in de transporte 2 son presentados. La difusión de sal en
order to attempt a reduction in the curing time. A la pie] fue monitorizada mediante la determinaciOn
continuous reaction mathematical model of a closed de concentración de cloruros en la solución residual
one dimensional system that describes the diffusion de salmuera. Además, una muestra de piel fue
of sodium chloride in the hide during the curing curada con una solución de salmuera etiquetada
process was chosen in the search for the optimum con una sustancia fluorescente y analizada mediante
brine curing conditions such as the optimum brine microscopla epifluorescente Para la visualización
concentration and percent float. The effect of these directa del sodio en la pie1.
two parameters on the values of transport coefficient
was reported. Brine diffusion into the hide was INTRODUCTION
tracked by measurement of the chloride concentration
of the residual brine solution. In addition, a piece of Raw hides and skins are - 60-70% water and - 25-30%
hide was cured with a fluorescently labeled brine protein. In this form the hide is susceptible to bacterial
solution and analyzed by means of epifluorescent activity within hours after being removed from the carcass.
microscopy for direct visualization of the sodium The autolytic degradation of skins/hides is assumed to be due
location within the hide. to a combined action of tissue enzymes and bacteria, the latter
requiring moisture to be viable.' Curing is the process that
RESUMEN provides an environment in which bacteria cannot survive.
Several curing agents have been reported in the literature, e.g.,
El método más comi.'in para preservar pieles crudas potassium chloride , 2 silica gel,'-' boric acid,' and herbal-based
es el curado con salmuera. Sin embargo, este products .6 Common salt, in spite of its inherent impact on
proceso presenta tres desventajas: en primer lugar, the environment and the large amount required, is the most
el tiempo que requiere, un mIriimo de 18 horas; popular and inexpensive material used to preserve hides and
en segundo lugar, el insuficiente nivel de curado skins. A suitable improved method would yield savings in salt,
alcanzado en algunas pieles debido a la sobrecarga y shipping and effluent treatment costs as well as a diminished
baja eficiencia del tanque de curado; y finalmente, el environmental impact. Mathematical modeling has been
* Corresponding Author - Email address: william.marmer@ars.usda.gov
Mention of trade names or commercial products in this article is solely for the purpose of providing specific information
and does not imply recommendation or endorsement by the U.S. Department of Agriculture.
Manuscript received November 14, 2007, and accepted for publication November 19, 2007
JALCA, VOL. 103, 2008
2. 168 MODEL OF RAW HIDE CURING
c(hr)=r'c0(r)
V
c,(r)
(O,rj=O
k) L'1
I/I
j
flesh side OA
b
(1 >1'
Figure 1: Mathematical model of the curing process of a raw hide.
Figure 2: Dimensionless sodium chloride concentration field within the
reported to be a powerful tool in the optimization of processes hide during the curing process.
such as soaking of salted cattle hides. 7 ' 8 Curing has been
modeled in substrates such as cheese" () and meat", but has not
been studied for the particular case of raw hides.
(2)
The aim of this work is to develop and verify a mathematical ax dx
model that describes the diffusion of sodium chloride in the c(x,O) = 0 (2a)
hide during the curing process. Upon its verification, the
model is applied in the search of the optimum values of process c0(0)=c01, (2b)
variables such as brine concentration, float percentage and
curing time. Equation (3) is valid under an ideal mass transfer from the bulk
solution to the surface of the solid phase.
THEORY
We propose a continuous reaction model to describe the c(b,x) = £ c, (r)
(3)
diffusion of sodium chloride from the bath containing brine
solution to the surface of the solid phase (hide). The model The introduction of dimensionless parameters (equations 4a
assumes that salt will further diffuse into the hide's inner to 4e) has been demonstrated to be a useful tool in the model
volume where it will form a non-stationary concentration development.
field (Figure 1). It also assumes that diffusion takes place only
into the flesh side and that hide parameters such as thickness,
surface and properties of both hair and flesh sides will remain C (4a)
= LC0p
constant throughout the whole process.
CID
Curing can be considered as a counter diffusion in which C,
(4b)
sodium chloride soaks into the skin as water simultaneously op
washes out. Equation (1) describes a non-stationary one
dimensional concentration field inside the inner volume of the X =' (4c)
solid phase, defined by Fick's second law. Boundary condition
(la) assumes that sodium chloride diffuses into the hide from
D x
the flesh side only. Terms are defined at the end of the paper. F
0 =--- (4d)
ac
D.---(x,r) O<x'<b 'r>O Na=J2- (4e)
The dimensionless time, also called Fourier's number [F0],
(la) assesses the proximity of the process to the equilibrium, i.e.
Ox
equilibrium is reached when F 0 --- . The dimensionless
Equation (2) corresponds to a mass balance of a closed system soaking number [Na] expresses the ratio between the volumes of
in which salt flow at the hide surface is equal to accumulation liquid and solid phases. The replacement of the dimensionless
speed of sodium chloride in the bath. Equations (2a) and parameters into the previous model leads to a new dimensionless
(2b) are the initial boundary conditions (t = 0). They assume model (Eq. (5a) to (50).
a null initial content of sodium chloride in the fresh hide
and a constant initial value of brine concentration in the
bath respectively.
JALCA. VOL. 103, 2008
3. MODEL OF RAW HIDE CURING 169
F0g
- Na
a e
N.
C(F) -2Na2
N 20-
N10-.--<
+Na
(9)
Figure 3 shows the curves of the integral average concentration
for various values of soaking number.
C)
Determination of Diffusion Coefficients
The value of effective diffusion coefficient of sodium chloride
in the hide can be evaluated from experimental data. Crank"
suggested an equation for the diffusion coefficients study at
short times:
= 1+Na ,j -
02 04 08 08 1 12 14 18 18
I CO P c0(t)
Figure 3: Dimensional sodium chloride concentration field within the
c0 , -c 0 (cc) Na
hide during the curing process.for various soaking numbers. (10)
From the mass balance
O<X<l F. >0
V0 = C12 V + E CO. V
(11)
(5b) We get
Q1, F,) = C O (FO) COPNa
CO =
Na+ c (12)
(50
ax aFO Transport parameter ? is defined as a ratio of the effective
diffusion coefficient D' to pore half length (a) square.
(0,F)=O
0
ax (5d)
C(X,O) = 0
(5e) A D -- 13)
- D'
-
a2 (
C'(0) = 1 (50
when the factor for the tortuosity of the pores:
the analytical solution of which can be obtained by means of
(14)
Laplace's transformation:
cos(Xg,)eT-o g"
c(x F Na +2Na ?. is an important value from an engineering point of view since
e+Na esin(g )
E cos(g,,)- -g Na'sin(g) it includes two phenomena not considered in the presented
91,
model, which are the transport of water from the hide to the
(6)
bath and the interaction between sodium chloride and water
Where g0 are the roots of the transcendent equation (7).
counter flows during the curing.
Nag
tg(g) = - ( g0 > 0) (7)
EXPERIMENTAL
E
The three dimensional concentration field graphic Materials
corresponding to Eq. (6) is shown in Figure 2. Fresh cow hides were purchased from a local abattoir. They
were soaked for 2 h (with surfactant) and then fleshed.
Replacing Eq. (7) into Eq. (6) and rearranging terms (for X = 1), Approximately 6 x 10 in (15 x 25 cm) pieces were cut and
we obtain an equation that illustrates the variation of brine stored at -20°C. They were thawed at 4°C just before use.
concentration with time. Food grade sodium chloride of purity minimum 99.82% was
obtained from US Salt Corporation (Watkins Glen, NY). All
-F0 -g
other chemicals were reagent grade and used as received.
°'- Na +2Na
c0( F
Na Nag
's+Na+ (8) Methods
Thawed hide was cut into square pieces of approximately 4 x
In addition, integration of Eq. (6) leads to Eq. (9) which 4 in (10 x 10 cm) with an average weight of .- 100 g. They
calculates the optimal time in order to reach a certain were transferred to a Dose drum (Model PFI 300-34, Dose
Maschinenbau GmbH, Lichtenau, Germany), and tumbled at
content of sodium chloride in the skin, C (integral average
concentration).
JALCA, VOL. 103, 2008
4. 170 MODEL OF RAW HIDE CURING
and 5pM of the fluorescent dye and gently agitated. A 2-3 mm
wide slice of the sample was excised manually with a stainless
steel razor blade (cutting from flesh surface toward the grain) at
regular intervals of incubation time, then mounted onto Petri
dishes for imaging, using a Leica MZ FUJI stereomicroscope
(Leica Microsystems, Bannockburn, IL, USA) equipped for
epifluorescence and with a model DC200 color charge couple
device camera system at 2.5x magnification. Samples were
- FIesI irradiated with blue (470/40 nm) and UV (360/40 nm) light,
4h 5h 24h 48h
and images of the fluorescence were acquired at 0.1 (blue)
Figure 4: Epifluorescent microscopic images of a cross section of a hide at and 0.44 (UV) seconds of exposure time. Control samples,
different stages of curing. The hide was cured with 30% (w/v) immersed in 500% v/v nano-pure water and 5pM dye, were
labeled sodium chloride solution. examined under the same conditions of concentration and time
to assess the penetration of the fluorescent dye in the absence of
salt, and a blank sample was also examined to evaluate possible
autofluorescence of the untreated raw hide.
0.70
0.60 RESULTS AND DISCUSSION
0.50
Results and Discussion Epifluorescence Microscopy
0.40
The diffusion of labeled sodium ions into the cross section
0.30
of hide samples was followed by means of epi-fluorescent
0.20 microscopy. In Figure 4, increased fluorescence indicating
0.10 diffusion of salt started on the flesh side and gradually moved
0.00 toward the hair side. The lack of fluorescence development at
10 12 the hair side validated the mathematical assumption described
4 4rniuf) by Eq. (la); this can be attributed to the existence of a thin
protective barrier of sebaceous oil.i4 The series of images
Figure 5: Determination of transport parameter X from experimental demonstrate the advance of fluorescence due to sodium
data. The graph corresponds to cOp = 30% (wlv) and Na = 3. ions into the cross sections of hide as well as increases
in fluorescence intensity throughout curing time. Signal
saturation in the area near the flesh side, denoted by a very
6 rpm with brine solution for varying time intervals after which bright fluorescence, was observed after 5 h of curing. The
they were pulled out of the drum, hand-squeezed to wipe excess apparent retrograde movement of the labeled sodium between
water, sealed in plastic bags and placed in the refrigerator. A 2 h and 5 h may be due to the shrinking of the hide caused by
fraction of the residual brine solution was also collected at dehydration. Surprisingly, sodium ions did not seem to reach
different time intervals. Two sets of experiments were carried the hair side even after 48 h of curing. This could be due to
out: a constant 300% (v!v) float (volume of brine solution/ many factors. In order to determine if the penetrability of
volume of hide) at different initial salt concentration levels the dye is a technical factor, a sample of hide incubated in an
(20%, 25%, 30% and 35% (wlv), which correspond to 64, aqueous solution of dye for 24 hours was examined under the
80, 96 and 100°SAL, respectively) and a constant 30% (wlv) microscope and then transferred to a beaker with concentrated
initial salt concentration (weight of NaCl/volume of solution) brine solution for 24 more hours. The dye did not fluoresce in
at different float percentages (300%, 500%, 750% and 1000% the uncured sample but showed a high fluorescence after being
v/v). Density of hide was assumed to be - lg/cm3. cured for 24 hours (graphs not shown). However, fluorescence
was absent or undetectable in the upper part of the corium,
Analyses leading to the possibility that the dye may not penetrate into
Chloride concentration determination the tightly-woven and dense structure of the corium, possibly
Chloride concentration was determined by classical Mohr due to its size (MW = 586 Da). The use of scanning electron
titration.' 3 Residual brine samples were diluted (1:100 v/v) microscopy with energy dispersive X-Ray spectroscopy (SEM-
in nano pure water prior to titration. All samples were run EDS) and elemental mapping to measure the amount and
in triplicate. location of salt in a brine-cured hide is an alternative method
to fluorescence imaging and this approach is planned.
Fluorescence Imaging
CoroNa TM Green Sodium Indicator fluorescent dye (Invitrogen, Determination of Diffusion Coefficients
Carlsbad, CA) was used as a probe of sodium ions diffusing The diffusion of salt in the hide was evaluated by means of the
into raw hide from brine solution. A piece of raw hide of transport coefficient X, which can be calculated from the slope
approximately 1 x 1 in (2.5 x 2.5 cm) was immersed in a of the straight line that results from plotting C 0(t) versus square
beaker containing 500% v/v float of a 30% w/v NaCl solution root of time (Eq. 10). Taking into account early published
JALCA, VOL. 103, 2008
5. MODEL OF RAW HIDE CURING 171
TABLE I
Transport Coefficient ? for Various Conditions of Initial Brine Concentration
(c0 ) and Soaking Number (Na)
Na=3 Cop
=30%(wlv)
(% w/v) k iO (s') R2 Na ? 10 (s') R2
20 4.2 0.835 5.3 0.949
25 3.8 0.921 9.0 0.887
30 5.3 0.949 7.5 4.1 0.905
35 10.7 0.776' 10 8.6 0.876
a2 < critical value for a = 0.05.
results 12 and the accuracy of our measurements, the linear common practice in tanneries, which operate at Na 4 even
dependence holds approximately as far as to the value of C0(t) though the generally accepted rule requires a Na ^- 5 in order
= 0.6. Figure 5 depicts this correlation for the particular case for hides to receive a proper cure) 8 In addition, a large float
of c11 = 30% (w/v) and Na = 3. will help maintain an almost constant salt concentration. The
outstandingly low value of? obtained for Na = 7.5 may be due
As seen in Table 1, all X values, except from that of c0=35% to factors inherent to the hide, e.g., poor fleshing, which slows
(wlv), are on the order of 10 s. These results are of the same down salt penetration, agglutination of the fibers and content
order of magnitude as those reported in the mathematical of dry matter.
model of soaking 15, which suggests that the diffusion of salt
does not significantly differ between curing and soaking. A Determination of Optimum Brine Curing Conditions
numerical value of ?. for c11 =35% (wlv) may not be reliable, An 85% salt saturation of the water remaining in the hide was
because the brine was initially supersaturated and the model established as a minimum standard in order to attain a proper
was developed for homogeneous solutions solely. Note than degree of cure. 19 One can calculate the theoretical minimum
a saturated brine solution holds 31.7g of salt in 100 ml of soaking number needed to attain this saturation percentage in
solution, (c0 ) at 25°C.16 the equilibrium, that is, at infinite time, and without further
additions of salt into the solution. From Eq. (8), If T — then
A comparison of the individual values of X is not simple, since F - ; thus the second summand can be neglected, giving:
they may be affected by some of the following factors: 1. The
thickness of the hide, which may vary throughout the process c Na
o
C
and exerts a strong effect on the value of?, as seen in Eq. (13).
Coll
s+Na (15)
2. The pore length, which varies among the hides and is hardly
measurable. 3. The dry matter content of the hide, the variation Replacing C = E Co and rearranging for Na,
of which may extensively modify ?.. In fact, ? may drop up
to two orders of magnitude between a wet and a dry hide. 15,17 C
Na =
4. The temperature, which affects the diffusion rate and was C I C op -c (16)
sometimes difficult to keep at 25°C during the process. 5. The
influence of the error in the measurement, i.e. the difficulty Using C = 0.85 • C c o ,,, a porosity of E = 0.5 and co, = 30 %
to measure a small chloride concentration diminution with (wlv), and assuming that all pores are filled up with brine
the Mohr method despite the very low coefficient of variation solution, a soaking number of 4.4 is needed to reach 85%
(CV) found for this technique (< 1%). saturation. Solving Eq. (16) for Co. = 20 and 25% (wlv),
negative values of Na are obtained, indicating the unfeasibility
Even so, one can draw the conclusion on the effect that both c0
to attain 85% saturation. On the other hand, the minimum
and Na exert on the values of?.. Increasing values of c 0p yielded
soaking number would drop to 2.8 if the cure was started
larger values of ?. as a consequence of an increasing gradient
concentration between the solid phase and the solution, which out with a saturated brine solution (31.7 % (wlv), or
is in accordance with Fick's second law of diffusion. This fact 100 'SAL). Notice that these values depend on the porosity of
corroborates a general practice applied in curing raceways, the hide, which varies from one to another and within itself.21
where solid salt is periodically added to the brine solution to Therefore, slightly different values of minimum Na's would be
keep it close to saturation (a 97 'SAL). The float percentage obtained using another value of porosity.
also exerts a remarkable effect on the values of transport
parameter 7. Larger floats yielded faster diffusion of salt Working out the value of c0 from Eq. (16) and using
into the hide, even though that effect became less significant Na = 3, we received a minimum initial brine concentration
for Na > 5. That experimental observation corroborates the of 30.8% (wlv) in order to achieve the target saturation level.
JALCA, VOL. 103, 2008
6. 172 MODEL OF RAW HIDE CURING
By means of Eq. (9), the plot of which is depicted in Figure DEFINITION OF TERMS
3, one is able to calculate the curing time needed to reach an
85% salt saturation in the hide. As just mentioned above, c: concentration of sodium chloride in the hide moisture, at a
this level cannot be achieved for c0 = 20, 25 and 30% (wlv) distance x from the boundary (t > 0) [mol m3]
and Na = 3. However, a time of 4.2 h is obtained for a 35% c o : concentration of sodium chloride in the bath (t > 0) [mol
(w/v) supersaturated brine and Na = 3. The 85% saturation is m]
Con: concentration of saturated sodium chloride solution at
also achieved in 4.9, 7.7 and 3.4 h if the hide is cured with a
25°C [mol m]
brine of c0 = 30% (w/v) and Na = 5, 7.5 and 10, respectively.
cop: initial concentration of sodium chloride in the bath (t =
These values are substantially lower than the 18 hours that
0) [mol m3]
usually are required for a full cure in a normal float (Na-5).
c. equilibrium concentration of sodium chloride in the bath
The calculations of those times contain the parameter ?., - [mol m3]
and therefore are affected by the same factors mentioned in C : dimensionless concentration integral average [1]
the previous section. In spite of this, it is interesting to note D: diffusion coefficient of sodium chloride in the hide [m 2 s1]
the decrease of curing time with increasing float percentages, D': effective diffusion coefficient of sodium chloride in the
except from the erratic value obtained for Na = 7.5. hide [m 2 s1]
S: outer surface of the solid phase (skin) [m2]
CONCLUSIONS a: pore half length of the skin [m]
b: thickness of cured hide [m]
Over 20 millions brine-cured hides were exported by the U.S. Na: soaking number [1]
in 2006 (U.S. Leather Industry Statistics, 2007). Increasing V: volume of skin [m3]
commodity prices for sodium chloride over the past few years V0: volume of brine solution [m3]
together with issues associated with water pollution set the F0: Fourier number/dimensionless time [1]
alarm off in the leather and meatpacking industries. The X: dimensionless distance [1]
purpose of research reported in this article was to optimize the
C, C o : dimensionless concentrations [1]
brine curing of hides and skins under specific process conditions
Greek symbols
by means of mathematical modeling. The diffusion of salt into
T: time (s)
the hide was characterized by the transport coefficient X, which
C: porosity of solid state [1]
was found to be in the order of 10 s'. The usage of saturated
X: transport coefficient [s]
brine as well as large floats (>500%) yielded higher values of
?., therefore higher diffusion rates. From the model it was
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