This document summarizes a study on the inhibition of copper corrosion in nitric acid solution by 3-arylazo 1,2,4-triazole compounds (AT). The main points are:
1) Potentiodynamic polarization and Tafel methods showed that AT compounds are good inhibitors of copper corrosion in nitric acid, achieving over 95% inhibition efficiency at 10-4M concentration.
2) The high inhibition is believed to be due to adsorption of the AT compounds or formed Cu(II)-AT complexes at the electrode interface.
3) Cathodic polarization measurements indicated AT dyes are predominantly cationic inhibitors that act in the cathodic region.
This study investigated the inhibition of copper corrosion in nitric acid solution by 3-arylazotriazole compounds (AT). Potentiodynamic polarization and Tafel methods showed that AT compounds were good inhibitors. The inhibition effect is likely due to adsorption of AT molecules and formation of Cu(II)-AT complexes on the electrode surface. Higher AT concentrations achieved over 95% inhibition efficiency. Temperature increased corrosion rates by enhancing desorption and surface reactions. UV-Vis spectroscopy and cyclic voltammetry supported the formation of Cu(II)-AT complexes in solution.
The document summarizes research on the inhibition effect of various hydantoin compounds on the corrosion of iron in nitric and sulfuric acid solutions. Key findings include:
1) Hydantoin compounds were found to be mixed-type inhibitors that reduce the corrosion rate of iron in both acids. Inhibition efficiency increased with compound concentration and followed the Temkin adsorption isotherm.
2) Polarization curves showed hydantoin compounds adsorb to the metal surface. Higher inhibition occurred with compounds having more adsorption sites like the carbethoxy group.
3) Corrosion rates increased with temperature in both the presence and absence of inhibitors. Activation energy was higher when inhibition efficiency was greater, suggesting
This summary provides the key details from the document in 3 sentences:
The document reports on a study of chromium-catalyzed ethylene oligomerization using bis(benzimidazolemethyl)amine (BIMA) ligands. It finds that N-alkyl-substituted BIMA ligands produce extremely high catalyst activities (>100,000 g mmol-1 h-1 bar-1) and yield alternating distributions of linear α-olefins. The alternating distributions can be explained by a metallacyclic mechanism in which both single and double ethylene insertions into the metallacycle are possible.
2009_Nguyen et al._Journal of Organometallic ChemistryHuyen Lyckeskog
The document describes the preparation and characterization of new dinuclear half-titanocene complexes with ortho- and meta-xylene linkages for use as catalysts in styrene polymerization. Specifically, it details the synthesis of four dinuclear complexes containing either ortho- or meta-xylene bridges and either chloride or aryloxo ligands on the titanium centers. The catalysts were characterized and found to be effective for producing syndiotactic polystyrene when combined with methylaluminoxane. Testing revealed that activity increased with meta-xylene bridges and aryloxo ligands compared to ortho-xylene bridges and chloride ligands, respectively. The activity was also influenced by temperature, aluminum-to
This study investigates the corrosion inhibition of iron by six mono-azo dye derivatives (MAD_1-6) in 2M HNO3 and 2M NaOH solutions using experimental and computational methods. Gravimetric, thermometric, UV-Vis spectrophotometric, and electrochemical polarization techniques were used to determine inhibition efficiencies experimentally. Density functional theory calculations and molecular dynamics simulations were performed to calculate quantum chemical parameters and binding energies on the Fe(110) surface. Theoretical data agreed well with experimental inhibition efficiencies, with MAD_1 and MAD_6 showing the best inhibition in acidic and alkaline solutions, respectively.
The document describes the process for extracting rare-earth elements from monazite ore. Monazite ore contains rare-earth metal oxides, phosphates, thorium, and uranium. The process involves grinding the ore, digesting it with sulfuric acid to dissolve the rare-earth elements, filtering and precipitating thorium phosphate, rare-earth hydroxides, and uranium concentrate. An older process used acid cracking with sulfuric acid at high temperatures, which generated waste and lost the phosphate content. The modern process allows recovery of the valuable phosphate.
Formal potential analytical technique, P K MANIP.K. Mani
This document discusses formal potentials and their importance in redox titrations. It begins by explaining that standard potentials (E°) assume ideal conditions that are rarely present in practice. Formal potentials (E°') account for non-ideal conditions like varying activities of species. The document then provides examples of how complex formation in solutions can affect formal potentials compared to standard potentials. It discusses various redox indicators used in titrations and criteria for their selection, including their formal potentials relative to the analyte. In summary, the document outlines the concept of formal potentials, why they are more practical than standard potentials, and considerations for choosing redox indicators in titration analyses.
The document discusses redox titrations, which are volumetric methods of analysis that rely on the oxidation or reduction of an analyte using redox indicators or potentiometry. It covers changes in solution potential during titration, basic calculations, sample preparation methods, common titrants, and examples of determining the equivalence point potential in redox reactions. The document also provides details on potentiometric titration and using a platinum electrode to monitor the potential during titration instead of an indicator.
This study investigated the inhibition of copper corrosion in nitric acid solution by 3-arylazotriazole compounds (AT). Potentiodynamic polarization and Tafel methods showed that AT compounds were good inhibitors. The inhibition effect is likely due to adsorption of AT molecules and formation of Cu(II)-AT complexes on the electrode surface. Higher AT concentrations achieved over 95% inhibition efficiency. Temperature increased corrosion rates by enhancing desorption and surface reactions. UV-Vis spectroscopy and cyclic voltammetry supported the formation of Cu(II)-AT complexes in solution.
The document summarizes research on the inhibition effect of various hydantoin compounds on the corrosion of iron in nitric and sulfuric acid solutions. Key findings include:
1) Hydantoin compounds were found to be mixed-type inhibitors that reduce the corrosion rate of iron in both acids. Inhibition efficiency increased with compound concentration and followed the Temkin adsorption isotherm.
2) Polarization curves showed hydantoin compounds adsorb to the metal surface. Higher inhibition occurred with compounds having more adsorption sites like the carbethoxy group.
3) Corrosion rates increased with temperature in both the presence and absence of inhibitors. Activation energy was higher when inhibition efficiency was greater, suggesting
This summary provides the key details from the document in 3 sentences:
The document reports on a study of chromium-catalyzed ethylene oligomerization using bis(benzimidazolemethyl)amine (BIMA) ligands. It finds that N-alkyl-substituted BIMA ligands produce extremely high catalyst activities (>100,000 g mmol-1 h-1 bar-1) and yield alternating distributions of linear α-olefins. The alternating distributions can be explained by a metallacyclic mechanism in which both single and double ethylene insertions into the metallacycle are possible.
2009_Nguyen et al._Journal of Organometallic ChemistryHuyen Lyckeskog
The document describes the preparation and characterization of new dinuclear half-titanocene complexes with ortho- and meta-xylene linkages for use as catalysts in styrene polymerization. Specifically, it details the synthesis of four dinuclear complexes containing either ortho- or meta-xylene bridges and either chloride or aryloxo ligands on the titanium centers. The catalysts were characterized and found to be effective for producing syndiotactic polystyrene when combined with methylaluminoxane. Testing revealed that activity increased with meta-xylene bridges and aryloxo ligands compared to ortho-xylene bridges and chloride ligands, respectively. The activity was also influenced by temperature, aluminum-to
This study investigates the corrosion inhibition of iron by six mono-azo dye derivatives (MAD_1-6) in 2M HNO3 and 2M NaOH solutions using experimental and computational methods. Gravimetric, thermometric, UV-Vis spectrophotometric, and electrochemical polarization techniques were used to determine inhibition efficiencies experimentally. Density functional theory calculations and molecular dynamics simulations were performed to calculate quantum chemical parameters and binding energies on the Fe(110) surface. Theoretical data agreed well with experimental inhibition efficiencies, with MAD_1 and MAD_6 showing the best inhibition in acidic and alkaline solutions, respectively.
The document describes the process for extracting rare-earth elements from monazite ore. Monazite ore contains rare-earth metal oxides, phosphates, thorium, and uranium. The process involves grinding the ore, digesting it with sulfuric acid to dissolve the rare-earth elements, filtering and precipitating thorium phosphate, rare-earth hydroxides, and uranium concentrate. An older process used acid cracking with sulfuric acid at high temperatures, which generated waste and lost the phosphate content. The modern process allows recovery of the valuable phosphate.
Formal potential analytical technique, P K MANIP.K. Mani
This document discusses formal potentials and their importance in redox titrations. It begins by explaining that standard potentials (E°) assume ideal conditions that are rarely present in practice. Formal potentials (E°') account for non-ideal conditions like varying activities of species. The document then provides examples of how complex formation in solutions can affect formal potentials compared to standard potentials. It discusses various redox indicators used in titrations and criteria for their selection, including their formal potentials relative to the analyte. In summary, the document outlines the concept of formal potentials, why they are more practical than standard potentials, and considerations for choosing redox indicators in titration analyses.
The document discusses redox titrations, which are volumetric methods of analysis that rely on the oxidation or reduction of an analyte using redox indicators or potentiometry. It covers changes in solution potential during titration, basic calculations, sample preparation methods, common titrants, and examples of determining the equivalence point potential in redox reactions. The document also provides details on potentiometric titration and using a platinum electrode to monitor the potential during titration instead of an indicator.
This document contains an unsolved chemistry exam from 1995 containing 50 multiple choice questions testing concepts related to general chemistry, organic chemistry, and physical chemistry. The questions cover topics such as buffers in blood, protein structure, ATP generation from glucose, enzyme properties, organic reactions, acid-base properties, radioactivity, gas laws, and thermodynamics.
This document provides a 3-page summary of key concepts in organic chemistry:
- It begins with multiple choice questions about the structures of organic compounds including acids, alcohols, and alkanes.
- Questions then cover topics like polymers, hydrolysis, combustion of fuels, cracking of hydrocarbons, greenhouse gases, and the Contact process for making sulfuric acid.
- Diagrams are provided showing polymerization reactions, energy profiles, and fractional distillation of petroleum.
- The document concludes with questions about condensation polymers like nylon and terylene, homologous series of compounds, and separation techniques in oil refineries.
The document contains exam questions and answers related to hydrocarbons that can be used as fuels. Some key details include:
- Butane is a major component of LPG, which stands for liquefied petroleum gas.
- Methane is a major component of natural gas. Mercaptans are often added to natural gas to give it an odor to detect leaks. Methane's release contributes to the greenhouse effect and global warming.
- The heat of combustion of butane is calculated to be -2881 kJ/mol based on heats of formation of products and reactants.
This document summarizes research on converting lignin into liquid compounds through a solvolysis (alcoholysis) process. Lignin was heated to 270-300°C with an alcohol and acid in a high-pressure reactor. Key results include:
- Formic acid produced the highest pressures and yields of phenolic compounds, while acetic acid yielded mainly esters.
- Gas chromatography/mass spectrometry analysis showed the main products with formic acid were phenolic compounds, while acetic acid yielded esters like ethyl acetate and isopropyl acetate.
- Temperature reached 300°C within 75-90 minutes and pressure was regulated to not exceed 200 bars.
So in summary, this
Shift of Reaction Pathway by Added Chloride Ions in the Oxidation of Aromatic...Ratnakaram Venkata Nadh
Role of added chloride ions on the shift of reaction pathway of oxidation of aromatic ketones (acetophenone,
desoxybenzoin) by dichloroisocyanuric acid (DCICA) was studied in aqueous acetic acid—perchloric
acid medium. Participation of enolic and protonated forms of ketones in the rate determining steps is
manifested from zero and first orders with respect to the oxidant in absence and presence of added chloride
ions, respectively. Positive and negative effects of acid and dielectric constant on the reaction rate were
observed. The observations deduce plausible mechanisms involving (i) rate-determining formation of enol
from the conjugate acid of the ketone (SH+) in the absence of added chloride ions and (ii) rapid formation of
molecular chlorine species from HOCl (hydrolytic species of DCICA) in the presence of added chloride ions,
which then interacts with SH+ in a rate-determining step prior to the rapid steps of product formation. The
order of Arrhenius parameters substantiate the proposed plausible mechanisms based on order of reactants
both in presence and absence of added chloride ions.
Ethene is an alkene with the molecular formula C2H4. It is a colorless gas with a low boiling point and melting point. As an unsaturated hydrocarbon, ethene is more reactive than saturated hydrocarbons like ethane. It undergoes addition reactions where atoms or groups are added across the double bond, such as halogenation reactions with chlorine and bromine. Ethene also polymerizes through an addition reaction to form the polymer polyethene. It oxidizes when reacted with potassium manganate and combusts to form carbon dioxide and water.
Redox titrations involve adjusting the oxidation state of the analyte using an auxiliary oxidizing or reducing agent so that it can be titrated. Common reagents used in redox titrations include potassium permanganate, sodium thiosulfate, cerium sulfate, and potassium dichromate. Redox titrations are used to determine various analytes like ascorbic acid, hydrogen peroxide, iron, and calcium compounds. The document discusses the principles and procedures of important redox titrations like permanganometry, iodimetry, cerimetry, and dichrometry. It also describes the determination of water using the Karl Fischer reagent and reaction.
This document discusses various redox titration methods including permanganate, cerium, iodine, periodic acid, and sodium nitrite titrations. It provides details on relevant concepts such as redox equivalent weight calculations, types of indicators, and applications of different titration methods. Permanganate titrations can be direct, indirect, or residual and use potassium permanganate as the titrant. Cerium titrations use ammonium ceric sulfate and are advantageous over other methods. Sodium nitrite titration is used to determine primary aromatic amines. Periodic acid titration is used to determine polyhydroxy compounds by oxidation. Iodine titrations can be iodimetric or iod
K2Cr2O7 has the following key properties:
1. It forms orange crystals that melt at 669 K and are moderately soluble in cold water but less soluble in hot water.
2. It is a powerful oxidizing agent that oxidizes substances like I-, Fe2+, H2S, and SO2 in the presence of dilute sulfuric acid.
3. Its solutions change color from orange to yellow upon addition of an alkali due to the equilibrium between dichromate and chromate ions, and the color changes back to orange with an acid.
Inhibitory Effect of Some Carbazides on Corrosion of Aluminium in Hydrochloric Acid and Sodium Hydroxide Solutions
The dissolution of aluminium in hydrochloric acid and sodium hydroxide solutions in the presence of semicarbazide, thiosemicar- bazide and sym.dipheny1carbazide as corrosion inhibitors has been studied using thermometric, weight-loss and polarization methods. The three methods gave consistent results. The higher inhibition efficiency of these compounds in acidic than in alkaline madia may be due to the less negative potential of aluminium in hydrochloric acid solution, favouring adsorption of the additive.The adsorption of these compounds were found to obey Frurnkin adsorption isotherm. Cathodic polarization measurements showed that these com- pounds are cathodic inhibitors and their adsorption in the double layer does not change the mechanism of the hydrogen evolution reaction. The results are analysed in terms of both molecular and cationic adsorption.
Permanganometry, iodometry in analytical technique, P K MANIP.K. Mani
This document provides information about various redox titration methods including permanganometry, dichromatometry, iodometry, and iodimetry. It discusses the standard redox potentials and reaction equations for potassium permanganate, potassium dichromate, iodine, and other oxidizing agents. The document also describes procedures for standardizing and preparing standard solutions of these titrants. Specific applications discussed include the titration of iron(II), nitrites, and arsenite.
The document discusses redox reactions and equations. It provides examples of writing half-ionic equations for redox reactions involving complex ions such as permanganate (MnO4-), dichromate (Cr2O7 2-), and iodate (IO3-). It also discusses using titration to determine the stoichiometry of the reaction between iodine and thiosulfate ions.
This document summarizes research on using iron-based catalysts containing a second metal like magnesium or molybdenum for direct coal liquefaction. The key points are:
1) Iron-based catalysts containing magnesium or molybdenum as a second metal were tested for direct coal liquefaction.
2) Molybdenum increased catalyst activity the most, resulting in over 90% coal conversion at 400°C. Oil yields also increased significantly with molybdenum.
3) Tetralin and phenanthrene were used as solvents, with catalytic effects being more evident using phenanthrene as it is a poorer hydrogen donor.
Inhibition Effect of Hydantoin Compounds on the Corrosion of Iron in Nitric a...Al Baha University
The inhibition of corrosion of iron in 2M nitric acid and 2M sulfuric acid solutions by substituted phenylhydantoin, thiohydantoin, and dithiohydantoin compounds was measured using thermometric, weight loss, and polarization methods. The three methods gave consistent results. The polarization curves indicated that the hydantoin compounds act as mixed-type inhibitors. The adsorption of the inhibitors were found to obey the Temkin adsorption isotherm. The higher inhibition ef®ciency of the additives in nitric with respect to sulfuric acid solution may be attributed to the reduced formation of soluble quaternary nitrogen salts in nitric acid medium, favouring adsorption of the parent additive on the metal surface. The obtained results indicate that the corrosion rate of iron in both acids increases with increasing temperature, both in absence and presence of the tested inhibitors. Kinetic-thermodynamic model functions and Temkin isotherm data are compared and discussed. The synergistic effect of halide anions on the inhibition ef®ciency of the hydantoin compounds was also investigated.
I apologize, I do not have enough context to determine what is being referred to based on the single quote provided. Could you please provide some additional details or context about the quote?
Este documento presenta una lista de productos de cajas y interruptores para fusibles para automóviles y camiones de marcas como Volkswagen, Ford, GM, Fiat y más. Se proporcionan números de referencia, descripciones breves y aplicaciones vehiculares de cada producto.
3 the itchy patient cases- austel finalwithpollseyedogtor
This document summarizes key points from a veterinary dermatology symposium. It discusses diagnostic steps and treatment options for common pruritic conditions in dogs and cats. Common causes of pruritus include demodicosis, cheyletiella, dermatophytosis, pyoderma, bacterial/fungal infections, parasites, and allergies. The document emphasizes the importance of thorough diagnostics before initiating treatment, as well as long-term management for chronic allergic conditions through elimination diets and immunotherapy. Compliance can be challenging but is critical for successful management of pruritic patients.
The document discusses the history and versions of the content management system Joomla. It describes the major releases including Joomla 1.0, 1.5, 1.6/1.7, and the current version 2.5. The key components and considerations for upgrading Joomla sites are also outlined, such as verifying compatibility of components, modules, plugins and templates, and whether an upgrade will require a new installation or is a simple process. Tips are provided on finding appropriate third party tools on the Joomla website.
This poem uses repetition of the letter "i" in a variety of one-syllable words to create a pattern. The words are arranged in lines and columns with similar starting letters grouped together, using the repeated sound of "i" throughout the text.
Inhibition of Copper Corrosion by Arylazotriazoles in Nitric Acid Solution Al Baha University
. A study has been made to investigate the effect of some azoheterocyclic dyes of the type 3-arylazo 1,2,4-triazole (AT) on the corrosion of copper exposed to 0.5M nitric acid solution at different temperatures and at different AT concentrations. Using potentiodynamic polarization and Tafel electrochemical methods, it can be shown that AT compounds are good inhibitors of copper corrosion in HNO 3 solution. The kinetic and thermodynamic parameters of the inhibited system were determined. The high inhibition efficiency of these compounds may be due to the adsorption of the additive itself and/or the adsorption of the formed Cu(II)-AT complexes at the polarized electrode interface. Cathodic polarization measurements showed that AT dyes are predominantly cationic inhibitor
This document contains an unsolved chemistry exam from 1995 containing 50 multiple choice questions testing concepts related to general chemistry, organic chemistry, and physical chemistry. The questions cover topics such as buffers in blood, protein structure, ATP generation from glucose, enzyme properties, organic reactions, acid-base properties, radioactivity, gas laws, and thermodynamics.
This document provides a 3-page summary of key concepts in organic chemistry:
- It begins with multiple choice questions about the structures of organic compounds including acids, alcohols, and alkanes.
- Questions then cover topics like polymers, hydrolysis, combustion of fuels, cracking of hydrocarbons, greenhouse gases, and the Contact process for making sulfuric acid.
- Diagrams are provided showing polymerization reactions, energy profiles, and fractional distillation of petroleum.
- The document concludes with questions about condensation polymers like nylon and terylene, homologous series of compounds, and separation techniques in oil refineries.
The document contains exam questions and answers related to hydrocarbons that can be used as fuels. Some key details include:
- Butane is a major component of LPG, which stands for liquefied petroleum gas.
- Methane is a major component of natural gas. Mercaptans are often added to natural gas to give it an odor to detect leaks. Methane's release contributes to the greenhouse effect and global warming.
- The heat of combustion of butane is calculated to be -2881 kJ/mol based on heats of formation of products and reactants.
This document summarizes research on converting lignin into liquid compounds through a solvolysis (alcoholysis) process. Lignin was heated to 270-300°C with an alcohol and acid in a high-pressure reactor. Key results include:
- Formic acid produced the highest pressures and yields of phenolic compounds, while acetic acid yielded mainly esters.
- Gas chromatography/mass spectrometry analysis showed the main products with formic acid were phenolic compounds, while acetic acid yielded esters like ethyl acetate and isopropyl acetate.
- Temperature reached 300°C within 75-90 minutes and pressure was regulated to not exceed 200 bars.
So in summary, this
Shift of Reaction Pathway by Added Chloride Ions in the Oxidation of Aromatic...Ratnakaram Venkata Nadh
Role of added chloride ions on the shift of reaction pathway of oxidation of aromatic ketones (acetophenone,
desoxybenzoin) by dichloroisocyanuric acid (DCICA) was studied in aqueous acetic acid—perchloric
acid medium. Participation of enolic and protonated forms of ketones in the rate determining steps is
manifested from zero and first orders with respect to the oxidant in absence and presence of added chloride
ions, respectively. Positive and negative effects of acid and dielectric constant on the reaction rate were
observed. The observations deduce plausible mechanisms involving (i) rate-determining formation of enol
from the conjugate acid of the ketone (SH+) in the absence of added chloride ions and (ii) rapid formation of
molecular chlorine species from HOCl (hydrolytic species of DCICA) in the presence of added chloride ions,
which then interacts with SH+ in a rate-determining step prior to the rapid steps of product formation. The
order of Arrhenius parameters substantiate the proposed plausible mechanisms based on order of reactants
both in presence and absence of added chloride ions.
Ethene is an alkene with the molecular formula C2H4. It is a colorless gas with a low boiling point and melting point. As an unsaturated hydrocarbon, ethene is more reactive than saturated hydrocarbons like ethane. It undergoes addition reactions where atoms or groups are added across the double bond, such as halogenation reactions with chlorine and bromine. Ethene also polymerizes through an addition reaction to form the polymer polyethene. It oxidizes when reacted with potassium manganate and combusts to form carbon dioxide and water.
Redox titrations involve adjusting the oxidation state of the analyte using an auxiliary oxidizing or reducing agent so that it can be titrated. Common reagents used in redox titrations include potassium permanganate, sodium thiosulfate, cerium sulfate, and potassium dichromate. Redox titrations are used to determine various analytes like ascorbic acid, hydrogen peroxide, iron, and calcium compounds. The document discusses the principles and procedures of important redox titrations like permanganometry, iodimetry, cerimetry, and dichrometry. It also describes the determination of water using the Karl Fischer reagent and reaction.
This document discusses various redox titration methods including permanganate, cerium, iodine, periodic acid, and sodium nitrite titrations. It provides details on relevant concepts such as redox equivalent weight calculations, types of indicators, and applications of different titration methods. Permanganate titrations can be direct, indirect, or residual and use potassium permanganate as the titrant. Cerium titrations use ammonium ceric sulfate and are advantageous over other methods. Sodium nitrite titration is used to determine primary aromatic amines. Periodic acid titration is used to determine polyhydroxy compounds by oxidation. Iodine titrations can be iodimetric or iod
K2Cr2O7 has the following key properties:
1. It forms orange crystals that melt at 669 K and are moderately soluble in cold water but less soluble in hot water.
2. It is a powerful oxidizing agent that oxidizes substances like I-, Fe2+, H2S, and SO2 in the presence of dilute sulfuric acid.
3. Its solutions change color from orange to yellow upon addition of an alkali due to the equilibrium between dichromate and chromate ions, and the color changes back to orange with an acid.
Inhibitory Effect of Some Carbazides on Corrosion of Aluminium in Hydrochloric Acid and Sodium Hydroxide Solutions
The dissolution of aluminium in hydrochloric acid and sodium hydroxide solutions in the presence of semicarbazide, thiosemicar- bazide and sym.dipheny1carbazide as corrosion inhibitors has been studied using thermometric, weight-loss and polarization methods. The three methods gave consistent results. The higher inhibition efficiency of these compounds in acidic than in alkaline madia may be due to the less negative potential of aluminium in hydrochloric acid solution, favouring adsorption of the additive.The adsorption of these compounds were found to obey Frurnkin adsorption isotherm. Cathodic polarization measurements showed that these com- pounds are cathodic inhibitors and their adsorption in the double layer does not change the mechanism of the hydrogen evolution reaction. The results are analysed in terms of both molecular and cationic adsorption.
Permanganometry, iodometry in analytical technique, P K MANIP.K. Mani
This document provides information about various redox titration methods including permanganometry, dichromatometry, iodometry, and iodimetry. It discusses the standard redox potentials and reaction equations for potassium permanganate, potassium dichromate, iodine, and other oxidizing agents. The document also describes procedures for standardizing and preparing standard solutions of these titrants. Specific applications discussed include the titration of iron(II), nitrites, and arsenite.
The document discusses redox reactions and equations. It provides examples of writing half-ionic equations for redox reactions involving complex ions such as permanganate (MnO4-), dichromate (Cr2O7 2-), and iodate (IO3-). It also discusses using titration to determine the stoichiometry of the reaction between iodine and thiosulfate ions.
This document summarizes research on using iron-based catalysts containing a second metal like magnesium or molybdenum for direct coal liquefaction. The key points are:
1) Iron-based catalysts containing magnesium or molybdenum as a second metal were tested for direct coal liquefaction.
2) Molybdenum increased catalyst activity the most, resulting in over 90% coal conversion at 400°C. Oil yields also increased significantly with molybdenum.
3) Tetralin and phenanthrene were used as solvents, with catalytic effects being more evident using phenanthrene as it is a poorer hydrogen donor.
Inhibition Effect of Hydantoin Compounds on the Corrosion of Iron in Nitric a...Al Baha University
The inhibition of corrosion of iron in 2M nitric acid and 2M sulfuric acid solutions by substituted phenylhydantoin, thiohydantoin, and dithiohydantoin compounds was measured using thermometric, weight loss, and polarization methods. The three methods gave consistent results. The polarization curves indicated that the hydantoin compounds act as mixed-type inhibitors. The adsorption of the inhibitors were found to obey the Temkin adsorption isotherm. The higher inhibition ef®ciency of the additives in nitric with respect to sulfuric acid solution may be attributed to the reduced formation of soluble quaternary nitrogen salts in nitric acid medium, favouring adsorption of the parent additive on the metal surface. The obtained results indicate that the corrosion rate of iron in both acids increases with increasing temperature, both in absence and presence of the tested inhibitors. Kinetic-thermodynamic model functions and Temkin isotherm data are compared and discussed. The synergistic effect of halide anions on the inhibition ef®ciency of the hydantoin compounds was also investigated.
I apologize, I do not have enough context to determine what is being referred to based on the single quote provided. Could you please provide some additional details or context about the quote?
Este documento presenta una lista de productos de cajas y interruptores para fusibles para automóviles y camiones de marcas como Volkswagen, Ford, GM, Fiat y más. Se proporcionan números de referencia, descripciones breves y aplicaciones vehiculares de cada producto.
3 the itchy patient cases- austel finalwithpollseyedogtor
This document summarizes key points from a veterinary dermatology symposium. It discusses diagnostic steps and treatment options for common pruritic conditions in dogs and cats. Common causes of pruritus include demodicosis, cheyletiella, dermatophytosis, pyoderma, bacterial/fungal infections, parasites, and allergies. The document emphasizes the importance of thorough diagnostics before initiating treatment, as well as long-term management for chronic allergic conditions through elimination diets and immunotherapy. Compliance can be challenging but is critical for successful management of pruritic patients.
The document discusses the history and versions of the content management system Joomla. It describes the major releases including Joomla 1.0, 1.5, 1.6/1.7, and the current version 2.5. The key components and considerations for upgrading Joomla sites are also outlined, such as verifying compatibility of components, modules, plugins and templates, and whether an upgrade will require a new installation or is a simple process. Tips are provided on finding appropriate third party tools on the Joomla website.
This poem uses repetition of the letter "i" in a variety of one-syllable words to create a pattern. The words are arranged in lines and columns with similar starting letters grouped together, using the repeated sound of "i" throughout the text.
Inhibition of Copper Corrosion by Arylazotriazoles in Nitric Acid Solution Al Baha University
. A study has been made to investigate the effect of some azoheterocyclic dyes of the type 3-arylazo 1,2,4-triazole (AT) on the corrosion of copper exposed to 0.5M nitric acid solution at different temperatures and at different AT concentrations. Using potentiodynamic polarization and Tafel electrochemical methods, it can be shown that AT compounds are good inhibitors of copper corrosion in HNO 3 solution. The kinetic and thermodynamic parameters of the inhibited system were determined. The high inhibition efficiency of these compounds may be due to the adsorption of the additive itself and/or the adsorption of the formed Cu(II)-AT complexes at the polarized electrode interface. Cathodic polarization measurements showed that AT dyes are predominantly cationic inhibitor
The document discusses the Catholic sacrament of Holy Communion/Eucharist. It describes Communion as receiving the body, blood, soul and divinity of Jesus during Mass. The rituals include bringing gifts to the altar, presenting and breaking bread. To receive Communion one must be free from mortal sin and prepare through prayer. While non-Christians cannot receive it, they can be present and pray for unity.
Egypt presdent رئيس مصر - دليلك لاحتيار الرئيس - ليقود للازدهر و النمو - بمي...Ibrahimia Church Ftriends
كيف تختار رئيس من المرشحيين للرئاسه
بطريقه علميه
ابعد عن تقديراتك اى مؤثرات عاطفيه او تأثيرات للمصلحه تفكير جادى
حتى لو كان مختلف معك فى التيارات الفكريه
كن امين فى الحكم
انسى الشخص الذى تحبه
عشرة نقاط تكون مرشدا واضحا لاختيار الرئيس االذى تريده ان يقود البلاد بالمحبه للإزدهار و الرفاهيه
ميزان القياده
Talybe bioequo - detergenti biologici ed equosolidali alla spinaLiberoMondo
Da dove arrivano le materie prime che compongono i detersivi Talybe?
Perché puntare molto sulla formula del prodotto sfuso in bottega?
Perché il riuso è parecchio più vantaggioso di qualsiasi altro tipo di riciclo, e quali studi concreti lo dimostrano?
Scaricate l'agevole e sintetica guida in pdf che, passo dopo passo, risponde a queste ed altre domande e svela le principali caratteristiche e specificità di una linea di prodotti che è entrata ormai in molte case e ha aiutato migliaia di persone a rendere "bioeque" tante piccole ma importantissime attività quotidiane.
Paul Sansone Jr. – Relationship Selling – Developer of Technology for today’s...Sean Bradley
1) The document discusses how the auto sales industry has changed from a relationship-based model in the past to a more online and price-focused model currently.
2) It promotes the EZ Referral Network program which provides training and technology to help salespeople generate their own leads through relationships, referrals, and networking rather than relying on dealership leads.
3) The goal is to change the sales culture to one where salespeople are business owners who can grow their customer base organically and make more money through relationship-selling and repeat/referral business.
GODAN: A solution, as a customizable dissemination gateway to agri-food resea...cthanopoulos
Presentation "A solution, as a customizable dissemination gateway to agri-food research information" in the workshop "Creating Impact with Open Data in Agriculture and Nutrition", in the framework of the GODAN initiative on Global Open Data for Agriculture and Nutrition, 19/20 January 2015, Wageningen, The Netherlands
1) The study investigated the inhibition of iron corrosion in nitric and sulfuric acid solutions by various hydantoin compounds using thermometric, weight loss, and polarization methods.
2) The hydantoin compounds were found to act as mixed-type inhibitors, reducing both the anodic and cathodic reaction rates. The inhibition efficiency increased with increasing compound concentration and followed the Temkin adsorption isotherm model.
3) Polarization curves showed that 3-carbethoxy-1-phenylhydantoin was the most effective inhibitor, likely due to its ability to adsorb onto the iron surface through nitrogen and oxygen atoms. Temperature studies found that corrosion rates increased with temperature in both inhibited and un
Spectral studies of 5-({4-amino-2-[(Z)-(2-hydroxybenzylidene) amino] pyrimidi...IOSR Journals
Some transition metal ions Complexes with 5-({4-amino-2-[(Z)-(2-hydroxybenzylidene) amino]
pyrimidin-5-yl} methyl)-2,3,4-trimethoxybenzene were prepared and characterized by elemental analyses,
Infrared , magnetic moment, electronic spectra , mass spectra, X-ray powder diffraction, molar conductance
and thermal analysis (TGA). The complexes have general formulae [ML2.2H2O] {where M = Mn (II), Co (II), Ni
(II), Cu (II), Zn (II), Pd (II) and Pt (II). The coordination behavior of the metal ions towards to the investigated
Schiff base takes place through –C=N,-NH2 and –OH groups. The obtained C, H and N elemental analysis data
showed the Metal: Ligand ratio is 1:2 [M: L] ratio. The molar conductance data reveal that all the metal
complexes are non-electrolytic in nature. From the magnetic moments the complexes are paramagnetic except
Zn metal ion complexes have octahedral geometry with coordination number eight. The thermal behavior of
these complexes shows that, the hydrated complexes have loses two water molecules and immediately followed
by decomposition of the anions and ligand molecules in the second and third stage. The Schiff bases and metal
complexes show good activity against some bacteria. The antimicrobial results indicate that, the metal
complexes have better antimicrobial activity as compared to the prepared Schiff base.
Absence and presence organic and inorganic inhibitorsAlexander Decker
This document summarizes research on the corrosion of copper metal in nitric acid solutions and the inhibitive effects of organic and inorganic additives. Key findings include:
- The rate of copper dissolution increases with increasing nitric acid concentration due to the highly exothermic reaction.
- Organic compounds like phenylhydrazine, urea, and thiourea, as well as inorganic compounds like sodium chromate, sodium tungstate, and sodium phosphate were found to inhibit copper corrosion by adsorbing to the metal surface.
- Inhibition efficiency increased with increasing concentrations of the organic and inorganic additives and followed different sequences based on the chemical structure of the additive.
The document discusses general principles of metallurgy including the chief modes of occurrence of metals based on standard electrode potential, Ellingham diagrams for reduction of metal oxides using carbon and CO as reducing agents, electrolytic reduction processes, hydrometallurgy processes like cyanide process for silver and gold, methods of metal purification like electrolysis, zone refining, and more. It also discusses concepts like standard electrode potential, how to calculate electrode potential from standard reduction potentials, electrochemical series, how the ease of metal oxide reduction can be determined from an Ellingham diagram based on thermodynamic stability, and applications and limitations of Ellingham diagrams.
The document discusses the inhibitory effect of semicarbazide, thiosemicarbazide, and sym-diphenylcarbazide on the corrosion of aluminum in hydrochloric acid and sodium hydroxide solutions. Thermometric, weight-loss, and polarization methods were used to study the effect. The inhibitors showed higher inhibition efficiency in acidic solutions than alkaline solutions. The inhibitors were found to be cathodic inhibitors that adsorb onto the aluminum surface. Adsorption of the inhibitors followed the Frumkin isotherm and increased in the order: sym-diphenylcarbazide > thiosemicarbazide > semicarbazide.
Graphene oxide immobilized copper phthalocyanine tetrasulphonamide: the first...Pawan Kumar
The first successful synthesis of DMC directly from methanol and carbon dioxide using a heterogenized
homogeneous graphene oxide immobilized copper phthalocyanine tetrasulphonamide catalyst in the
presence of N,N0-dicyclohexylcarbodiimide (DCC) as a dehydrating agent is described. The presence of a
dehydrating agent was found to be vital and in its absence the yield of DMC was found to be decreased
significantly. Under the optimized reaction conditions, the maximum yield of DMC reaches up to 13.3%.
Although the homogeneous copper phthalocyanine tetrasulphonamide catalyst provided a little higher
yield of DMC (14.2%), the facile recovery and recycling ability of the heterogeneous catalyst make the
developed method more attractive from environmental and economical viewpoints.
This document summarizes a study on the speciation of technetium peroxo complexes formed from the reaction of Tc(+7) with hydrogen peroxide (H2O2) in sulfuric acid (H2SO4). UV-visible and 99-Tc NMR spectroscopy were used to characterize the species. In highly concentrated H2SO4 (≥9 M) and low H2O2 (0.17 M), blue solutions formed containing proposed Tc(+7) peroxo complexes. In 6 M H2SO4 and higher H2O2 (≥2.12 M), red solutions formed containing the species TcO(O2)2(H2O)(OH). The UV
synthesis and characterization of hydrazone ligand and their metal complexesMUBASHIRA M
This slide mainly contain the synthesis, characterization of a few hydrazine based heterocyclic ligand such as hydralazone and phenyl hydralazone and also their metal complexes. so in this work, my aim is to synthesise the ligands; 2-thiophenecarboxylaldehydehydralazone and 2,3-butanedionephenylhydrazone. also to characterized the synthesised hydrazones by different physiochemical techniques.
Studies On The Cobalt(II) And Copper(II) Complexes Of 2,5-Substituted 1,3,4-T...IOSR Journals
1. New metal complexes of Co(II) and Cu(II) were synthesized by reacting solutions of the metal salts with 2,5-substituted 1,3,4-triazole ligands in an alcoholic medium.
2. The complexes were characterized through techniques such as elemental analysis, magnetic susceptibility, molar conductance, and IR spectroscopy.
3. Based on analytical data and characterization, the complexes were determined to have a 1:2 metal to ligand ratio and the ligand was found to act as a bidentate ligand coordinating through nitrogen atoms in the ring.
1. The document discusses several chemistry problems and their solutions.
2. Questions cover topics like organic reactions, equilibrium constants, ionization, isoelectronic species, and more.
3. Correct answers and step-by-step workings are provided for each problem.
A study on photocatalytic activity of micro arc oxidation ti o2 filmsssuser195344
This document discusses a study on the photocatalytic activity of micro-arc oxidation (MAO) TiO2 films and Ag+/MAO-TiO2 composite films. MAO-TiO2 films were prepared on titanium substrates using a phosphate-based electrolyte. The films were then impregnated with silver ions (Ag+) to create Ag+/MAO-TiO2 composite films. The films were characterized using SEM, XRD, and EDS. Their photocatalytic activity was evaluated by measuring the degradation of methylene blue dye under simulated sunlight irradiation. The results showed that Ag+ impregnation enhanced the photocatalytic activity of the MAO-TiO2 films.
Reduction - Oxidation Titrations Theory and Application.pptAbdelrhman abooda
This document discusses redox (oxidation-reduction) titrations. It begins by defining redox reactions and key terms like oxidizing agent and reducing agent. It then discusses oxidation numbers and how to calculate them. Several examples of oxidation numbers are provided. The document also covers balancing redox reactions using the half-reaction method. Factors that affect oxidation potential are explained, including common ions, pH, complexing agents, and precipitating agents. Standard reduction potentials of various redox couples are presented. Finally, the shape of a typical redox titration curve is briefly described.
This document summarizes a research article that studied the selective oxidation of styrene using Mg-Co-Al hydrotalcite-like catalysts with air as the oxidant. Several Mg-Co-Al catalysts with varying Co content were synthesized and characterized. The catalysts were tested for styrene oxidation and showed good activity and stability. Both styrene conversion and product selectivity depended on the cobalt substitution level. Cobalt ions within the hydrotalcite lattice acted as active sites for styrene epoxidation.
This document summarizes the synthesis and characterization of three heterometallic lanthanide-titanium oxo-clusters with the formula [LnTi11O16(NO3)2(OiPr)17]·3H2O, where Ln is Sm, Eu, or Gd. Single crystal X-ray diffraction revealed they have an LnTi11 cage structure. Compound 2 containing Eu3+ exhibits characteristic red fluorescence due to energy transfer from the Ti11 oxo-cluster. Compound 2 also shows potential as a fluorescent labeling agent and photocatalyst for dye degradation, as its fluorescence intensity increases with 1,10-phenanthroline and it catalyzes dye degradation on paper.
This document provides an overview of iron nitrosyl compounds. It discusses the properties of nitric oxide and how metal nitrosyl complexes are synthesized industrially and in the lab. Specifically, it describes a laboratory experiment where bis(diethyldithiocarbamato)nitrosyl iron (Fe(NO)dtc2) is synthesized from ferrous sulfate and sodium nitrite. This is then reacted with iodine to form bis(diethyldithiocarbamato)(iodo)nitrosyl iron (FeI(NO)dtc2). Both complexes are characterized using infrared spectroscopy, NMR spectroscopy, and EPR spectroscopy to analyze the nitrosyl ligand bonding.
This document summarizes a study that investigated three copper(II) imidazolate frameworks as photocatalysts for reducing CO2 into methanol under visible light irradiation. The frameworks were synthesized via hydrothermal or precipitation reactions and characterized using various techniques. Their photocatalytic activities for CO2 reduction and methylene blue degradation were evaluated. Results showed the orthorhombic copper(II) imidazolate framework with a band gap of 2.49 eV and green color exhibited the best photocatalytic activity for CO2 reduction, producing 1712.7 μmol/g of methanol over 5 hours. Its synergistic small band gap and crystal structure were determined to be critical factors for its performance.
A ruthenium-carbamato-complex derived from a siloxylated amine and carbon dio...Pawan Kumar
The rutheniumcarbamate complex derived from3-trimethoxysilyl-1-
propyl amine and carbon dioxidewas found to be a novel catalyst for
the oxidative cyanation of aromatic and cyclic tertiary amines to
corresponding a-amino nitriles in high to excellent yields by using
hydrogen peroxide and molecular oxygen as enviro-economic
oxidants. The developed protocol suggested an efficient alternative
for recycling carbon dioxide.
physical chemisrty of ironmaking reduction processIIT Kanpur
- The blast furnace uses both direct and indirect reduction processes to reduce iron oxides and other metal oxides. Direct reduction involves reaction with carbon, while indirect reduction uses carbon monoxide and hydrogen gases.
- Temperature profiles in the blast furnace vary significantly, reaching over 2000°C in front of the tuyeres and decreasing to around 200°C for exhaust gases and 1300-1500°C in the hearth.
- The reduction of various metal oxides depends on the oxygen potential of the oxides and reductants used. Oxides with higher oxygen potentials reduce at lower temperatures than those with lower oxygen potentials.
2. 1088 L.H. Madkouret al.
Results and Discussion
Inhibitor's effect on corrosion
Potentiodynamic measurements were performed in the presence of different
concentrations of arylazotriazole dyes added to 0.5 M HNO 3 solutions at 295 K.
The results are shown in Table 1 and Fig. 1. The three arylazotriazole dyes D1, D2,
and D3 attain an optimum inhibition of > 95% at a concentration of 10.4 M. The
high inhibition efficiency of the applied dyes towards copper can be explained as
follows. As the dye molecule approaches the electrode surface, the electric field of
the double layer increases the polarization of the molecule and induces additional
charges on both the N and O atoms, thus enhancing the adsorption of the dye
molecule. In the case of D1and D2, the formation of Cu(II)-dye complexes in solution
can be assumed which consequently are adsorbed at the electrode surface. The
formation of these complexes between Cu 2÷ and D1 or D2 and the mechanism of
their chelation was explained by a proton displacement from the phenolic OH group
by the Cu 2+ ion [6]. Thus, the bonding of the Cu 2÷ ion to the dye molecule takes
place through a covalent linkage with the oxygen of the phenolic group, whereas
the N=N group contributes to a coordination bond as follows:
N--TN:N~O /OH2
L _N ~ Cu--H20
-Y" 1".o
H H20
Cu(ll)-D1complex
H
I
f NN Me
N- ~1 N%
H20 N~,~ ))
o_o_o
t OH2
~ / %N--~-- N
Me I~.
"~N/
I
H
Cu(II)-D2complex(1:2;at highconcentrationof D2)
H2Ox." ?H2
/______~O-- (iu NO2
~( ))-~N. OH2
~"/ ~N~N
Me 1~.
--.Nj
I
H
Cu(II)-D2 complex (1:1; at low concentration of £)2)
3. Inhibition of Copper Corrosion 1089
•I.gO~ . Free acid /tg
xxxxx 1xlt~'M O1 //;J /
...... 1,1o4Mo2 I,': /
..... ,,,o,Mo3 /# /
+20C /'g
j
+I00 ~~, ~"'~
-10C -.... "-....... ,% ,,
-20C ""-... ""-%
%.,.
I ] I i , I
103 10z 105 106 107 108 109
i, n ,4 cm -2
Fig. 1. Potentiodynamic polarization curves of Cu in 0.5 M HNO 3 alone and containing 10-4M
arylazotriazoles (Dx, D2, and D3) at 295 K
LU
t~
(b
25
1.5
0.5-
2OO
f~
400 600
wovelengfh~rim
Fig. 2. Absorption spectra of Cu in 0.5 M HNO 3con-
taining l0 -4 M D2; : no corrosion; .:
corrosion at 313 K; xxxx: corrosion at 333 K
+0.35
+0.15
z,, -O.O5
- 0..25
-0.~5
÷0.25
,-, //
",, .,">. i '
" ",~,i"
, _t , I , 1
*0.05 -0.15 -q35
E(v vs. ,4g*)
Fig. 3. Cyclic voltammograms of Cu in 0.5 M
, HNO3 containing I0-4M D 3 ; - - : no
-0.50 corrosion; ; corrosion at 295K;
..... : corrosion at 333 K
5. InhibitionofCopperCorrosion 1091
Cu 2 + complexes readily forms with the title dyes D1 and D2; it has been proved that
the ratio of the metal ion to the ligand either is 1:1 or 1:2. The structure of the
resulted complexes was substantiated by their analytical data, by cyclic voltammetry,
and by spectral analysis (mainly ultraviolet spectra) as shown in Figs. 2 and 3.
The inhibition effect of the three studied arylazotriazole compounds D1, D2, and
D3 are likely due to the interaction of the adsorbed dye molecules with the Cu 2+
ions at the electrode surface formed during the polarization at the interface via the
triazole ring forming a chemisorbed complex [7]. From Table 1, Ecorrbecomes more
negative at the addition of the inhibitors which indicates that these tested dyes are
predominantly effective in the cathodic region.
Tqfel constantsfor Cu corrosion
The cathodic Tafel constant (CTC) in the free nitric acid solution corresponds to
oxygen reduction, whereas the higher anodic Tafel constant (ATC) values (Table 1)
mainly correspond to the dissolution reactions [8] as fellows:
Cu~Cu ++e- and Cu~Cu 2++2e-
At different concentrations of the tested 3-arylazo 1,2,4-triazoles, it was found that
CTC varied from 66-170 inV. dec-l, whereas ATC changed from 73-141 mV-dec-1.
These higher Tafel constant values support the probability of the presence of a
complicated surface processes involving Cu ions and AT molecules. Moreover, Tafel
slopes of about 90 mV.dec-1 can be attributed to a surface kinetic process rather
than a diffusion controlled process [91.
Temperature effect on corrosion
Ioorrand Rcorrincrease with increasing temperature as shown in Table 2. This is due
to the thermal activation of the surface polarization of the following reactions:
Cu~Cu ++e- and Cu~Cu 2++2e-
The increase of Rco~ris due to the absence of protective oxide layers at the Cu surface
in nitrate medium. Thus, the increase of temperature enhances both the copper
corrosion and the additive desorption processes without leading to Cu(II)-AT
complex formation. For O2, the inhibiting efficiency value decreased to 56~o at
313 K, then increased again to 83~ at 343 K. It was also found that the colour of the
electrolyte solution containing D2 changed from yellow to reddish at 313 K and
became violet at higher temperatures. The phenomenon of the colour changes for the
inhibitor D2 can be explained as follows:
(1) The transformation of the tetrahedral Cu(II)-D2 complex into the octahedral form
by coordination of two solvent molecules leads to the six coordinate complex.
(2) The thermochromic property of Cu-D2 chelates results from a changed
resonance by chelate ring formation; this is due to the intramolecular H-bond
and/or metal chelation.
The effect of temperature on the potentiodynamic polarization plot of Cu
exposed to 0.5M HNO3 acid and in the presence of inhibitor Dz is plotted in Fig. 4.
6. 1092 L.H. Madkour et al.
Table 2. Effect of temperature on the corrosion parameters of Cu in 0.5 M HNO 3 in absence and in
presence of 1 x 10-4M AT, 295 ~< T~< 343K
System Temp. Rp x 10 -2 I .... R .... E ....
(K) (f~) (#A'cm -2) (MPY) (mV vs. SCE)
0.5 M HNO3 295 0.1870 1609.00 1483.00 + 54
333 0.1470 2839.00 2617.00 + 22
343 0.1159 3862.00 3561.00 + 27
0.5 M HNO 3 295 4.9810 47.86 44.13 - 11
+ D1 303 3.0830 99.85 92.06 + 8
313 2.7870 111.10 102.40 + 3
323 0.8687 308.10 284.00 + 11
333 0.3867 1009.00 930.70 + 17
343 0.2690 1508.00 1390.00 + 19
0.5 M HNO 3 295 3.2910 67.32 62.07 - 34
+ D 2 303 1.3200 261.20 240.80 - 341
313 0.2771 2357.00 2173.00 -213
323 0.3188 1177.00 1085.00 - 149
333 0.2778 1249.00 1151.00 - 121
343 0.6696 631.70 582.40 + 2
0.5 M HNO3 295 3.8400 43.57 40.17 - 12
+ D 3 303 2.7560 62.54 57.66 - 81
313 2.8230 93.29 86.01 - 34
323 1.4700 189.30 174.50 -21
333 0.3965 874.60 806.30 + 1
+ 800
+ 600
.4-400
+200
u2 o.o
-200
-400
g
g
2
2
• i /@.,. :
44-+
..... ...... _.--'- ......
[ i ~ I I
103 10g 105 106 107 108 109
i, nAcm -2
Fig. 4. Potentiodynamic polarization curves of Cu in 0.5 M HNO 3 containing 10 .4 M D 2 at different
temperatures; : 303 K; .: 313 K; ...... ".333 K; xxxxx: 343 K
7. Inhibition of Copper Corrosion 1093
8
6
2
2
"*, .... D1
'~ - - D2,k.I ..... D3
~__L(K ) '~
I"
Fig.5. logk vs. 1/T plot of Cu in 0.5M HNO3
x I0" containing 10 4M arytazotriazole dyes; xxxxx:
D1; : D2;..... : D3
It is clear that the passive layer region decreases as the temperature increases. Thus,
D2 may act as an anodic inhibitor rather than a cathodic one, whereas Ecorrbecomes
more positive as the temperature increases (Table 2 and Fig. 4).
The UV spectroscopic investigations and cyclic voltammetric analyses of the
electrolyte solutions containing D2 and/or D3 at different temperatures are plotted
in Figs. 2 and 3, respectively. Before the corrosion process, a strong absorption peak
at 303 nm was observed, corresponding to the azo group. During the corrosion
processes, another additional broad absorption band was recorded at 542nm,
corresponding to the formation of the Cu(II)-D2 complex in solution (Fig. 2).
Cyclic voltammetric analysis of the electrolyte solution containing 10-4M D3
(Fig. 3) revealed one redox peak before the corrosion process. During corrosion at
different temperatures, another additional redox shoulder and redox peak were
observed corresponding to the stepwise reduction of the free Cu 2+ ions present in
solution.
Both UV spectral and cyclic voltammetric analyses indicate that the increase of
temperature enhances both the Cu corrosion and the dye desorption processes.
Kinetic and thermodynamic parameters
The activation energy (AE#) for the copper corrosion in 0.5 M HNO 3 containing
10--4M of different inhibitors (D1, D2, and D3) was calculated from Eyring's
equation k = KTexp [10]. It was found that AE# increases in the order
D2 > D3 > D 1. An Arrhenius plot indicating the variation of log k or logRcorr with
the temperature is shown in Fig. 5. The higher entropy value (AS#) in the case of D2
compared to the values ofD 1and D3 as shown in Table i indicates a slower reaction
[11].
Conclusion
The general corrosion of Cu exposed to 0.5 M HNO 3 solution containing arylazo
1,2,4-triazole (AT) dyes can be summarized as follows:
(1) A higher corrosion inhibition efficiency was observed for Cu exposed to 0.5 M
HNO 3 solution containing A T compounds due to the formation of Cu(II)-A T
complexes at the polarized electrode surface. The adsorption process is
endothermic in nature and causes a reasonable of corrosion inhibition at high
temperatures.
8. 1094 L.H. Madkour et al.
(2)
(3)
The Cu corrosion inhibition process due to the formation of Cu(II)-AT
complexes is entropy controlled rather than activation energy controlled, since
the activation energy values are relatively high (Table 1).
The higher cathodic Tafel constant value in free acid (0.5 M HNO3) is attributed
to the oxygen reduction, whereas the anodic Tafel constant value represents the
Cu dissolution. After addition of the AT compounds, the cathodic and anodic
reactions mainly involve A T molecules, i.e. a surface kinetic controlled process
takes place.
Experimental
The copper metal (99.99~ Copper Egyptian Company) was used as foils with a surface area of
1-1.3 cm 2, containing 0.001~oPb as impurity. These foils were sealed in glass tubes using epoxy resin.
The copper electrodes were mechanically polished and rinsed in an ultrasonic bath containing distilled
water before each experiment.
A stock solution of HNO3 (0.5M) was prepared. Potentiodynamic measurements were maintained
using a computerized corrosion measurement console 350 A-PARC (from EG & G) connected to a
K-47 corrosion cell containing twin high density, non-permeable graphite counter electrodes and a
saturated calomel electrode (SCE) fitted in a bridge tube incorporating an ultra-low leakage Vycor
frit. The cell was immersed in a thermostatted water bath. In the Tafel condition, a controlled potential
scan was applied to the copper electrode starting at E.... and extending in either the anodic or the
cathodic direction for a few hundred millivolts. An extension of the linear region defines i.... at the
intersection with Eoor,.The corrosion rate R.... in milli-inches per year (MPY) can be obtained from
the following equation:
R.... =0.13i .... EW/d
Here, i.... is the corrosion current density (#A-cm-2), EW is the equivalent weight of copper, and d is
its density. Further corrosion measurement details have been given elsewhere [12-14].
The UV/Vis spectra were recorded with a UV-160 A Shimadzu spectrophotometer. The cyclic
voltammograms were recorded using the polarographic analyzer Model 264A and the electrode
assembly (303A) of 2.6 x 10-2 cm2 area with a sweep rate of 20 mV"sec-1.
The synthesis of the investigated azo-heterocyclic dyes of the type 3-arylazo 1,2,4 triazole
compounds was accomplished directly via the coupling reaction of the diazonim salt of 3-amino
1,2,4-triazole with different types of phenolic compounds.
The investigated arylazatriazole dyes were:
GHO
N--~1~N:N~~ OH
~.N/N
I
H
3-(3-formyl-4-hydroxg- l-phenylazo)- l ,2,4-triazole (D1)
HO
N7-N=N-LNN
I
H
3-(2-hydroxy-5-methyl- l -phenylazo )-l ,2,4-triazole (D2)
9. Inhibition of Copper Corrosion 1095
N ,[--N:N-~OH
II i~
L..N/N
I
H
3-(4-hydroxy-l-phenylazo)-l,2,4-triazole (/:)3)
References
[1] Mansfeld F, Smith T, Parry EP (1971) corrosion 27:289
[2] Poling GW (1970) Corros Sci 10:359
[3] Fox PG, Lewis G, Bonden PJ (1979) Corros Sci 19:457
[4] Hollander O, May PC (1985) Corros Nace 41:39
[5] Zichuman G, Tong R, Notoya T (1991) B Electrochem 7:60
[6] Gaber M, Hassanein M, Ahmed HA (1986) Indian J Textile Res ll: 48
[7] Chadwick D, Hashemi T (1978) Corros Sci 18:39
[8] Faita G, Fiori G, Salvadore D (1975) Corros Sci 15:383
[9] Dahar HP, White RE, Burnell G, Cornwell LR, Griffin RB, Darby R (1985)Corros Nace 41:317
[10] Parhetier; Souchay "Chemical Kinetics". Elsevier, New York (1967): 155
[11] Taqui Khan MM, Shukla RS (1991) Polyhedron 10:2711
[123 Elmorsi MA, Mabrouk EM, Issa RM, Ghoneim MM (1987) Surface Coatings Technol 30:277
[13] Elmorsi MA, Ghoneim MM, Issa FM, Mabrouk EM (1987) Surface Coatings Technol 31:389
[14] Elmorsi MA, El-Sheikh MY, Bastawessy AM, Ghoneim MM (1991) B Electrochem 7:158
Received January 10, I995. Accepted (revised) April 24, 1995