No description available.

No / Extracting waterborne contaminants to ozone-loaded Volasil¿245 (a siloxane solvent in which ozone is ten times more soluble than water) has been studied as a means of enhancing reaction kinetics and thus, providing more rapid wastewater decontamination. Investigation was carried out with respect to 2-chlorophenol and dichloromethane. Using a pilot scale continuous flow liquid¿liquid/ozone water treatment system, 2-chlorophenol was extracted to the ozone-loaded solvent phase and considerable extents of destruction were achieved. However, the approach was demonstrated to yield slightly less destruction than direct gas contact for the same utilization of ozone and enhanced reaction kinetics were not shown to occur. This was suggested to be due to increased interfacial mass transfer resistance and/or the promotion of less destructive reaction pathways. Modification of the existing pilot system, by conversion from co- to counter-current solvent-loading, enabled greater dissolved ozone concentrations to be achieved within the solvent. Increasing the counter-current exchange column height to not, vert, similar2.5 m was suggested for achieving a near optimum level of performance. The liquid¿liquid/ozone approach was demonstrated to be an effective means of indirectly exposing wastewater contaminants to concentrated ozone. As such the technology may be applicable as an alternative to direct gas contact in instances where the avoidance of contaminant sparging is desired (i.e. where contaminants are highly volatile, pungent and/or toxic) or foaming occurs

M.S.

Die Effektivität der Reaktivextraktion als Verfahren zur Stoffabtrennung aus wässrigen Lösungen mit organischen Lösungsmitteln lässt sich durch den Zusatz weiterer Stoffe deutlich steigern. Das können Co-Ionen, Lösungsvermittler und Stoffe sein, die die Phasengrenzfläche beeinflussen. Wichtigste Vertreter der letzteren Gruppe sind Tenside, die die Grenzflächenspannung zwischen den Phasen verringern. Sie werden in der industriellen Technik bereits seit Jahrzehnten mit gleich bleibendem Erfolg angewandt. Dabei sind die Vorgänge an der Phasengrenze, die durch die Tenside beeinflusst werden, noch nicht vollständig geklärt. In diesem Umfeld ist auch die vorliegende Arbeit entstanden. Sie soll bereits am Lehrstuhl vorliegende Arbeiten ergänzen. Gegenstand der Untersuchungen ist der Einfluss von Tensiden auf die Extraktion von Schwermetallionen im elektrischen Feld, hier untersucht an dem kationischen Tensid Hexadecyltrimethylammoniumbromid (CTAB). Als Untersuchungsmethode wird die Polarographie verwendet. Der Ladungsdurchtritt durch die Grenzfläche Wasser/Quecksilber und deren Beeinflussung durch das Tensid werden für die Metallionen von Zink, Cadmium, Blei und Chrom bei unterschiedlichen pH-Werten untersucht. Es zeigt sich, dass die Modifizierung der Grenzfläche nur einen Teil der Beeinflussung ausmacht, weitere entstehen durch die chemische Modifizierung der vorhandenen Spezies. Weiterhin kann abgeleitet werden, dass trotz chemischer Verwandtschaft der eingesetzten Systeme eine klare Vorhersage der Beeinflussung nur begrenzt möglich ist. Der grundlegende Trend von Systemen mit chemisch ähnlicher Zusammensetzung ist zwar der gleiche, jedes System reagiert jedoch individuell in Abhängigkeit der genauen stofflichen Zusammensetzung und der Versuchsbedingungen, so dass stets konkrete Voruntersuchungen notwendig erscheinen.

Orientadores: Maria Regina Wolf Maciel, Antonio Jose de Almeida Meirelles / Tese (doutorado) - Universidade Estadual de Campinas, Faculdade de Engenharia Quimica / Made available in DSpace on 2018-08-11T14:05:30Z (GMT). No. of bitstreams: 1 Gitirana_LucianaLintomen_D.pdf: 2222416 bytes, checksum: a70434bb137c8a74550f9b83da7277f0 (MD5) Previous issue date: 2007 / Resumo: Esse estudo objetiva uma avaliação crítica do processo de extração líquido-líquido de ácidos orgânicos, produzidos principalmente por fermentação. Os ácidos orgânicos de interesse nesse trabalho são: ácido cítrico, ácido málico, ácido succínico e ácido tartárico. O estudo engloba, de uma forma geral, a recuperação e a purificação dos ácidos orgânicos selecionados e, para esse propósito, envolve a caracterização termodinâmica dos sistemas envolvidos, a modelagem termodinâmica e a simulação do processo de extração líquidolíquido. Os dados de equilíbrio líquido-líquido foram obtidos a 25oC, e os alcoóis, 2- Butanol e n- Butanol foram avaliados como extratantes, considerando os sistemas ternários e os quaternários, com o efeito ¿salting out¿, onde o sal MgCl2 foi adicionado. A Modelagem Termodinâmica do equilíbrio líquido-líquido, através do Método de Contribuição de Grupos (UNIFAC-Larsen) e da Modelagem Molecular (NRTL e NRTL Eletrolítico), foi realizada em alguns casos considerando a presença de eletrólitos fortes provenientes da dissociação do sal nos sistemas quaternários, com efeito, ¿salting out¿ / Abstract: This study aims a critical evaluation of the liquid-liquid extraction process of organic acids, produced by fermentation. The organic acids of interest in this work are: citric acid, malic acid, succinic acid and tartaric acid. The study includes the recovery and the purification of the chosen organic acids, the thermodynamic characterization of the systems, thermodynamic modelling and simulation of the liquid-liquid extraction process. The liquid-liquid equilibrium data were obtained at 25oC, and the alcohols, 2-Butanol and n-Butanol were evaluated as extractants, considering the ternary systems and quaternary systems with salting out effect, where the salt MgCl2 was added. The Thermodynamic Modelling of the liquid-liquid equilibrium data, though the group contribution Method (UNIFAC-Larsen) and though Molecular Modelling (NRTL and the so-called electrolytic NRTL), was carried out in some cases considering the presence of strong electrolytes from the salt dissociation in the quaternary systems with salting out effect / Doutorado / Desenvolvimento de Processos Químicos / Doutor em Engenharia Química

Die Effektivität der Reaktivextraktion als Verfahren zur Stoffabtrennung aus wässrigen Lösungen mit organischen Lösungsmitteln lässt sich durch den Zusatz weiterer Stoffe deutlich steigern. Das können Co-Ionen, Lösungsvermittler und Stoffe sein, die die Phasengrenzfläche beeinflussen. Wichtigste Vertreter der letzteren Gruppe sind Tenside, die die Grenzflächenspannung zwischen den Phasen verringern. Sie werden in der industriellen Technik bereits seit Jahrzehnten mit gleich bleibendem Erfolg angewandt. Dabei sind die Vorgänge an der Phasengrenze, die durch die Tenside beeinflusst werden, noch nicht vollständig geklärt. In diesem Umfeld ist auch die vorliegende Arbeit entstanden. Sie soll bereits am Lehrstuhl vorliegende Arbeiten ergänzen. Gegenstand der Untersuchungen ist der Einfluss von Tensiden auf die Extraktion von Schwermetallionen im elektrischen Feld, hier untersucht an dem kationischen Tensid Hexadecyltrimethylammoniumbromid (CTAB). Als Untersuchungsmethode wird die Polarographie verwendet. Der Ladungsdurchtritt durch die Grenzfläche Wasser/Quecksilber und deren Beeinflussung durch das Tensid werden für die Metallionen von Zink, Cadmium, Blei und Chrom bei unterschiedlichen pH-Werten untersucht. Es zeigt sich, dass die Modifizierung der Grenzfläche nur einen Teil der Beeinflussung ausmacht, weitere entstehen durch die chemische Modifizierung der vorhandenen Spezies. Weiterhin kann abgeleitet werden, dass trotz chemischer Verwandtschaft der eingesetzten Systeme eine klare Vorhersage der Beeinflussung nur begrenzt möglich ist. Der grundlegende Trend von Systemen mit chemisch ähnlicher Zusammensetzung ist zwar der gleiche, jedes System reagiert jedoch individuell in Abhängigkeit der genauen stofflichen Zusammensetzung und der Versuchsbedingungen, so dass stets konkrete Voruntersuchungen notwendig erscheinen.

The submitted thesis is focused on the development, optimization, testing and practical application of the new microextraction method called Bell Shaped Extraction Device assisted Liquid-Liquid Microextraction (BSED-LLME). The method is based on the application of a miniature bell-shaped extraction tool in which the extraction takes place, so that only minimal solvent losses can occur, and which allows a reproducible dosing and collection of a small volume of the extraction solvent. The BSED- LLME method was used to preconcentrate selected volatile and less volatile analytes from aqueous samples into organic solvents of a density lower than water. After the extraction, the analytes were determined by fast gas chromatography with flame ionization detection and gas chromatography with mass spectrometry. The statistical methods known as Design of Experiment (DOE) were used for determination of the optimal extraction conditions for BSED-LLME procedure. DOE is based on a mathematical description of the system and the prediction of the optimal setting of experimental parameters that may influence extraction efficiency. Factors such as extraction time, volume of extraction solvent, addition of sodium chloride (ionic strength), stirring rate and the diameter of the extraction vessel ect., have been tested....

Submitted in fulfilment of the requirements of the Masters Degree in Technology: Chemistry, Durban University of Technology, 2012. / The thesis involves a study of the thermodynamics of ternary liquid mixtures involving carboxylic acids with sulfolane, hydrocarbons and acetonitrile. Carboxylic acids are an important group of polar compounds with many industrial and commercial uses and applications. In South Africa, these carboxylic acids together with many other oxygenates and hydrocarbons are manufactured by SASOL using the Fischer–Tropsch process. The separation of these acids from hydrocarbons is a commercially viable option, and is an important reason for this study. This work focuses on the use of sulfolane in effecting separation by solvent extraction and not by the more common and energy intensive method of distillation. Sulfolane was chosen because of its high polarity and good solvent extraction properties. The first part of this study involves the determination of excess molar volumes (VmE) of binary mixtures of sulfolane (1) + carboxylic acids (2) at different temperatures of 303.15 K and 308.15 K, where carboxylic acids refer to acetic acid, propanoic acid, butanoic acid, 2-methylpropanoic acid, pentanoic acid and 3-methylbutanoic acid respectively. The densities of the binary systems of sulfolane (1) + carboxylic acids (2) were measured at T = 303.15 K and 308.15 K. The excess molar volumes were calculated from the experimental densities at each temperature. The VmE were negative for the entire mole fractions for all the binary systems. It was found that the VmE in the systems studied increase with an increase in temperature, and also VmE decreases with an increase in the carbon chain length of the carboxylic acid. The VmE data results were correlated using Redlich-Kister equation. Abstract ii The second part was the study of the binodal or solubility curves and tie line data for the ternary systems of [sulfolane (1) + carboxylic acids (2) + hydrocarbons (3)] and [acetonitrile (1) + carboxylic acids (2) + hydrocarbon (3)]. Hydrocarbons refer to pentane, hexane, dodecane and hexadecane. The binodal curve experimental data was determined by the cloud point technique. Liquid-liquid equilibrium (LLE) phase diagrams were constructed using the mole fractions and refractive indices (nD). Tie line data were obtained for the sulfolane-rich and hydrocarbon-rich phases as well as the acetonitrile-rich and hydrocarbon-rich phases respectively. The tie lines in both cases were skewed towards the hydrocarbon-rich phases indicating that relative mutual solubility of carboxylic acids is higher in the hydrocarbon-rich phase than in the solvent-rich phase. Selectivity values were calculated from the tie-lines to determine the extraction capabilities of solvents sulfolane and acetonitrile. Selectivity values in all cases were greater than one, meaning that both sulfolane and acetonitrile can be used to separate carboxylic acids from hydrocarbons. Binodal curve data were correlated by the Hlavatý, beta (𝛽) and log𝛾 equations; average standard deviation error for Hlavatý was 0.012, for beta (𝛽), 0.023 and for log𝛾, 0.021. The NRTL and UNIQUAC models were used to correlate the experimental tie-lines. The calculated values based on the NRTL equation were found to be better than those based on UNIQUAC equation; the average root-mean square deviation, (rmsd), between the phase composition obtained from experiment and that from calculation was 0.061 for the NRTL model, as compared to 0.358 for UNIQUAC model for the ternary systems involving sulfolane. For ternary systems of acetonitrile, the NRTL equation was better than the UNIQUAC with the rsmd of 0.003 and 0.287for UNIQUAC equation. / DUT Postgraduate Development and Support Directorate (PGDS)

Submitted in fulfilment of the academic requirements for the Masters Degree in Technology: Chemistry, Durban University of Technology, 2012. / In this work, the thermodynamics of ternary liquid mixtures involving carboxylic acids with sulfolane, hydrocarbons including cycloalkane, and alcohols are presented. In South Africa, Sasol is one of the leading companies that produce synthesis gas from low grade coal. Carboxylic acids together with many other oxygenate and hydrocarbons are produced by Sasol using the Fischer-Tropsch process. Carboxylic acids class is one of the important classes of compounds with great number of industrial uses and applications. The efficient separation of carboxylic acids from hydrocarbons and alcohols from hydrocarbons is of economic importance in the chemical industry, and many solvents have been tried and tested to improve such recovery. This work focussed on the use of the polar solvent sulfolane in the effective separation by solvent extraction and not by more common energy intensive method of distillation. The first part of the experimental work focussed on ternary liquid-liquid equilibria of mixtures of [sulfolane (1) + carboxylic acid (2) + heptane (3) or cyclohexane or dodecane] at T = 303.15 K, [sulfolane (1) + alcohol (2) + heptane (3)] at T = 303.15 K. Carboxylic acid refers to acetic acid, propanoic acid, butanoic acid, 2-methylpropanoic acid, pentanoic acid and 3-methylbutanoic acid. Alcohol refers to methanol, ethanol, 1- propanol, 2-propanol, 1-butanol, 2-butanol, 2-methyl-1-propanol and 2-methyl-2-propanol. Ternary liquid- liquid equilibrium data are essential for the design and selection of solvents used from liquid- liquid extraction process. Abstract vi The separation of carboxylic acids from hydrocarbons and the alcohols from hydrocarbons is commercially lucrative consideration and is an important reason of this study. The separation of carboxylic acids or alcohols from hydrocarbons by extraction with sulfolane was found to be feasible as all selectivity values obtained are greater than 1. The modified Hlavatý, beta (β) and log equations were fitted to the experimental binodal data measured in this work. Hlavatý gave the best overall fit as compared to beta ( ) and log function. The NRTL (Non-Random, Two Liquid) and UNIQUAC Universal Quasichemical) model were used to correlate the experimental tie-lines and calculate the phase compositions of the ternary systems. The correlation work served three purposes:  to summarise experimental data  to test theories of liquid mixtures  prediction of related thermodynamics properties. The final part of the study was devoted to the determination of the excess molar volumes of mixtures of [sulfolane (1) + alcohol (2)] at T = 298.15 K, T = 303.15 K and T = 309.15 K. Density was used to determine the excess molar volumes of the mixtures of [sulfolane (1) + alcohols (2)]. Alcohol refers to methanol, ethanol, 1- propanol, 2-propanol, 1-butanol, 2-butanol, 2-methyl-1-propanol, 2-methyl-2-propanol. The work was done to investigate the effect of temperature on excess molar volumes of binary mixtures of alcohols and sulfolane, as well as to get some idea of interactions involved between an alcohol and sulfolane. The excess molar volume data for each binary mixture was fitted in the Redlich–Kister equation to correlate the composition dependence of the excess property. / National Research Foundation

Submitted in fulfilment of the academic requirements for the Masters Degree in Technology: Chemistry, Durban University of Technology, 2012. / National Research Foundation