Aromatic compounds and ester polymeric solvents interactions
- Authors: Muzenda, Edison
- Date: 2014
- Subjects: Activity coefficients , Aromatic compounds , Esters , Solubility , Volatile organic compounds
- Type: Article
- Identifier: uj:4771 , ISSN 2320–4087 , http://hdl.handle.net/10210/11946
- Description: This work focused on the interactions that occur between ester polymeric solvents and simple aromatic volatile organic compounds (VOCs). Solutes were selected from various functional groups in their simplest form and computations of infinite dilution activity coefficients were performed using the Modified UNIFAC Dortmund group contribution model using a Microsoft Excel spreadsheet designed for this purpose. For polar aromatic VOCs, solubility decreased with increase in size of the ester solvent molecule and the opposite behavior was observed for non-polar VOCs. For all aromatic - ester solvent interactions, solubility increased with the increase in the degree of ester unsaturation.
- Full Text:
- Authors: Muzenda, Edison
- Date: 2014
- Subjects: Activity coefficients , Aromatic compounds , Esters , Solubility , Volatile organic compounds
- Type: Article
- Identifier: uj:4771 , ISSN 2320–4087 , http://hdl.handle.net/10210/11946
- Description: This work focused on the interactions that occur between ester polymeric solvents and simple aromatic volatile organic compounds (VOCs). Solutes were selected from various functional groups in their simplest form and computations of infinite dilution activity coefficients were performed using the Modified UNIFAC Dortmund group contribution model using a Microsoft Excel spreadsheet designed for this purpose. For polar aromatic VOCs, solubility decreased with increase in size of the ester solvent molecule and the opposite behavior was observed for non-polar VOCs. For all aromatic - ester solvent interactions, solubility increased with the increase in the degree of ester unsaturation.
- Full Text:
Influence of temperature and intermolecular forces on volatile organic compounds-ester interactions
- Authors: Scheepers, Jacques Johan
- Date: 2014-06-04
- Subjects: Volatile organic compounds , Volatile organic compounds - Environmental aspects
- Type: Thesis
- Identifier: uj:11392 , http://hdl.handle.net/10210/11030
- Description: M.Tech. (Chemical Engineering) , Increasing pressure on industry from national and international communities for more environmentally friendly operations has generated a drive towards the use of ‘green’ absorbents in the removal of volatile organic compounds from contaminated air streams. The objective of this work was to investigate the use of ester solvents, especially biodiesel esters, as suitable ‘green’ scrubbing solvents for the absorption of volatile organic compounds (VOCs) from gaseous waste streams. The objective was accomplished by investigating the nature of molecular interactions between ester solvents and various families of VOC solvents, and by studying the effect of temperature on absorption, through the analysis of infinite dilution activity coefficients. Activity coefficients were computed with a Microsoft Excel generated spread sheet using Modified UNIFAC Dortmund (1987) as a thermodynamic predictive model. Results show that non-polar solutes are more soluble in long chain ester solvents whilst polar solutes absorb easier in short chain ester solvents. The solubility of non-polar solutes decreases with increasing ester solvent unsaturation, whilst the opposite is true for polar solutes in esters. Short chain length non-polar solutes are more soluble than long chain length non-polar solutes in ester solvents, whilst the opposite trend occurs for polar solutes in ester solvents. An increase in branching of polar solutes results in the solute behaving more like a non-polar solute. Unfortunately UNIFAC models fail to account for functional group proximity effects, which may result in inaccurate results for systems involving highly branched solutes. However given that the purpose of this study was only to establish trends for generating an understanding of molecular interactions between the solutes and the solvent, it was acceptable to assume that these inaccuracies would be minor for the intended purpose. It was found that activity coefficients of ester/ solute interactions generally tend towards ideality with increasing temperature with the exception of alkanes and the nitrogen based VOCs, as well as tetrahydrofuran and tetrahydropyran, methacrolein and organic acid/ unsaturated ester interactions. In the case of the alkanes, tetrahydrofuran and tetrahydropyran, high-temperature absorption is preferred whilst for methacrolein lower temperature absorption is preferred. It was concluded that ester solvents ,especially biodiesel esters, are well suited for the removal of non-polar to moderately polar VOC solutes from waste gas streams due to the favourably low activity coefficients obtained for these ester/ solute interactions. The results presented in this report are comprehensive and can assist in making informed decisions in using biodiesel as a scrubbing solvent.
- Full Text:
- Authors: Scheepers, Jacques Johan
- Date: 2014-06-04
- Subjects: Volatile organic compounds , Volatile organic compounds - Environmental aspects
- Type: Thesis
- Identifier: uj:11392 , http://hdl.handle.net/10210/11030
- Description: M.Tech. (Chemical Engineering) , Increasing pressure on industry from national and international communities for more environmentally friendly operations has generated a drive towards the use of ‘green’ absorbents in the removal of volatile organic compounds from contaminated air streams. The objective of this work was to investigate the use of ester solvents, especially biodiesel esters, as suitable ‘green’ scrubbing solvents for the absorption of volatile organic compounds (VOCs) from gaseous waste streams. The objective was accomplished by investigating the nature of molecular interactions between ester solvents and various families of VOC solvents, and by studying the effect of temperature on absorption, through the analysis of infinite dilution activity coefficients. Activity coefficients were computed with a Microsoft Excel generated spread sheet using Modified UNIFAC Dortmund (1987) as a thermodynamic predictive model. Results show that non-polar solutes are more soluble in long chain ester solvents whilst polar solutes absorb easier in short chain ester solvents. The solubility of non-polar solutes decreases with increasing ester solvent unsaturation, whilst the opposite is true for polar solutes in esters. Short chain length non-polar solutes are more soluble than long chain length non-polar solutes in ester solvents, whilst the opposite trend occurs for polar solutes in ester solvents. An increase in branching of polar solutes results in the solute behaving more like a non-polar solute. Unfortunately UNIFAC models fail to account for functional group proximity effects, which may result in inaccurate results for systems involving highly branched solutes. However given that the purpose of this study was only to establish trends for generating an understanding of molecular interactions between the solutes and the solvent, it was acceptable to assume that these inaccuracies would be minor for the intended purpose. It was found that activity coefficients of ester/ solute interactions generally tend towards ideality with increasing temperature with the exception of alkanes and the nitrogen based VOCs, as well as tetrahydrofuran and tetrahydropyran, methacrolein and organic acid/ unsaturated ester interactions. In the case of the alkanes, tetrahydrofuran and tetrahydropyran, high-temperature absorption is preferred whilst for methacrolein lower temperature absorption is preferred. It was concluded that ester solvents ,especially biodiesel esters, are well suited for the removal of non-polar to moderately polar VOC solutes from waste gas streams due to the favourably low activity coefficients obtained for these ester/ solute interactions. The results presented in this report are comprehensive and can assist in making informed decisions in using biodiesel as a scrubbing solvent.
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Temperature effect on volatile organic compounds – polydimethylsiloxane Interactions
- Muzenda, Edison, Ntuli, Freeman
- Authors: Muzenda, Edison , Ntuli, Freeman
- Date: 2011
- Subjects: Waste gas streams , Volatile organic compounds , Polydimethysiloxane , Gas liquid chromatography
- Type: Article
- Identifier: uj:2179 , ISSN 2010-0221 , http://hdl.handle.net/10210/4559
- Description: Temperature dependence of specific retention volumes (og V) of 13 volatile organic compounds (VOCs) of environmental importance between the gas and liquid stationary phase (polydimethysiloxane) (PDMS) were studied using the gas liquid chromatographic technique (GLC). Temperature was varied from 303.15K to 423.15K to allow transport calculations for different seasons. Four PDMS polymers with average molecular weight ranging from 760 to 13 000 were used as solvents. The results of this work confirm that PDMS is well suited for VOCs scrubbing from waste gas streams. Linear plots of log g V against T1 were obtained in all cases permitting predictions and interpolations to temperatures not studied here. Also dependable enthalpies and entropies of solute transfer from the mobile phase to the stationary phase can be calculated. The specific retention volumes reported in this work are in agreement with literature for similar systems. Efforts were taken to ensure the best possible accuracy and trace the possible sources of error. A gas liquid chromatographic system which secured a simple retention mechanism and showed reproducible solute retention over a long period of time was devised.
- Full Text:
- Authors: Muzenda, Edison , Ntuli, Freeman
- Date: 2011
- Subjects: Waste gas streams , Volatile organic compounds , Polydimethysiloxane , Gas liquid chromatography
- Type: Article
- Identifier: uj:2179 , ISSN 2010-0221 , http://hdl.handle.net/10210/4559
- Description: Temperature dependence of specific retention volumes (og V) of 13 volatile organic compounds (VOCs) of environmental importance between the gas and liquid stationary phase (polydimethysiloxane) (PDMS) were studied using the gas liquid chromatographic technique (GLC). Temperature was varied from 303.15K to 423.15K to allow transport calculations for different seasons. Four PDMS polymers with average molecular weight ranging from 760 to 13 000 were used as solvents. The results of this work confirm that PDMS is well suited for VOCs scrubbing from waste gas streams. Linear plots of log g V against T1 were obtained in all cases permitting predictions and interpolations to temperatures not studied here. Also dependable enthalpies and entropies of solute transfer from the mobile phase to the stationary phase can be calculated. The specific retention volumes reported in this work are in agreement with literature for similar systems. Efforts were taken to ensure the best possible accuracy and trace the possible sources of error. A gas liquid chromatographic system which secured a simple retention mechanism and showed reproducible solute retention over a long period of time was devised.
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Volatile organic compounds – biphenyl thermodynamic interactions
- Authors: Muzenda, Edison
- Date: 2014
- Subjects: Absorption , Activity coefficient , Phase equilibrium , Volatile organic compounds , Thermodynamics
- Type: Article
- Identifier: uj:4989 , ISSN 2078-0966 , http://hdl.handle.net/10210/13124
- Description: This work focused on the thermodynamic interactions involving volatile organic compounds (VOCs) and biphenyl. The solubility of 60 VOCs in biphenyl was studied using group contribution methods. The modified UNIFAC Dortmund and Lyngby were used to compute the required phase equilibrium in the form of infinite dilution activity coefficients. Six family groups were studied mainly alkanes, alkenes, alkynes, aldehydes, alcohols, and carboxylic acids. The Modified UNIFAC Dortmund performed better than the Modified UNIFAC Lyngby. Biphenyl showed excellent absorption affinity for all VOCs in particular for alkynes and aldehydes. The solubility decreased with increase in VOC molecular weight.
- Full Text:
- Authors: Muzenda, Edison
- Date: 2014
- Subjects: Absorption , Activity coefficient , Phase equilibrium , Volatile organic compounds , Thermodynamics
- Type: Article
- Identifier: uj:4989 , ISSN 2078-0966 , http://hdl.handle.net/10210/13124
- Description: This work focused on the thermodynamic interactions involving volatile organic compounds (VOCs) and biphenyl. The solubility of 60 VOCs in biphenyl was studied using group contribution methods. The modified UNIFAC Dortmund and Lyngby were used to compute the required phase equilibrium in the form of infinite dilution activity coefficients. Six family groups were studied mainly alkanes, alkenes, alkynes, aldehydes, alcohols, and carboxylic acids. The Modified UNIFAC Dortmund performed better than the Modified UNIFAC Lyngby. Biphenyl showed excellent absorption affinity for all VOCs in particular for alkynes and aldehydes. The solubility decreased with increase in VOC molecular weight.
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Influence of structure on fatty acid ester-alkane interactions
- Scheepers, Jacques J., Muzenda, Edison, Belaid, Mohamed
- Authors: Scheepers, Jacques J. , Muzenda, Edison , Belaid, Mohamed
- Date: 2012
- Subjects: Absorption , Activity coefficients , Biodiesel , Esters , Volatile organic compounds
- Type: Article
- Identifier: uj:4671 , ISSN 978-988-19252-2-0 , http://hdl.handle.net/10210/10436
- Description: The activity coefficients of alkane structures in various types of fatty acid ester solvents was measured in order to determine the effect of bond interactions between these two chemical species. It is important to understand the mechanics of these interactions for absorber system design. Activity coefficients were determined by use of a Microsoft Excel spreadsheet designed for this purpose. It was determined that the length of the ester chain, as well as ester chain saturation had an impact on activity coefficients, in that saturated ester chains and longer ester chains yielded lower activity coefficients. Multiple branched cycloalkanes yielded lower activity coefficients than straight chain hydrocarbons and unbranched cycloalkanes. It was also noted that the location of the carboxyl group in the ester chain had no influence on activity coefficients.
- Full Text:
- Authors: Scheepers, Jacques J. , Muzenda, Edison , Belaid, Mohamed
- Date: 2012
- Subjects: Absorption , Activity coefficients , Biodiesel , Esters , Volatile organic compounds
- Type: Article
- Identifier: uj:4671 , ISSN 978-988-19252-2-0 , http://hdl.handle.net/10210/10436
- Description: The activity coefficients of alkane structures in various types of fatty acid ester solvents was measured in order to determine the effect of bond interactions between these two chemical species. It is important to understand the mechanics of these interactions for absorber system design. Activity coefficients were determined by use of a Microsoft Excel spreadsheet designed for this purpose. It was determined that the length of the ester chain, as well as ester chain saturation had an impact on activity coefficients, in that saturated ester chains and longer ester chains yielded lower activity coefficients. Multiple branched cycloalkanes yielded lower activity coefficients than straight chain hydrocarbons and unbranched cycloalkanes. It was also noted that the location of the carboxyl group in the ester chain had no influence on activity coefficients.
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Volatile organic compounds abatement : a critical discussion of destruction techniques
- Muzenda, Edison, Belaid, Mohamed
- Authors: Muzenda, Edison , Belaid, Mohamed
- Date: 2013
- Subjects: Volatile organic compounds , Bioreactors
- Type: Article
- Identifier: uj:4968 , http://hdl.handle.net/10210/13069
- Description: This paper critically discusses volatile organic compounds destruction techniques. The methods discussed are thermal and recuperative oxidation, catalytic oxidation, regenerative oxidation, flares and bioreactors. Examples of bioreactors discussed are bio-filters, bio-trickling filters and bio-scrubbing filters. The principle of operation as well as the strength and weaknesses of each methods are given.
- Full Text:
- Authors: Muzenda, Edison , Belaid, Mohamed
- Date: 2013
- Subjects: Volatile organic compounds , Bioreactors
- Type: Article
- Identifier: uj:4968 , http://hdl.handle.net/10210/13069
- Description: This paper critically discusses volatile organic compounds destruction techniques. The methods discussed are thermal and recuperative oxidation, catalytic oxidation, regenerative oxidation, flares and bioreactors. Examples of bioreactors discussed are bio-filters, bio-trickling filters and bio-scrubbing filters. The principle of operation as well as the strength and weaknesses of each methods are given.
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Indium-zinc oxide nanostructure materials based sensors for the detection of volatile organic compounds and carbon monoxide
- Authors: Kortidis, Ioannis
- Date: 2019
- Subjects: Volatile organic compounds , Nanostructured materials , Indium , Zinc oxide , Gas detectors
- Language: English
- Type: Doctoral (Thesis)
- Identifier: http://hdl.handle.net/10210/292586 , uj:31798
- Description: Abstract: Detection of poisonous and flammable gases for health and security purpose utilizing semiconductor metal oxides (SMO) based sensors has fascinated ample attention owing to their incomparable advantages, such as a flawless evidence in variation of their sensor resistance when exposed to either reducing or oxidizing gases. Moreover, their rapid response and recovery times as well as their remarkable sensitivity make them appealing. It is well-known that an anticipated gas sensor ought to possess a combination of enhanced sensitivity, excellent selectivity, rapid response-recovery times, long-term stability and low working temperature. These factors are mostly reliant on surface area to volume ratio, higher relative concentration of defects and crystal structure of the SMO sensing layer. Moreover, this work is justified by the demand of gas sensors globally, with the market estimated to reach approximately R38.4-billion by 2020. According to World Health Organization (WHO) and World Bank, about 5.5 million deaths happen annually costing the world economy R70-trillion a year due to air pollution. While in South Africa about 20 000 deaths occur every year, costing the economy nearly R300-million due to air pollution. Recently, WHO has indicated that most of the cities in SA (such as Pretoria, Johannesburg, etc.) exceed the limit of air quality (AQ) with roughly five times the WHO recommendation, while over 90% of the world's population live in areas that exceed WHO limits on air pollution... , Ph.D. (Chemistry)
- Full Text:
- Authors: Kortidis, Ioannis
- Date: 2019
- Subjects: Volatile organic compounds , Nanostructured materials , Indium , Zinc oxide , Gas detectors
- Language: English
- Type: Doctoral (Thesis)
- Identifier: http://hdl.handle.net/10210/292586 , uj:31798
- Description: Abstract: Detection of poisonous and flammable gases for health and security purpose utilizing semiconductor metal oxides (SMO) based sensors has fascinated ample attention owing to their incomparable advantages, such as a flawless evidence in variation of their sensor resistance when exposed to either reducing or oxidizing gases. Moreover, their rapid response and recovery times as well as their remarkable sensitivity make them appealing. It is well-known that an anticipated gas sensor ought to possess a combination of enhanced sensitivity, excellent selectivity, rapid response-recovery times, long-term stability and low working temperature. These factors are mostly reliant on surface area to volume ratio, higher relative concentration of defects and crystal structure of the SMO sensing layer. Moreover, this work is justified by the demand of gas sensors globally, with the market estimated to reach approximately R38.4-billion by 2020. According to World Health Organization (WHO) and World Bank, about 5.5 million deaths happen annually costing the world economy R70-trillion a year due to air pollution. While in South Africa about 20 000 deaths occur every year, costing the economy nearly R300-million due to air pollution. Recently, WHO has indicated that most of the cities in SA (such as Pretoria, Johannesburg, etc.) exceed the limit of air quality (AQ) with roughly five times the WHO recommendation, while over 90% of the world's population live in areas that exceed WHO limits on air pollution... , Ph.D. (Chemistry)
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A comparative study of volatile organic compounds abatement
- Muzenda, Edison, Belaid, Mohamed
- Authors: Muzenda, Edison , Belaid, Mohamed
- Date: 2014
- Subjects: Volatile organic compounds
- Type: Article
- Identifier: uj:5026 , http://hdl.handle.net/10210/13545
- Description: Please refer to full text to view abstract
- Full Text: false
- Authors: Muzenda, Edison , Belaid, Mohamed
- Date: 2014
- Subjects: Volatile organic compounds
- Type: Article
- Identifier: uj:5026 , http://hdl.handle.net/10210/13545
- Description: Please refer to full text to view abstract
- Full Text: false
Interactions of polar and nonpolar volatile organic compounds with methyl ester solvents
- Authors: Muzenda, Edison
- Date: 2013
- Subjects: Activity coefficients , Esters , Solubility , Volatile organic compounds , Methyl ester solvents
- Type: Article
- Identifier: uj:4890 , http://hdl.handle.net/10210/12604
- Description: The interactions of polar and nonpolar volatile organic compounds (VOC) with methyl ester solvents were studied. In order to establish trends two polar and two nonpolar solutes were selected for the study. Solubility computations were performed using the Modified UNIFAC Dortmund group contribution model using a Microsoft Excel spreadsheet. It was found that the solubility of nonpolar solutes in methyl esters increases with an increase in ester chain length, but decreases with an increase in the solute chain length. Furthermore the solubility of nonpolar solutes decreases with an increase in the degree of ester solvent unsaturation. In contrast the solubility of polar solutes in methyl esters decreases with an increase in solvent chain length and increases with increasing solute chain length. Solubility of polar solutes also improved with an increase in the degree of solvent unsaturation. An increase in branching on polar solutes results in an increasing trend towards nonpolar behavior due to the shielding effect of the branches on interactions with the polar site of the solute.
- Full Text:
- Authors: Muzenda, Edison
- Date: 2013
- Subjects: Activity coefficients , Esters , Solubility , Volatile organic compounds , Methyl ester solvents
- Type: Article
- Identifier: uj:4890 , http://hdl.handle.net/10210/12604
- Description: The interactions of polar and nonpolar volatile organic compounds (VOC) with methyl ester solvents were studied. In order to establish trends two polar and two nonpolar solutes were selected for the study. Solubility computations were performed using the Modified UNIFAC Dortmund group contribution model using a Microsoft Excel spreadsheet. It was found that the solubility of nonpolar solutes in methyl esters increases with an increase in ester chain length, but decreases with an increase in the solute chain length. Furthermore the solubility of nonpolar solutes decreases with an increase in the degree of ester solvent unsaturation. In contrast the solubility of polar solutes in methyl esters decreases with an increase in solvent chain length and increases with increasing solute chain length. Solubility of polar solutes also improved with an increase in the degree of solvent unsaturation. An increase in branching on polar solutes results in an increasing trend towards nonpolar behavior due to the shielding effect of the branches on interactions with the polar site of the solute.
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Estimating the absorption of volatile organic compounds in four biodiesels using the Unifac procedure
- Mateescu, Corina M., Muzenda, Edison, Belaid, Mohamed, Abdulkareem, Saka, Afolabi, Ayo S.
- Authors: Mateescu, Corina M. , Muzenda, Edison , Belaid, Mohamed , Abdulkareem, Saka , Afolabi, Ayo S.
- Date: 2011
- Subjects: Biodiesel , Volatile organic compounds , Absorption
- Type: Article
- Identifier: http://ujcontent.uj.ac.za8080/10210/363185 , uj:4696 , http://hdl.handle.net/10210/10760
- Description: This work considered the thermodynamic feasibility of scrubbing volatile organic compounds into biodiesel in view of designing a gas treatment process with this absorbent. A detailed vapour – liquid equilibrium investigation was performed using the original UNIFAC group contribution method. The four biodiesels studied in this work are methyl oleate, methyl palmitate, methyl linolenate and ethyl stearate. The original UNIFAC procedure was used to estimate the infinite dilution activity coefficients of 13 selected volatile organic compounds in the biodiesels. The calculations were done at the VOC mole fraction of 9.213x10-8. Ethyl stearate gave the most favourable phase equilibrium. A close agreement was found between the infinite dilution activity coefficient of toluene found in this work and those reported in literature. Thermodynamic models can efficiently be used to calculate vast amount of phase equilibrium behaviour using limited number of experimental data.
- Full Text:
- Authors: Mateescu, Corina M. , Muzenda, Edison , Belaid, Mohamed , Abdulkareem, Saka , Afolabi, Ayo S.
- Date: 2011
- Subjects: Biodiesel , Volatile organic compounds , Absorption
- Type: Article
- Identifier: http://ujcontent.uj.ac.za8080/10210/363185 , uj:4696 , http://hdl.handle.net/10210/10760
- Description: This work considered the thermodynamic feasibility of scrubbing volatile organic compounds into biodiesel in view of designing a gas treatment process with this absorbent. A detailed vapour – liquid equilibrium investigation was performed using the original UNIFAC group contribution method. The four biodiesels studied in this work are methyl oleate, methyl palmitate, methyl linolenate and ethyl stearate. The original UNIFAC procedure was used to estimate the infinite dilution activity coefficients of 13 selected volatile organic compounds in the biodiesels. The calculations were done at the VOC mole fraction of 9.213x10-8. Ethyl stearate gave the most favourable phase equilibrium. A close agreement was found between the infinite dilution activity coefficient of toluene found in this work and those reported in literature. Thermodynamic models can efficiently be used to calculate vast amount of phase equilibrium behaviour using limited number of experimental data.
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Organics – biodiesel systems phase equilibrium computation : part 1
- Nkosi, Nhlanhla P., Mokoena, Phumzile, Muzenda, Edison, Belaid, Mohamed
- Authors: Nkosi, Nhlanhla P. , Mokoena, Phumzile , Muzenda, Edison , Belaid, Mohamed
- Date: 2011
- Subjects: Activity coefficient , Group contribution , Phase equilibrium , Solubility , Volatile organic compounds
- Type: Article
- Identifier: uj:4675 , http://hdl.handle.net/10210/10444
- Description: The group contribution concept can be applied in the estimation of thermodynamic properties of pure compounds and mixtures. The Modified UNIFAC (Dortmund) is a successful and well-known group contribution model for phase equilibria prediction. In this paper the application of this model to the phase equilibrium of biodiesel - volatile organic compounds systems was tested. Infinite dilution activity coefficients of 30 selected volatile organic compounds (VOCs) in methyl linoleate and methyl palmitate were estimated. The VOCs groups covered in the selection were alkanes, alkenes, alkynes, aromatics, ethers and ketones. The estimated phase equilibrium is favourable for the absorption of these organics into methyl linoleate. The solubility was found to decrease with increase in molecular weight of the VOCs in each group. Saturation was also found to have an effect on solubility. Experimental data are often not available, at least for preliminary design and feasibility studies of absorption processes, group contribution methods can be utilized to predict the required phase equilibria.
- Full Text:
- Authors: Nkosi, Nhlanhla P. , Mokoena, Phumzile , Muzenda, Edison , Belaid, Mohamed
- Date: 2011
- Subjects: Activity coefficient , Group contribution , Phase equilibrium , Solubility , Volatile organic compounds
- Type: Article
- Identifier: uj:4675 , http://hdl.handle.net/10210/10444
- Description: The group contribution concept can be applied in the estimation of thermodynamic properties of pure compounds and mixtures. The Modified UNIFAC (Dortmund) is a successful and well-known group contribution model for phase equilibria prediction. In this paper the application of this model to the phase equilibrium of biodiesel - volatile organic compounds systems was tested. Infinite dilution activity coefficients of 30 selected volatile organic compounds (VOCs) in methyl linoleate and methyl palmitate were estimated. The VOCs groups covered in the selection were alkanes, alkenes, alkynes, aromatics, ethers and ketones. The estimated phase equilibrium is favourable for the absorption of these organics into methyl linoleate. The solubility was found to decrease with increase in molecular weight of the VOCs in each group. Saturation was also found to have an effect on solubility. Experimental data are often not available, at least for preliminary design and feasibility studies of absorption processes, group contribution methods can be utilized to predict the required phase equilibria.
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Effect of temperature on specific retention volumes of selected volatile organic compounds using the gas-liquid chromatographic technique revisited
- Muzenda, Edison, Afolabi, Ayo S.
- Authors: Muzenda, Edison , Afolabi, Ayo S.
- Date: 2010
- Subjects: Specific retention volumes , Volatile organic compounds , Polydimethylsiloxane , Gas liquid chromatography
- Type: Article
- Identifier: uj:4711 , http://hdl.handle.net/10210/10957
- Description: This paper is a continuation of our interest in the influence of temperature on specific retention volumes and the resulting infinite dilution activity coefficients. This has a direct effect in the design of absorption and stripping columns for the abatement of volatile organic compounds. The interaction of 13 volatile organic compounds (VOCs) with polydimethylsiloxane (PDMS) at varying temperatures was studied by gas liquid chromatography (GLC). Infinite dilution activity coefficients and specific retention volumes obtained in this study were found to be in agreement with those obtained from static headspace and group contribution methods by the authors as well as literature values for similar systems. Temperature variation also allows for transport calculations for different seasons. The results of this work confirm that PDMS is well suited for the scrubbing of VOCs from waste gas streams.
- Full Text:
- Authors: Muzenda, Edison , Afolabi, Ayo S.
- Date: 2010
- Subjects: Specific retention volumes , Volatile organic compounds , Polydimethylsiloxane , Gas liquid chromatography
- Type: Article
- Identifier: uj:4711 , http://hdl.handle.net/10210/10957
- Description: This paper is a continuation of our interest in the influence of temperature on specific retention volumes and the resulting infinite dilution activity coefficients. This has a direct effect in the design of absorption and stripping columns for the abatement of volatile organic compounds. The interaction of 13 volatile organic compounds (VOCs) with polydimethylsiloxane (PDMS) at varying temperatures was studied by gas liquid chromatography (GLC). Infinite dilution activity coefficients and specific retention volumes obtained in this study were found to be in agreement with those obtained from static headspace and group contribution methods by the authors as well as literature values for similar systems. Temperature variation also allows for transport calculations for different seasons. The results of this work confirm that PDMS is well suited for the scrubbing of VOCs from waste gas streams.
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Solubility of organics in water and silicon oil: a comparative study
- Authors: Muzenda, Edison
- Date: 2011
- Subjects: Volatile organic compounds , Solubility , Water , Silicon oil , Activity coefficients , Henry’s Law constants
- Type: Article
- Identifier: uj:5321 , http://hdl.handle.net/10210/8228
- Description: The aim of this study was to compare the solubility of selected volatile organic compounds in water and silicon oil using the simple static headspace method. The experimental design allowed equilibrium achievement within 30 – 60 minutes. Infinite dilution activity coefficients and Henry’s law constants for various organics representing esters, ketones, alkanes, aromatics, cycloalkanes and amines were measured at 303K. The measurements were reproducible with a relative standard deviation and coefficient of variation of 1.3x10-3 and 1.3 respectively. The static determined activity coefficients using shaker flasks were reasonably comparable to those obtained using the gas liquid - chromatographic technique and those predicted using the group contribution methods mainly the UNIFAC. Silicon oil chemically known as polydimethysiloxane was found to be better absorbent for VOCs than water which quickly becomes saturated. For example the infinite dilution mole fraction based activity coefficients of hexane is 0.503 and 277 000 in silicon oil and water respectively. Thus silicon oil gives a superior factor of 550 696. Henry’s law constants and activity coefficients at infinite dilution play a significant role in the design of scrubbers for abatement of volatile organic compounds from contaminated air streams. This paper presents the phase equilibrium of volatile organic compounds in very dilute aqueous and polymeric solutions indicating the movement and fate of chemical in air and solvent. The successful comparison of the results obtained here and those obtained using other methods by the same authors and in literature, means that the results obtained here are reliable.
- Full Text:
- Authors: Muzenda, Edison
- Date: 2011
- Subjects: Volatile organic compounds , Solubility , Water , Silicon oil , Activity coefficients , Henry’s Law constants
- Type: Article
- Identifier: uj:5321 , http://hdl.handle.net/10210/8228
- Description: The aim of this study was to compare the solubility of selected volatile organic compounds in water and silicon oil using the simple static headspace method. The experimental design allowed equilibrium achievement within 30 – 60 minutes. Infinite dilution activity coefficients and Henry’s law constants for various organics representing esters, ketones, alkanes, aromatics, cycloalkanes and amines were measured at 303K. The measurements were reproducible with a relative standard deviation and coefficient of variation of 1.3x10-3 and 1.3 respectively. The static determined activity coefficients using shaker flasks were reasonably comparable to those obtained using the gas liquid - chromatographic technique and those predicted using the group contribution methods mainly the UNIFAC. Silicon oil chemically known as polydimethysiloxane was found to be better absorbent for VOCs than water which quickly becomes saturated. For example the infinite dilution mole fraction based activity coefficients of hexane is 0.503 and 277 000 in silicon oil and water respectively. Thus silicon oil gives a superior factor of 550 696. Henry’s law constants and activity coefficients at infinite dilution play a significant role in the design of scrubbers for abatement of volatile organic compounds from contaminated air streams. This paper presents the phase equilibrium of volatile organic compounds in very dilute aqueous and polymeric solutions indicating the movement and fate of chemical in air and solvent. The successful comparison of the results obtained here and those obtained using other methods by the same authors and in literature, means that the results obtained here are reliable.
- Full Text:
Volatile organic compounds – polymeric solvents interactions – a thermodynamic computational attempt
- Authors: Muzenda, Edison
- Date: 2014
- Subjects: Phase equilibrium , Solubility , Volatile organic compounds , Normal methyl pyrrolidone
- Type: Article
- Identifier: uj:4770 , ISSN 2320–4087 , http://hdl.handle.net/10210/11945
- Description: This work attempted to model the phase equilibrium involving 50 volatile organic compounds (VOCs) with furfural and normal methyl pyrrolidone (NMP). Polar furfural and dipolar aprotic NMP were tested in this work as potential solvents for the abatement of selected VOCs through physical absorption. Five (5) VOC family groups were studied namely alkanes, alkenes, alcohols, aldehydes and carboxylic groups. The modified UNIFAC Dortmund and Lyngby were used in the phase equilibrium computation. NMP showed better absorption affinity for alkenes, alcohols and carboxylic acids compared to furfural. The solubility decreased with increase in size of the VOCs for both solvents.
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Volatile organic compounds – polymeric solvents interactions – a thermodynamic computational attempt
- Authors: Muzenda, Edison
- Date: 2014
- Subjects: Phase equilibrium , Solubility , Volatile organic compounds , Normal methyl pyrrolidone
- Type: Article
- Identifier: uj:4770 , ISSN 2320–4087 , http://hdl.handle.net/10210/11945
- Description: This work attempted to model the phase equilibrium involving 50 volatile organic compounds (VOCs) with furfural and normal methyl pyrrolidone (NMP). Polar furfural and dipolar aprotic NMP were tested in this work as potential solvents for the abatement of selected VOCs through physical absorption. Five (5) VOC family groups were studied namely alkanes, alkenes, alcohols, aldehydes and carboxylic groups. The modified UNIFAC Dortmund and Lyngby were used in the phase equilibrium computation. NMP showed better absorption affinity for alkenes, alcohols and carboxylic acids compared to furfural. The solubility decreased with increase in size of the VOCs for both solvents.
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Diisononyl phthalate – organics interactions : a phase equilibrium study using modified UNIFAC models
- Pheko, Given T, Muzenda, Edison, Belaid, Mohamed, Mateescu, Corina
- Authors: Pheko, Given T , Muzenda, Edison , Belaid, Mohamed , Mateescu, Corina
- Date: 2013
- Subjects: Phase equilibrium , Volatile organic compounds , Diisononyl phthalate , Absorption abatement
- Type: Article
- Identifier: uj:4857 , http://hdl.handle.net/10210/12533
- Description: Volatile organic compounds (VOCs) are a series of organic compounds that readily vaporize at room temperature. When emitted into the environment can affect climate change and plants growth, and cause long term human health risks. Absorption abatement technique has been the most preferred to reduce VOCs from contaminated gaseous streams, hence the need for a polymeric solvent with a greater affinity for end-pipe inventory. This phase equilibrium study investigated the ability of diisononyl phthalate (DINP) as an absorbent to 80 selected VOCs at infinite dilution. The solvent-solute(s) interactions were studied using modified UNIFAC Lyngby and Dortmund group contribution methods, with the latter being consistent and reliable, as its results are related to literature. Alkanes, alkanes, aldehydes and cyclo-alkanes with shorter carbon-chain length are highly soluble in DINP, with their solubility decreasing with increasing molecular weight or size, at infinite dilution. Alkynes, ketones, alcohols and carboxylic acids are less soluble in DINP, as a result of their dominating polarity compared to the DINP non-polarity structure. However, results could be improved with further studies and publication of solvent-solute(s) sub-groups interaction parameters, and thus further development of modified UNIFAC Lyngby model. DINP is a good absorbent for short-chained non-polar VOCs.
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- Authors: Pheko, Given T , Muzenda, Edison , Belaid, Mohamed , Mateescu, Corina
- Date: 2013
- Subjects: Phase equilibrium , Volatile organic compounds , Diisononyl phthalate , Absorption abatement
- Type: Article
- Identifier: uj:4857 , http://hdl.handle.net/10210/12533
- Description: Volatile organic compounds (VOCs) are a series of organic compounds that readily vaporize at room temperature. When emitted into the environment can affect climate change and plants growth, and cause long term human health risks. Absorption abatement technique has been the most preferred to reduce VOCs from contaminated gaseous streams, hence the need for a polymeric solvent with a greater affinity for end-pipe inventory. This phase equilibrium study investigated the ability of diisononyl phthalate (DINP) as an absorbent to 80 selected VOCs at infinite dilution. The solvent-solute(s) interactions were studied using modified UNIFAC Lyngby and Dortmund group contribution methods, with the latter being consistent and reliable, as its results are related to literature. Alkanes, alkanes, aldehydes and cyclo-alkanes with shorter carbon-chain length are highly soluble in DINP, with their solubility decreasing with increasing molecular weight or size, at infinite dilution. Alkynes, ketones, alcohols and carboxylic acids are less soluble in DINP, as a result of their dominating polarity compared to the DINP non-polarity structure. However, results could be improved with further studies and publication of solvent-solute(s) sub-groups interaction parameters, and thus further development of modified UNIFAC Lyngby model. DINP is a good absorbent for short-chained non-polar VOCs.
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Pre-treatment methods in the abatement of volatile organic compounds : a discussion
- Authors: Muzenda, Edison
- Date: 2012
- Subjects: Abatement , Volatile organic compounds
- Type: Article
- Identifier: uj:6285 , http://hdl.handle.net/10210/9891
- Description: This paper presents a discussion, an analysis, and literature review on the available pre-treatment options for volatile organic compounds (VOCs) prior to abatement. The abatement can be achieved through process and equipment modification, and aid on control techniques. Add on control techniques can be recovery or destructive based such as absorption, adsorption, condensation, membrane separation, and catalytic and thermal oxidation respectively. The pre-treatment methods considered in this paper are dilution, preheating, cooling, particulate removal, dehumidification and liquid knock – out. Pre-treatment is the process of conditioning a volatile organic compound stream and this increase the total cost of the treatment technologies. This paper also highlights the factors governing the selection and application of control technologies.
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- Authors: Muzenda, Edison
- Date: 2012
- Subjects: Abatement , Volatile organic compounds
- Type: Article
- Identifier: uj:6285 , http://hdl.handle.net/10210/9891
- Description: This paper presents a discussion, an analysis, and literature review on the available pre-treatment options for volatile organic compounds (VOCs) prior to abatement. The abatement can be achieved through process and equipment modification, and aid on control techniques. Add on control techniques can be recovery or destructive based such as absorption, adsorption, condensation, membrane separation, and catalytic and thermal oxidation respectively. The pre-treatment methods considered in this paper are dilution, preheating, cooling, particulate removal, dehumidification and liquid knock – out. Pre-treatment is the process of conditioning a volatile organic compound stream and this increase the total cost of the treatment technologies. This paper also highlights the factors governing the selection and application of control technologies.
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A note on the dependence of volatile organic compounds specific retention volumes on temperature
- Muzenda, Edison, Ntuli, Freeman
- Authors: Muzenda, Edison , Ntuli, Freeman
- Date: 2011
- Subjects: Volatile organic compounds , Gas liquid chromatography
- Type: Article
- Identifier: uj:6240 , http://hdl.handle.net/10210/8181
- Description: This study investigated the influence of temperature on the specific retention volumes ( o g V ) of 13 volatile organic compounds (VOCs) in silicon oil as the liquid stationary phase using gas liquid chromatography (GLC). Temperature was varied from 303.15K to 423.15K to allow transport calculations for different seasons. Four PDMS polymers with average molecular weight ranging from 760 to 13 000 were used as solvents. Linear plots of log Vg against 1 T were obtained in all cases permitting predictions and interpolations to temperatures not studied here and also dependable enthalpies and entropies of solute transfer from the mobile phase to the stationary phase can be calculated. The specific retention volumes reported in this work are in agreement with literature for similar systems. Efforts were taken to ensure the best possible accuracy and trace the possible sources of error. We devised a gas liquid chromatographic system which secured a simple retention mechanism and showed reproducible solute retention over a long period of time.
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- Authors: Muzenda, Edison , Ntuli, Freeman
- Date: 2011
- Subjects: Volatile organic compounds , Gas liquid chromatography
- Type: Article
- Identifier: uj:6240 , http://hdl.handle.net/10210/8181
- Description: This study investigated the influence of temperature on the specific retention volumes ( o g V ) of 13 volatile organic compounds (VOCs) in silicon oil as the liquid stationary phase using gas liquid chromatography (GLC). Temperature was varied from 303.15K to 423.15K to allow transport calculations for different seasons. Four PDMS polymers with average molecular weight ranging from 760 to 13 000 were used as solvents. Linear plots of log Vg against 1 T were obtained in all cases permitting predictions and interpolations to temperatures not studied here and also dependable enthalpies and entropies of solute transfer from the mobile phase to the stationary phase can be calculated. The specific retention volumes reported in this work are in agreement with literature for similar systems. Efforts were taken to ensure the best possible accuracy and trace the possible sources of error. We devised a gas liquid chromatographic system which secured a simple retention mechanism and showed reproducible solute retention over a long period of time.
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Glycerol - a viable solvent for absorption of highly polar solutes II : behaviour of molecular interactions
- Scheepers, Jacques J., Muzenda, Edison, Belaid, Mohamed
- Authors: Scheepers, Jacques J. , Muzenda, Edison , Belaid, Mohamed
- Date: 2015
- Subjects: Activity coefficients , Glycerol , Solubility , Volatile organic compounds , Scrubbing solvents
- Type: Article
- Identifier: uj:5054 , http://hdl.handle.net/10210/13593
- Description: This work focused on the potential of glycerol as a scrubbing solvent for stripping of highly polar volatile organic compounds (VOCs) from industrial waste gas streams. Results for glycerol interactions were compared to those of water. Solubility predictions in the form of infinite dilution activity coefficients were made using the Modified UNIFAC Dortmund group contribution model, which was set up on a Microsoft Excel spreadsheet specifically designed for this purpose. Activity coefficients for VOCs in water and glycerol (highly polar solvents) increased with an increase in the length of the VOC solute nonpolar tail. Furthermore, activity coefficients decreased with an increase in the degree of branching of the VOC solute. The results show that low chain length highly polar alcohol, ketone, organic acid and aldehyde solutes are very soluble in glycerol. Diols, dicarbonyl aldehydes, some ketone derivatives and the ethanolamines also show good solubility. Highly polar diesters and ester derivatives are less soluble in glycerol and water. This study has found glycerol to be a better scrubbing solvent than water in treating highly polar VOCs. However it is possible that the standard method of building up the glycerol molecule in the UNIFAC may result in under-predictions of activity coefficients and thus special group interaction parameters for glycerol are required.
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- Authors: Scheepers, Jacques J. , Muzenda, Edison , Belaid, Mohamed
- Date: 2015
- Subjects: Activity coefficients , Glycerol , Solubility , Volatile organic compounds , Scrubbing solvents
- Type: Article
- Identifier: uj:5054 , http://hdl.handle.net/10210/13593
- Description: This work focused on the potential of glycerol as a scrubbing solvent for stripping of highly polar volatile organic compounds (VOCs) from industrial waste gas streams. Results for glycerol interactions were compared to those of water. Solubility predictions in the form of infinite dilution activity coefficients were made using the Modified UNIFAC Dortmund group contribution model, which was set up on a Microsoft Excel spreadsheet specifically designed for this purpose. Activity coefficients for VOCs in water and glycerol (highly polar solvents) increased with an increase in the length of the VOC solute nonpolar tail. Furthermore, activity coefficients decreased with an increase in the degree of branching of the VOC solute. The results show that low chain length highly polar alcohol, ketone, organic acid and aldehyde solutes are very soluble in glycerol. Diols, dicarbonyl aldehydes, some ketone derivatives and the ethanolamines also show good solubility. Highly polar diesters and ester derivatives are less soluble in glycerol and water. This study has found glycerol to be a better scrubbing solvent than water in treating highly polar VOCs. However it is possible that the standard method of building up the glycerol molecule in the UNIFAC may result in under-predictions of activity coefficients and thus special group interaction parameters for glycerol are required.
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Absorption of volatile organic compounds into polydimethylsiloxane : phase equilibrium computation at infinite dilution
- Muzenda, Edison, Mateescu, Corina M.
- Authors: Muzenda, Edison , Mateescu, Corina M.
- Date: 2011
- Subjects: Volatile organic compounds , Polydimethylsiloxane , UNIFAC group contribution methods
- Type: Article
- Identifier: uj:5318 , ISSN 2010-3778 , http://hdl.handle.net/10210/8183
- Description: Group contribution methods such as the UNIFAC are very useful to researchers and engineers involved in synthesis, feasibility studies, design and optimization of separation processes. They can be applied successfully to predict phase equilibrium and excess properties in the development of chemical and separation processes. The main focus of this work was to investigate the possibility of absorbing selected volatile organic compounds (VOCs) into polydimethylsiloxane (PDMS) using three selected UNIFAC group contribution methods. Absorption followed by subsequent stripping is the predominant available abatement technology of VOCs from flue gases prior to their release into the atmosphere. The original, modified and effective UNIFAC models were used in this work. The thirteen selected VOCs that have been considered in this research are: pentane, hexane, heptanes, trimethylamine, toluene, xylene, cyclohexane, butyl acetate, diethyl acetate, chloroform, acetone, ethyl methyl ketone and isobutyl methyl ketone. The computation was done for solute VOC concentration of 8.55x10-8 which is well in the infinite dilution region. The results obtained in this study compare very well with those published in literature obtained through both measurements and predictions. The phase equilibrium obtained in this study show that PDMS is a good absorbent for the removal of VOCs from contaminated air streams through physical absorption.
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- Authors: Muzenda, Edison , Mateescu, Corina M.
- Date: 2011
- Subjects: Volatile organic compounds , Polydimethylsiloxane , UNIFAC group contribution methods
- Type: Article
- Identifier: uj:5318 , ISSN 2010-3778 , http://hdl.handle.net/10210/8183
- Description: Group contribution methods such as the UNIFAC are very useful to researchers and engineers involved in synthesis, feasibility studies, design and optimization of separation processes. They can be applied successfully to predict phase equilibrium and excess properties in the development of chemical and separation processes. The main focus of this work was to investigate the possibility of absorbing selected volatile organic compounds (VOCs) into polydimethylsiloxane (PDMS) using three selected UNIFAC group contribution methods. Absorption followed by subsequent stripping is the predominant available abatement technology of VOCs from flue gases prior to their release into the atmosphere. The original, modified and effective UNIFAC models were used in this work. The thirteen selected VOCs that have been considered in this research are: pentane, hexane, heptanes, trimethylamine, toluene, xylene, cyclohexane, butyl acetate, diethyl acetate, chloroform, acetone, ethyl methyl ketone and isobutyl methyl ketone. The computation was done for solute VOC concentration of 8.55x10-8 which is well in the infinite dilution region. The results obtained in this study compare very well with those published in literature obtained through both measurements and predictions. The phase equilibrium obtained in this study show that PDMS is a good absorbent for the removal of VOCs from contaminated air streams through physical absorption.
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Phase equilibrium of volatile organic compounds in silicon oil using the UNIFAC procedure : an estimation
- Muzenda, Edison, Simate, Geoffrey S., Belaid, Mohamed, Ntuli, Freeman, Mollagee, Mansoor
- Authors: Muzenda, Edison , Simate, Geoffrey S. , Belaid, Mohamed , Ntuli, Freeman , Mollagee, Mansoor
- Date: 2011
- Subjects: Phase equilibrium , Thermodynamic models , Volatile organic compounds , Polydimethylsiloxane , Silicon oil
- Type: Article
- Identifier: uj:4699 , http://hdl.handle.net/10210/10934
- Description: This paper focuses on the phase equilibrium of volatile organic compounds in silicon oil chemically known as PDMS (polydimethylsiloxane) at infinite dilution. Measurements can be expensive and time consuming, hence the need for thermodynamic models which allow the calculation of the phase equilibrium behavior using a limited number of experimental data. The objective of this study was to predict infinite dilution activity coefficients of selected VOCs (volatile organic compounds) in PDMS using the Original UNIFAC model. The predicted results show that PDMS can be used to abate volatile organic compounds from contaminated air streams. The results obtained in this work are comparable to those obtained by the same authors through measurements such as the static headspace and the dynamic gas liquid chromatographic techniques as well as other literature. Although the UNIFAC group contribution method over estimate the infinite dilution activity coefficients, the results of this work may be applied in preliminary phases of process design, simulation and feasibility studies.
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- Authors: Muzenda, Edison , Simate, Geoffrey S. , Belaid, Mohamed , Ntuli, Freeman , Mollagee, Mansoor
- Date: 2011
- Subjects: Phase equilibrium , Thermodynamic models , Volatile organic compounds , Polydimethylsiloxane , Silicon oil
- Type: Article
- Identifier: uj:4699 , http://hdl.handle.net/10210/10934
- Description: This paper focuses on the phase equilibrium of volatile organic compounds in silicon oil chemically known as PDMS (polydimethylsiloxane) at infinite dilution. Measurements can be expensive and time consuming, hence the need for thermodynamic models which allow the calculation of the phase equilibrium behavior using a limited number of experimental data. The objective of this study was to predict infinite dilution activity coefficients of selected VOCs (volatile organic compounds) in PDMS using the Original UNIFAC model. The predicted results show that PDMS can be used to abate volatile organic compounds from contaminated air streams. The results obtained in this work are comparable to those obtained by the same authors through measurements such as the static headspace and the dynamic gas liquid chromatographic techniques as well as other literature. Although the UNIFAC group contribution method over estimate the infinite dilution activity coefficients, the results of this work may be applied in preliminary phases of process design, simulation and feasibility studies.
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