Alkenes - ester polymeric solvents thermodynamic interactions - Part 1
- Scheepers, Jacques J., Muzenda, Edison
- Authors: Scheepers, Jacques J. , Muzenda, Edison
- Date: 2012
- Subjects: Activity coefficients , Esters , Alkenes , Thermodynamics , Solubility
- Type: Article
- Identifier: uj:6274 , http://hdl.handle.net/10210/8914
- Description: This work focused on the interactions between ester solvents and volatile organic compounds of alkene in nature. Infinite dilution activity coefficients of alkenes in various fatty acid ester solvents were predicted in order to study and thermodynamically understand the nature and effect of the bond interactions involved. Activity coefficients were computed using Microsoft Excel model specifically designed for this purpose. The ester solvent chain length and saturation influenced the solubility of alkene organics. Saturated and longer ester chains gave better absorption performance. Alkenes were found to be more soluble than their alkane counterparts of similar carbon count.
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- Authors: Scheepers, Jacques J. , Muzenda, Edison
- Date: 2012
- Subjects: Activity coefficients , Esters , Alkenes , Thermodynamics , Solubility
- Type: Article
- Identifier: uj:6274 , http://hdl.handle.net/10210/8914
- Description: This work focused on the interactions between ester solvents and volatile organic compounds of alkene in nature. Infinite dilution activity coefficients of alkenes in various fatty acid ester solvents were predicted in order to study and thermodynamically understand the nature and effect of the bond interactions involved. Activity coefficients were computed using Microsoft Excel model specifically designed for this purpose. The ester solvent chain length and saturation influenced the solubility of alkene organics. Saturated and longer ester chains gave better absorption performance. Alkenes were found to be more soluble than their alkane counterparts of similar carbon count.
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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.
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- 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.
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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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Influence of temperature and molecular structure on organics-biodiesel interactions using group contribution methods
- Scheepers, Jacques J., Muzenda, Edison, Belaid, Mohamed
- Authors: Scheepers, Jacques J. , Muzenda, Edison , Belaid, Mohamed
- Date: 2012
- Subjects: Group contribution method , Phase equilibrium , Solubility , Volatile organic compounds , Absorption , Activity coefficients
- Type: Article
- Identifier: uj:4672 , ISBN 978-93-82242-16-1 , http://hdl.handle.net/10210/10437
- Description: Resulting from the trend of increasingly stringent environmental legislation, the drive to secure environmentally friendly absorption solvents has gained much impetus in recent times. In order to design and operate separation processes units, it is essential that the engineer has accurate and reliable knowledge of the phase equilibrium behaviour of the system in question. Since obtaining experimental data on the system can be time-consuming, the use of thermodynamic models is often useful in obtaining preliminary design and feasibility study information. This work examines the suitability of biodiesel (particularly the constituents methyl palmitate and methyl linolenate) as an absorbent solvent for the recovery of volatile organic compounds (VOCs) from waste process gas streams. In particular, activity coefficients were measured in the dilute region in an attempt to predict the effects of molecular structure and temperature on the solubility of the VOCs in the methyl esters under study. The group contribution methods UNIFAC and Modified UNIFAC Dortmund, set up on Microsoft Excel spreadsheets, were used to predict the required phase equilibrium at infinite dilution. The results obtaine
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- Authors: Scheepers, Jacques J. , Muzenda, Edison , Belaid, Mohamed
- Date: 2012
- Subjects: Group contribution method , Phase equilibrium , Solubility , Volatile organic compounds , Absorption , Activity coefficients
- Type: Article
- Identifier: uj:4672 , ISBN 978-93-82242-16-1 , http://hdl.handle.net/10210/10437
- Description: Resulting from the trend of increasingly stringent environmental legislation, the drive to secure environmentally friendly absorption solvents has gained much impetus in recent times. In order to design and operate separation processes units, it is essential that the engineer has accurate and reliable knowledge of the phase equilibrium behaviour of the system in question. Since obtaining experimental data on the system can be time-consuming, the use of thermodynamic models is often useful in obtaining preliminary design and feasibility study information. This work examines the suitability of biodiesel (particularly the constituents methyl palmitate and methyl linolenate) as an absorbent solvent for the recovery of volatile organic compounds (VOCs) from waste process gas streams. In particular, activity coefficients were measured in the dilute region in an attempt to predict the effects of molecular structure and temperature on the solubility of the VOCs in the methyl esters under study. The group contribution methods UNIFAC and Modified UNIFAC Dortmund, set up on Microsoft Excel spreadsheets, were used to predict the required phase equilibrium at infinite dilution. The results obtaine
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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.
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- 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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Intermolecular dynamics between aromatic compounds and ester polymeric solvents
- Scheepers, Jacques J., Muzenda, Edison, Belaid, Mohamed
- Authors: Scheepers, Jacques J. , Muzenda, Edison , Belaid, Mohamed
- Date: 2013
- Subjects: Activity coefficients , Aromatic compounds , Solubility , Esters
- Type: Article
- Identifier: uj:4836 , http://hdl.handle.net/10210/12484
- Description: This work focused on the interactions that occur between ester solvents and simple aromatic solutes. Solutes were selected from various functional groups in their simplest form, and predictions of activity coefficients at infinite dilution were made using the Modified UNIFAC Dortmund group contribution model. The model computation was set up on a Microsoft Excel spreadsheet specifically designed for this purpose. For polar aromatic solutes, solubility decreased with increase in size of the ester solvent molecule and the opposite was found to be true for non-polar solutes. For all aromatic/ ester solvent interactions there was a decrease in activity coefficients with an increase in the degree of ester unsaturation.
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- Authors: Scheepers, Jacques J. , Muzenda, Edison , Belaid, Mohamed
- Date: 2013
- Subjects: Activity coefficients , Aromatic compounds , Solubility , Esters
- Type: Article
- Identifier: uj:4836 , http://hdl.handle.net/10210/12484
- Description: This work focused on the interactions that occur between ester solvents and simple aromatic solutes. Solutes were selected from various functional groups in their simplest form, and predictions of activity coefficients at infinite dilution were made using the Modified UNIFAC Dortmund group contribution model. The model computation was set up on a Microsoft Excel spreadsheet specifically designed for this purpose. For polar aromatic solutes, solubility decreased with increase in size of the ester solvent molecule and the opposite was found to be true for non-polar solutes. For all aromatic/ ester solvent interactions there was a decrease in activity coefficients with an increase in the degree of ester unsaturation.
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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.
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- 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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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.
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- 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.
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Temperature dependence of limiting activity temperature coefficients in C18 Ester solvents - part 2
- Scheepers, Jacques J., Muzenda, Edison
- Authors: Scheepers, Jacques J. , Muzenda, Edison
- Date: 2013
- Subjects: Activity coefficients , Increasing temperature , Biodiesel esters , Solubility
- Type: Article
- Identifier: uj:4961 , http://hdl.handle.net/10210/13062
- Description: This work continued our focus on the influence of temperature on the activity coefficients of biodiesel ester/ VOC (volatile organic compound) interactions. The VOC families studied in this work were alkenes, alkynes, halogenated alkanes and amines. Solubility predictions in the form of infinite dilution activity coefficients were made using the Modified UNIFAC Dortmund group contribution model, and were computed using a Microsoft Excel spreadsheet specifically designed for this purpose. It was found that, with the exception of cyclopentadiene, alkene activity coefficients decreased slightly with increasing temperature thereby generally deviating from ideality. Solubility of alkyne interactions with unsaturated esters increased with increasing temperature, but decreased with saturated ester interactions for the terminal alkynes. With the exception of trichloromethane halogenated alkane activity coefficients decreased with increasing temperature, thus deviating from ideality. Interactions of esters with amines yielded a decrease in activity coefficients with increasing temperature, hence also deviating from ideality.
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- Authors: Scheepers, Jacques J. , Muzenda, Edison
- Date: 2013
- Subjects: Activity coefficients , Increasing temperature , Biodiesel esters , Solubility
- Type: Article
- Identifier: uj:4961 , http://hdl.handle.net/10210/13062
- Description: This work continued our focus on the influence of temperature on the activity coefficients of biodiesel ester/ VOC (volatile organic compound) interactions. The VOC families studied in this work were alkenes, alkynes, halogenated alkanes and amines. Solubility predictions in the form of infinite dilution activity coefficients were made using the Modified UNIFAC Dortmund group contribution model, and were computed using a Microsoft Excel spreadsheet specifically designed for this purpose. It was found that, with the exception of cyclopentadiene, alkene activity coefficients decreased slightly with increasing temperature thereby generally deviating from ideality. Solubility of alkyne interactions with unsaturated esters increased with increasing temperature, but decreased with saturated ester interactions for the terminal alkynes. With the exception of trichloromethane halogenated alkane activity coefficients decreased with increasing temperature, thus deviating from ideality. Interactions of esters with amines yielded a decrease in activity coefficients with increasing temperature, hence also deviating from ideality.
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Theoretical prediction of solubility, reactivity and degradation pathways of selected azo disperse dyes
- Authors: Wahab, Olaide Olalekan
- Date: 2019
- Subjects: Dyes and dyeing , Azo dyes , Solubility
- Language: English
- Type: Doctoral (Thesis)
- Identifier: http://hdl.handle.net/10210/401657 , uj:33578
- Description: Abstract : , Ph.D. (Chemistry)
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- Authors: Wahab, Olaide Olalekan
- Date: 2019
- Subjects: Dyes and dyeing , Azo dyes , Solubility
- Language: English
- Type: Doctoral (Thesis)
- Identifier: http://hdl.handle.net/10210/401657 , uj:33578
- Description: Abstract : , Ph.D. (Chemistry)
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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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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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