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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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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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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