Showing items 1 - 20 of 35

Your selections:

Analysis of the biogas productivity from dry anaerobic digestion of organic fraction of municipal solid waste

- Matheri, Anthony Njuguna, Sethunya, Vuiswa Lucia, Belaid, Mohamed, Muzenda, Edison, Ntuli, Freeman

The effect of leaching time and ammonia concentration on the atmospheric leaching of copper

- Ntuli, Freeman, Muzenda, Edison, Ramatsa, Ishmael, Belaid, Mohamed, Kabuba, John

The removal of Ni, Cu & Fe from a mixed metal system using sodium hypophosphite as a reducing agent

- Ngema, Promise Sethembiso, Ntuli, Freeman, Belaid, Mohamed

Volatile organic compounds- biodiesel thermodynamic interactions: influence of temperature

- Ramdharee, Sashay, Muzenda, Edison, Belaid, Mohamed

An investigation into the effect of temperature on the leaching of copper-matte

- Muzenda, Edison, Ramatsa, I.M., Ntuli, Freeman, Belaid, Mohamed, Tshwabi, P.M.

  • Authors: Muzenda, Edison , Ramatsa, I.M. , Ntuli, Freeman , Belaid, Mohamed , Tshwabi, P.M.
  • Date: 2011
  • Subjects: Coppermatte leaching - Effect of temperature , Leaching - Effect of temperature
  • Type: Article
  • Identifier: uj:4703 , http://hdl.handle.net/10210/10944
  • Description: A study was carried out to determine the influence of the temperature and the reaction involved on the leaching of coppermatte. Copper (Cu) bearing matte from Impala Refinery (Pty) Ltd was used in the investigation. The experiments were conducted in a leaching cell submerged in a water bath, with ammonia concentrations (leaching solution) of 3.0M, temperature of 50°C, 60°C and 70°C, pH of 11 and for a time period of 130 minutes. Leaching tests indicated that Cu recovery increased in the temperature range 50°C - 60°C, however at a temperature of 70°C Cu recovery decreases because of cementation process as nickel displace copper. The shrinking core model was used to determine if the leaching process was diffusion controlled, or chemical controlled, or even mixed controlled. It was found that the leaching process could not be determined using the shrinking core model due to the cementation process of Cu. It was concluded that an increase in temperature results in an increase in the Cu recovery however the temperature should not be too high as cementation process increase with increasing temperature.
  • Full Text:

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:

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:

Performance of sodium mercaptobenzothiazole (NMBT) collector on the flotation of Black Mountain ore

- Ikotun, Adeshina G., Muzenda, Edison, Ntuli, Freeman, Belaid, Mohamed

  • Authors: Ikotun, Adeshina G. , Muzenda, Edison , Ntuli, Freeman , Belaid, Mohamed
  • Date: 2012
  • Subjects: Black Mountain ore , Copper metal , Sodium mercaptobenzothiazole
  • Type: Article
  • Identifier: uj:4689 , http://hdl.handle.net/10210/10478
  • Description: This paper investigated the performance of Sodium Mercaptobenzothiazole (NMBT) as a collector in the flotation of Black Mountain ore. The ore contains metals such as lead, copper and zinc and the associated minerals of economic importance are chalcopyrite, galena and sphalerite respectively, with traces of silver. The study evaluated the effectiveness of the collector and how pH affects the recovery of minerals in particular copper. The performance of the collector was influenced by mineral surface chemistry. The experimental test work was conducted at varying pH levels using Denver flotation cell in order to investigate the collector performance in a basic medium. The experiments were conducted at two different test runs of slightly basic solutions of pH 8.5 and 9.0. The results of both fresh ore and floated ore samples were analysed using XRF. Although Black mountain ore contains small quantities of copper as compared to other ores, a significant amount w recovered (±78% of the available copper in the ore), as an indication of the performance of NMBT.
  • Full Text:

A comparative study of volatile organic compounds abatement

- Muzenda, Edison, Belaid, Mohamed

The effect of leaching time and ammonia concentration on the atmospheric leaching of copper

- Ntuli, Freeman, Muzenda, Edison, Ramatsa, Ishmael, Belaid, Mohamed, Kabuba, John

  • Authors: Ntuli, Freeman , Muzenda, Edison , Ramatsa, Ishmael , Belaid, Mohamed , Kabuba, John
  • Date: 2011
  • Subjects: Copper recovery , Leaching , Ammonia concentrations
  • Type: Article
  • Identifier: uj:5319 , ISSN 2010-4618 , http://hdl.handle.net/10210/8195
  • Description: The effects of ammonia concentration and leaching time were investigated to determine the optimum leaching conditions. The experiments were conducted in a leaching cell submerged in a water bath, with ammonia concentrations of 1.5 M, 2.0 M, 2.5 M and 3.0 M and varying leaching time from 0 to 300 min. Ni-Cu matte containing 23% by mass Cu was used in this experimental study. Increase in the concentration of the lixiviant was found to increase recovery when leaching for 130 minutes, with a recovery of 32.86% Cu using 3 M solution of ammonia. An increase in the leaching time resulted in more copper being leached for all lixiviant concentrations. However, leaching with 2 M ammonia solution gave a higher yield of copper compared to higher concentrations. This anomaly could be a result of cementation; Cu is displaced by Ni as Ni is a more electronegative metal than Cu .It was found that at higher concentrations more nickel was extracted.
  • Full Text:

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:

Alkenes - ester polymeric solvents thermodynamic interactions - part 2

- Scheepers, Jacques J., Muzenda, Edison, Belaid, Mohamed

  • Authors: Scheepers, Jacques J. , Muzenda, Edison , Belaid, Mohamed
  • Date: 2012
  • Subjects: Activity coefficients , Esters , Alkenes , Thermodynamics
  • Type: Article
  • Identifier: uj:5341 , http://hdl.handle.net/10210/9581
  • Description: This paper is a continuation of our work reported previously [1] on the interaction between ester solvents and alkene volatile organic compounds (VOCs). The interactions were presented inform of infinite dilution activity coefficients. A Microsoft Excel spreadsheet for the modified UNIFAC Dortmund group contribution method [2] was designed and used in computing the required phase equilibrium. The size of the solvent molecule (biodiesel) relative to the VOC molecule influenced the thermodynamic interactions. The degree of ester (biodiesel) bond saturation influenced the ease in which cyclic VOCs interacted with the solvent compared to their straight chain counterparts. The location of branches such as methyl branches in relation to the double-bonded carbons had an impact on the predicted infinite dilution activity coefficients.
  • Full Text:

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:

Recovery of aluminium oxide from flint clay through H2SO4 leaching

- Muzenda, Edison, Daniels, Angus L., Belaid, Mohamed, Ntuli, Freeman

Multi-criteria analysis of different technologies for the bioenergy recovery from OFMSW

- Matheri, Anthony Njuguna, Mbohwa, Charles, Belaid, Mohamed, Seodigeng, Tumisang, Ngila, Jane Catherine

Feasibility study for a castor oil extraction plant in South Africa

- Belaid, Mohamed, Muzenda, Edison, Mitilene, Getrude, Mollagee, Mansoor

  • Authors: Belaid, Mohamed , Muzenda, Edison , Mitilene, Getrude , Mollagee, Mansoor
  • Date: 2011
  • Subjects: Castor oil extraction
  • Type: Article
  • Identifier: uj:4706 , http://hdl.handle.net/10210/10950
  • Description: A feasibility study for the design and construction of a pilot plant for the extraction of castor oil in South Africa was conducted. The study emphasized the four critical aspects of project feasibility analysis, namely technical, financial, market and managerial aspects. The technical aspect involved research on existing oil extraction technologies, namely: mechanical pressing and solvent extraction, as well as assessment of the proposed production site for both short and long term viability of the project. The site is on the outskirts of Nkomazi village in the Mpumalanga province, where connections for water and electricity are currently underway, potential raw material supply proves to be reliable since the province is known for its commercial farming. The managerial aspect was evaluated based on the fact that the current producer of castor oil will be fully involved in the project while receiving training and technical assistance from Sasol Technology, the TSC and SEDA. Market and financial aspects were evaluated and the project was considered financially viable with a Net Present Value (NPV) of R2 731 687 and an Internal Rate of Return (IRR) of 18% at an annual interest rate of 10.5%. The payback time is 6years for analysis over the first 10 years with a net income of R1 971 000 in the first year. The project was thus found to be feasible with high chance of success while contributing to socio-economic development. It was recommended for lab tests to be conducted to establish process kinetics that would be used in the initial design of the plant.
  • Full Text:

Modelling the kinetic of biogas production from co-digestion of pig waste and grass clippings

- Matheri, Anthony Njuguna, Belaid, Mohamed, Seodigeng, Tumisang, Ngila, Catherine Jane

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.
  • Full Text:

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.
  • Full Text:

Waste to energy bio-digester selection and design model for the organic fraction of municipal solid waste

- Matheri, Anthony Njuguna, Mbohwa, Charles, Ntuli, Freeman, Belaid, Mohamed, Seodigeng, Tumisang, Ngila, Jane Catherine, Njenga, Cecilia Kinuthia

  • Disclaimer
  • Privacy
  • Copyright
  • Contact