Fabrication, simulation and techno-economic evaluation of thin film nanocomposite membrane for acid mine drainage treatment
- Ramokgopa, Selaelo Kholofelo
- Authors: Ramokgopa, Selaelo Kholofelo
- Date: 2020
- Subjects: Water - Purification - Membrane filtration , Acid mine drainage - Purification , Nanocomposites (Materials) , Thin films
- Language: English
- Type: Masters (Thesis)
- Identifier: http://hdl.handle.net/10210/480084 , uj:43447
- Description: Abstract: Thin Film Composite (TFC) membrane technology has been applied in the removal of various pollutants from wastewater. TFC membranes have small pore sizes which enable the rejection of multivalent ions such as those found in Acid Mine Drainage (AMD). Also, nanoparticles with desirable properties have been added to TFC membranes to form Thin Film Nanocomposite (TFN) membranes with potentially enhanced properties. A great opportunity is provided for novel and sustainable development of TFN membranes with Carbon Nanotube (CNTs) for the treatment of AMD. CNT-Infused TFN membranes were synthesized to investigate the feasibility for use in synthetic AMD treatment. Flux and rejection under various operating conditions were measured. The addition of CNTs improved flux by up to 50% and reduced heavy metal concentration in AMD up to 95%. Furthermore, rejection followed the sequence Mg2+>Fe3+>Al3+. Design of Experiments (DOE) was used to determine the effects of process parameters (heavy metal concentration, pressure and MWCNT loading) on process optimisation and semi-empirical modelling techniques were conducted on the experimental data. Response Surface Methodology (RSM) was used to evaluate model outputs and Analysis of variance (ANOVA) was used for model validation. Iron concentration, pressure and CNT loading were found to have the most significance on the process followed by magnesium concentration and aluminium concentration according to RSM results... , M.Tech. (Chemical Engineering)
- Full Text:
- Authors: Ramokgopa, Selaelo Kholofelo
- Date: 2020
- Subjects: Water - Purification - Membrane filtration , Acid mine drainage - Purification , Nanocomposites (Materials) , Thin films
- Language: English
- Type: Masters (Thesis)
- Identifier: http://hdl.handle.net/10210/480084 , uj:43447
- Description: Abstract: Thin Film Composite (TFC) membrane technology has been applied in the removal of various pollutants from wastewater. TFC membranes have small pore sizes which enable the rejection of multivalent ions such as those found in Acid Mine Drainage (AMD). Also, nanoparticles with desirable properties have been added to TFC membranes to form Thin Film Nanocomposite (TFN) membranes with potentially enhanced properties. A great opportunity is provided for novel and sustainable development of TFN membranes with Carbon Nanotube (CNTs) for the treatment of AMD. CNT-Infused TFN membranes were synthesized to investigate the feasibility for use in synthetic AMD treatment. Flux and rejection under various operating conditions were measured. The addition of CNTs improved flux by up to 50% and reduced heavy metal concentration in AMD up to 95%. Furthermore, rejection followed the sequence Mg2+>Fe3+>Al3+. Design of Experiments (DOE) was used to determine the effects of process parameters (heavy metal concentration, pressure and MWCNT loading) on process optimisation and semi-empirical modelling techniques were conducted on the experimental data. Response Surface Methodology (RSM) was used to evaluate model outputs and Analysis of variance (ANOVA) was used for model validation. Iron concentration, pressure and CNT loading were found to have the most significance on the process followed by magnesium concentration and aluminium concentration according to RSM results... , M.Tech. (Chemical Engineering)
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Permeable reactive barriers for acid mine drainage treatment : a review
- Shabalala, Ayanda N., Ekolu, Stephen O., Diop, Souleymane
- Authors: Shabalala, Ayanda N. , Ekolu, Stephen O. , Diop, Souleymane
- Date: 2014
- Subjects: Acid mine drainage - Environmental aspects - South Africa , Acid mine drainage - Purification , Permeable reactive barriers , Water - Purification
- Type: Article
- Identifier: uj:5072 , ISBN 9781614994657 , ISBN 9781614994664 , http://hdl.handle.net/10210/13643
- Description: Contaminated water flowing from abandoned mines is one of the most significant contributors to water pollution. Acid mine drainage (AMD) can have severe impacts on aquatic resources, can stunt terrestrial plant growth and harm wetlands, contaminate groundwater, raise water treatment costs, and damage concrete and metal structures. Permeable reactive barriers (PRBs) are one of the passive treatment technologies widely accepted for sustainable in situ remediation of contaminated groundwater and may be used in the management of localised seepage plumes from mine residues that contaminate shallow groundwater. These barriers provide chemical interactions with AMD as the polluted water flows through it. The ability of PRBs to remediate contaminants is dependent on the type of reactive material used. Some of the reactive media remove contaminants through physical contact while others work by altering the biogeochemical processes in the treatment zone, thus providing conditions conducive for contaminant immobilization or (bio) degradation. A variety of materials has been employed to remove contaminants including heavy metals, chlorinated solvents, aromatic hydrocarbons, and pesticides. This paper gives an overview of the PRB technology, which includes the advantages and limitations of the PRB, the types of reactive materials used, laboratory treatability tests used to evaluate suitable reactive materials and to aid in the designing and the implementation of the PRB and the installations schemes used in PRB field application.
- Full Text:
- Authors: Shabalala, Ayanda N. , Ekolu, Stephen O. , Diop, Souleymane
- Date: 2014
- Subjects: Acid mine drainage - Environmental aspects - South Africa , Acid mine drainage - Purification , Permeable reactive barriers , Water - Purification
- Type: Article
- Identifier: uj:5072 , ISBN 9781614994657 , ISBN 9781614994664 , http://hdl.handle.net/10210/13643
- Description: Contaminated water flowing from abandoned mines is one of the most significant contributors to water pollution. Acid mine drainage (AMD) can have severe impacts on aquatic resources, can stunt terrestrial plant growth and harm wetlands, contaminate groundwater, raise water treatment costs, and damage concrete and metal structures. Permeable reactive barriers (PRBs) are one of the passive treatment technologies widely accepted for sustainable in situ remediation of contaminated groundwater and may be used in the management of localised seepage plumes from mine residues that contaminate shallow groundwater. These barriers provide chemical interactions with AMD as the polluted water flows through it. The ability of PRBs to remediate contaminants is dependent on the type of reactive material used. Some of the reactive media remove contaminants through physical contact while others work by altering the biogeochemical processes in the treatment zone, thus providing conditions conducive for contaminant immobilization or (bio) degradation. A variety of materials has been employed to remove contaminants including heavy metals, chlorinated solvents, aromatic hydrocarbons, and pesticides. This paper gives an overview of the PRB technology, which includes the advantages and limitations of the PRB, the types of reactive materials used, laboratory treatability tests used to evaluate suitable reactive materials and to aid in the designing and the implementation of the PRB and the installations schemes used in PRB field application.
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Removal of sulphates from acid mine drainage using barium and organically modified clay
- Authors: Moreroa, Mabatho
- Date: 2015
- Subjects: Acid mine drainage , Acid mine drainage - Purification , Sulfates - Absorption and adsorption , Water - Purification - Organic compounds removal
- Language: English
- Type: Masters (Thesis)
- Identifier: http://hdl.handle.net/10210/212962 , uj:21060
- Description: Abstract: Attapulgite and Mozambican bentonite (MB) were modified by using barium chloride and ammonium cations such as hexadecyltrimethylammonium bromide (HDTMA) and trimethyldecylammonium bromide (TDTMA) to enhance the removal capacity of sulphates from acid mine drainage (AMD). Through the modification process the surface properties of the clays was rendered organophilic. Batch adsorption experiments of the modified clays were done in a thermostatic shaker at different temperatures, mass loading of adsorbent, and cation exchange capacity (CEC) percentages to investigate the sorption behaviour of sulphates from AMD. Characterization of the modified clay that gave the highest removal of sulphates was done using XRF, XRD, FTIR and SEM to investigate the chemical composition of the clay, removal mechanism and structural change of the clay as a result of sorption of sulphates. Attapulgite showed higher removal of sulphates (70.8%) when modified with BaCl2 than the other two surfactants. This maximum removal was achieved at 25oC and 10% w/v clay to AMD. The reaction fitted the Temkin adsorption isotherm and the second order kinetic model. Adsorption of sulphates on attapulgite was not dependent on temperature as the difference in recovery was not statistically significant when temperature was varied. The value of activation energy (23.7kJ/mol) showed that chemisorption was the dominant mechanism of sulphate removal. MB showed higher removal of sulphates (74.0%) when modified with TDTMA. The reaction was endothermic and fitted the Temkin isotherm model and the second order kinetic model. More sulphates were adsorbed at higher temperatures, suggesting that this was an endothermic reaction, which was supported by the positive value of enthalpy. The activation energy for this reaction (-124.8 kJ/mol) showed that physisorption was the dominant mechanism of sulphate removal. Characterization of both clays showed that the sulphates were removed by adsorption and that the modifiers were only adsorbed on the surface of the clay during the cation exchange process without destroying the crystalline structure of the clay. At high solid loading, more sulphates were adsorbed from the AMD sample by both clays. This implied that at higher solid loadings, there are more sites of adsorption and thus, the higher sulphate removal... , M.Tech. (Chemical Engineering)
- Full Text:
- Authors: Moreroa, Mabatho
- Date: 2015
- Subjects: Acid mine drainage , Acid mine drainage - Purification , Sulfates - Absorption and adsorption , Water - Purification - Organic compounds removal
- Language: English
- Type: Masters (Thesis)
- Identifier: http://hdl.handle.net/10210/212962 , uj:21060
- Description: Abstract: Attapulgite and Mozambican bentonite (MB) were modified by using barium chloride and ammonium cations such as hexadecyltrimethylammonium bromide (HDTMA) and trimethyldecylammonium bromide (TDTMA) to enhance the removal capacity of sulphates from acid mine drainage (AMD). Through the modification process the surface properties of the clays was rendered organophilic. Batch adsorption experiments of the modified clays were done in a thermostatic shaker at different temperatures, mass loading of adsorbent, and cation exchange capacity (CEC) percentages to investigate the sorption behaviour of sulphates from AMD. Characterization of the modified clay that gave the highest removal of sulphates was done using XRF, XRD, FTIR and SEM to investigate the chemical composition of the clay, removal mechanism and structural change of the clay as a result of sorption of sulphates. Attapulgite showed higher removal of sulphates (70.8%) when modified with BaCl2 than the other two surfactants. This maximum removal was achieved at 25oC and 10% w/v clay to AMD. The reaction fitted the Temkin adsorption isotherm and the second order kinetic model. Adsorption of sulphates on attapulgite was not dependent on temperature as the difference in recovery was not statistically significant when temperature was varied. The value of activation energy (23.7kJ/mol) showed that chemisorption was the dominant mechanism of sulphate removal. MB showed higher removal of sulphates (74.0%) when modified with TDTMA. The reaction was endothermic and fitted the Temkin isotherm model and the second order kinetic model. More sulphates were adsorbed at higher temperatures, suggesting that this was an endothermic reaction, which was supported by the positive value of enthalpy. The activation energy for this reaction (-124.8 kJ/mol) showed that physisorption was the dominant mechanism of sulphate removal. Characterization of both clays showed that the sulphates were removed by adsorption and that the modifiers were only adsorbed on the surface of the clay during the cation exchange process without destroying the crystalline structure of the clay. At high solid loading, more sulphates were adsorbed from the AMD sample by both clays. This implied that at higher solid loadings, there are more sites of adsorption and thus, the higher sulphate removal... , M.Tech. (Chemical Engineering)
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Treatment of acid mine drainage using low energy advanced oxidation processes
- Authors: Munyengabe, Alexis
- Date: 2021
- Subjects: Acid mine drainage - Purification , Acid mine drainage - Environmental aspects
- Language: English
- Type: Doctoral (Thesis)
- Identifier: http://hdl.handle.net/10210/477456 , uj:43141
- Description: Abstract: Acid mine drainage (AMD) is acidic water characterized by high concentrations of metals such as iron, manganese, and aluminium as well as sulphate ions, that is formed when pyrite minerals are exposed to oxygenated water and bacteria. This type of water may harm the environment due to lower pH value and is a rising problem in gold and coal mining areas. The mining industry is a sector that still has a big problem of high energy consumption during the AMD treatment due to extensive aeration and stirring, which are required to enable the oxidation of ferrous ions. In past decades, some passive and active AMD treatment methods showed to be costly, time and energy-consuming as well as using separate treatment units with a possibility of generating hazardous by-products. However, this study aimed at treating AMD using low energy advanced oxidation processes (AOPs). The AOP considered as an emerging green oxidant, cost-effective and coagulant/flocculant in a single mixing and dosing unit during the treatment of AMD was sodium ferrate (VI) (Na2FeO4) salt. This was successfully prepared through a wet oxidation process by oxidizing liquid FeCl3 with NaOCl in a strong NaOH solution... , Ph.D. (Chemical Sciences)
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- Authors: Munyengabe, Alexis
- Date: 2021
- Subjects: Acid mine drainage - Purification , Acid mine drainage - Environmental aspects
- Language: English
- Type: Doctoral (Thesis)
- Identifier: http://hdl.handle.net/10210/477456 , uj:43141
- Description: Abstract: Acid mine drainage (AMD) is acidic water characterized by high concentrations of metals such as iron, manganese, and aluminium as well as sulphate ions, that is formed when pyrite minerals are exposed to oxygenated water and bacteria. This type of water may harm the environment due to lower pH value and is a rising problem in gold and coal mining areas. The mining industry is a sector that still has a big problem of high energy consumption during the AMD treatment due to extensive aeration and stirring, which are required to enable the oxidation of ferrous ions. In past decades, some passive and active AMD treatment methods showed to be costly, time and energy-consuming as well as using separate treatment units with a possibility of generating hazardous by-products. However, this study aimed at treating AMD using low energy advanced oxidation processes (AOPs). The AOP considered as an emerging green oxidant, cost-effective and coagulant/flocculant in a single mixing and dosing unit during the treatment of AMD was sodium ferrate (VI) (Na2FeO4) salt. This was successfully prepared through a wet oxidation process by oxidizing liquid FeCl3 with NaOCl in a strong NaOH solution... , Ph.D. (Chemical Sciences)
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