Modification of polyethersulfone by grafting acrylic-acid based monomers for improved hydrophilicity and pH-responsive properties of membranes
- Authors: Kgatle, Masaku
- Date: 2016
- Subjects: Water - Purification - Membrane filtration , Membrane filters , Nanofiltration , Graft copolymers , Polymeric composites
- Language: English
- Type: Masters (Thesis)
- Identifier: http://hdl.handle.net/10210/124976 , uj:20981
- Description: Abstract: The quality of drinking water is continuously deteriorating due to pollutants that end up in water arising from a variety of industries. These pollutants reduce the value of water thereby posing risks to people’s health and the environment. Thus, there is a need to develop techniques that will be effective in wastewater treatment to obtain potable water. Membrane technology has increasingly become the most reliable, applicable and cost-effective technique for drinking water treatment solution. However, membrane fouling has been identified as the major obstacle to the applicability of this technique. In order to alleviate this issue, many studies have proved that improving the hydrophilicity of a membrane surface is significant. In this study, acrylic acid (AA)-based monomers (acrylic acid (AA), methacrylic acid (MAA) and ethylene glycol dimethacrylate (EGDMA)) were graft-polymerized onto hydrophobic polyethersulfone (PES) using benzoyl peroxide (BPO) as the chemical initiator for the development of membranes with pH-responsive and antifouling properties. The confirmation of successful grafting was done using nuclear magnetic resonance (NMR) and fourier transform infrared (FTIR) spectroscopies. Flat-sheet pristine and grafted PES membranes were prepared by phase inversion via immersion precipitation technique. The morphology of the membranes was studied using scanning electron microscopy (SEM) and atomic force microscopy (AFM). Furthermore, membrane hydrophilicity and performance were investigated using contact angle measurements and dead-end filtration (pure water flux, bovine serum albumin (BSA) rejection and fouling analysis). The SEM analysis showed an increase in the pore size of the PES-g-PAA, PES-g-PMAA and PES-g-PEGDMA membranes in comparison with the pristine PES membrane. The contact angle measurements indicated significant increases in the hydrophilicities with chemical grafting of the AA-based monomers onto PES. The pH-responsive tests proved that the grafted PES membranes all... , M.Sc. (Chemistry)
- Full Text:
- Authors: Kgatle, Masaku
- Date: 2016
- Subjects: Water - Purification - Membrane filtration , Membrane filters , Nanofiltration , Graft copolymers , Polymeric composites
- Language: English
- Type: Masters (Thesis)
- Identifier: http://hdl.handle.net/10210/124976 , uj:20981
- Description: Abstract: The quality of drinking water is continuously deteriorating due to pollutants that end up in water arising from a variety of industries. These pollutants reduce the value of water thereby posing risks to people’s health and the environment. Thus, there is a need to develop techniques that will be effective in wastewater treatment to obtain potable water. Membrane technology has increasingly become the most reliable, applicable and cost-effective technique for drinking water treatment solution. However, membrane fouling has been identified as the major obstacle to the applicability of this technique. In order to alleviate this issue, many studies have proved that improving the hydrophilicity of a membrane surface is significant. In this study, acrylic acid (AA)-based monomers (acrylic acid (AA), methacrylic acid (MAA) and ethylene glycol dimethacrylate (EGDMA)) were graft-polymerized onto hydrophobic polyethersulfone (PES) using benzoyl peroxide (BPO) as the chemical initiator for the development of membranes with pH-responsive and antifouling properties. The confirmation of successful grafting was done using nuclear magnetic resonance (NMR) and fourier transform infrared (FTIR) spectroscopies. Flat-sheet pristine and grafted PES membranes were prepared by phase inversion via immersion precipitation technique. The morphology of the membranes was studied using scanning electron microscopy (SEM) and atomic force microscopy (AFM). Furthermore, membrane hydrophilicity and performance were investigated using contact angle measurements and dead-end filtration (pure water flux, bovine serum albumin (BSA) rejection and fouling analysis). The SEM analysis showed an increase in the pore size of the PES-g-PAA, PES-g-PMAA and PES-g-PEGDMA membranes in comparison with the pristine PES membrane. The contact angle measurements indicated significant increases in the hydrophilicities with chemical grafting of the AA-based monomers onto PES. The pH-responsive tests proved that the grafted PES membranes all... , M.Sc. (Chemistry)
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Preparation of doped nanotitanium dioxide (TIO2) immobilized on polyethersulphone (PES) nanofiberes for photocatalytic degradation of water pollutants
- Authors: Chabalala, Mandla Brian
- Date: 2016
- Subjects: Water - Purification - Photocatalysis , Photocatalysis , Nanofiltration , Titanium dioxide
- Language: English
- Type: Masters (Thesis)
- Identifier: http://hdl.handle.net/10210/84406 , uj:19216
- Description: Abstract: As the world’s population continue to grow annually, the demand of drinking water also increases. Countries that are facing water scarcity are currently facing high demand rates of clean water. One of the major contributors to water scarcity is water pollution; this is often caused by the release of wastewater by various sectors which include factories, industries and laboratories, among others. Such wastewater contains toxic materials which end up in drinking water sources and these materials are suspected of being endocrine-disruptive-chemicals (EDCs). The increase in concentrations of contaminants (particularly dyes) in water show that conventional wastewater treatments methods are not efficient enough, hence advanced technologies such as Advanced Oxidation Processes (AOPs) should be implemented to treat persistent contaminants in water. AOPs are characterized by the production of highly reactive hydroxyl (HO•) and superoxide (O2-•) anion radicals, which are suitable for a rapid, continuous and indiscriminative reaction with organic compounds inducing almost complete degradation. Such AOPs include the Fenton’s process which uses peroxide-iron (II) (H2O2/Fe2+) as the Fenton reagent and Photocatalysis which makes use of semiconductors such as titanium dioxide (TiO2). AOPs are classified as clean technology for the treatment of wastewater and can degrade micro pollutants with reaction rate of up to 109 Lmol-1s-1 yielding CO2, H2O and inorganic ions as the final products Pristine and doped TiO2 photocatalysts were prepared using a modified sol-gel method in both acidic and basic medium. The loading of N was varied from 1 to 5 %. Polyethersulphone (PES) nanofibers were electrospun from a PES polymer solution that was prepared by dissolving PES in N,N-Dimethylfomamide (DMF) at room temperature overnight. The polymer solutions of concentration 18 to 29 % PES/DMF (m/m %) were obtained. The resulting solutions were electrospun at the following conditions: 20 - 25 cm tip to collector distance, 12 kV working voltage and 0.5 ml flow rate. The electrospinning of PES/Photocatalyst (PES/PC) nanofiber was performed under the optimized conditions of PES nanofibers. The photocatalysts loading was varied between 1.5, 2 and 2.5 % while PES was , M.Sc. (Chemistry)
- Full Text:
- Authors: Chabalala, Mandla Brian
- Date: 2016
- Subjects: Water - Purification - Photocatalysis , Photocatalysis , Nanofiltration , Titanium dioxide
- Language: English
- Type: Masters (Thesis)
- Identifier: http://hdl.handle.net/10210/84406 , uj:19216
- Description: Abstract: As the world’s population continue to grow annually, the demand of drinking water also increases. Countries that are facing water scarcity are currently facing high demand rates of clean water. One of the major contributors to water scarcity is water pollution; this is often caused by the release of wastewater by various sectors which include factories, industries and laboratories, among others. Such wastewater contains toxic materials which end up in drinking water sources and these materials are suspected of being endocrine-disruptive-chemicals (EDCs). The increase in concentrations of contaminants (particularly dyes) in water show that conventional wastewater treatments methods are not efficient enough, hence advanced technologies such as Advanced Oxidation Processes (AOPs) should be implemented to treat persistent contaminants in water. AOPs are characterized by the production of highly reactive hydroxyl (HO•) and superoxide (O2-•) anion radicals, which are suitable for a rapid, continuous and indiscriminative reaction with organic compounds inducing almost complete degradation. Such AOPs include the Fenton’s process which uses peroxide-iron (II) (H2O2/Fe2+) as the Fenton reagent and Photocatalysis which makes use of semiconductors such as titanium dioxide (TiO2). AOPs are classified as clean technology for the treatment of wastewater and can degrade micro pollutants with reaction rate of up to 109 Lmol-1s-1 yielding CO2, H2O and inorganic ions as the final products Pristine and doped TiO2 photocatalysts were prepared using a modified sol-gel method in both acidic and basic medium. The loading of N was varied from 1 to 5 %. Polyethersulphone (PES) nanofibers were electrospun from a PES polymer solution that was prepared by dissolving PES in N,N-Dimethylfomamide (DMF) at room temperature overnight. The polymer solutions of concentration 18 to 29 % PES/DMF (m/m %) were obtained. The resulting solutions were electrospun at the following conditions: 20 - 25 cm tip to collector distance, 12 kV working voltage and 0.5 ml flow rate. The electrospinning of PES/Photocatalyst (PES/PC) nanofiber was performed under the optimized conditions of PES nanofibers. The photocatalysts loading was varied between 1.5, 2 and 2.5 % while PES was , M.Sc. (Chemistry)
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Incorporation of zwitterion modified graphene oxide onto thin-film composite layer to enhance flix and solute rejection
- Authors: Xabela, Sinethemba Snezz
- Date: 2019
- Subjects: Nanostructured materials , Membrane separation , Graft copolymers , Nanofiltration , Membrane filters
- Language: English
- Type: Masters (Thesis)
- Identifier: http://hdl.handle.net/10210/401694 , uj:33583
- Description: Abstract : In this work, surface Zwitterion functionalization of graphene oxide (GO) was carried out by grafting poly(sulfobetaine methacrylate) (PSBMA) onto the GO surface by means of reverse atom transfer radical polymerization (RATRP) approach to generate GO-PSBMA nanoplates. GO-PSBMA was characterized by Fourier transforms infrared spectra (FT-IR), thermal gravimetric analysis (TGA), X-Ray Diffraction (XRD), Raman spectroscopy and Transmission Electron Microscopy (TEM) techniques. The influence of GO-PSBMA was investigated on different membrane polymers by incorporating different amounts of this additive into cellulose acetate (CA) and polyphenylsulfone (PPSU) casting solutions through phase inversion method, initially for the removal of both organic dyes and salts in water. Furthermore, GO-PSBMA was incorporated into the polyamide (PA) selective layer to develop a novel thin-film composite (TFC) membrane for desalination application. The effect of GO-PSBMA on the morphology and surface property of the CA, PPSU and TFC membranes was examined using Scanning Electron Microscopy (SEM), Atomic Force Microscopy (AFM) and ATR-FTIR. The contact angle (CA), pure water flux (PWF) and antifouling properties of modified membranes were also used to investigate the membranes performance. On cellulose acetate hybrid membranes, it was found that the water flux of the hybrid membrane was greatly enhanced from 100.71 L.m-2.h-1 to 258.39 L.m-2.h-1 when the GO-PSBMA content increased from 0 to 0.5 wt.%. The antifouling tests revealed that the GO-PSBMA embedded membranes had an excellent antifouling performance: a high flux recovery ratio (FRR) (93%) and a low total flux decline ratio (0.01%). Additionally, the hybrid membranes exhibited a distinct advance in the mechanical strength due to the addition of highly rigid GO. Notably, compared with unmodified CA membranes, the hybrid membranes had a higher retention of CR dye (99.01%), MO dye (84%) and MB dye (95%), and a lower rejection of salts at an operational pressure of 900 kPa, rendering the membranes... , M.Sc. (Chemistry)
- Full Text:
- Authors: Xabela, Sinethemba Snezz
- Date: 2019
- Subjects: Nanostructured materials , Membrane separation , Graft copolymers , Nanofiltration , Membrane filters
- Language: English
- Type: Masters (Thesis)
- Identifier: http://hdl.handle.net/10210/401694 , uj:33583
- Description: Abstract : In this work, surface Zwitterion functionalization of graphene oxide (GO) was carried out by grafting poly(sulfobetaine methacrylate) (PSBMA) onto the GO surface by means of reverse atom transfer radical polymerization (RATRP) approach to generate GO-PSBMA nanoplates. GO-PSBMA was characterized by Fourier transforms infrared spectra (FT-IR), thermal gravimetric analysis (TGA), X-Ray Diffraction (XRD), Raman spectroscopy and Transmission Electron Microscopy (TEM) techniques. The influence of GO-PSBMA was investigated on different membrane polymers by incorporating different amounts of this additive into cellulose acetate (CA) and polyphenylsulfone (PPSU) casting solutions through phase inversion method, initially for the removal of both organic dyes and salts in water. Furthermore, GO-PSBMA was incorporated into the polyamide (PA) selective layer to develop a novel thin-film composite (TFC) membrane for desalination application. The effect of GO-PSBMA on the morphology and surface property of the CA, PPSU and TFC membranes was examined using Scanning Electron Microscopy (SEM), Atomic Force Microscopy (AFM) and ATR-FTIR. The contact angle (CA), pure water flux (PWF) and antifouling properties of modified membranes were also used to investigate the membranes performance. On cellulose acetate hybrid membranes, it was found that the water flux of the hybrid membrane was greatly enhanced from 100.71 L.m-2.h-1 to 258.39 L.m-2.h-1 when the GO-PSBMA content increased from 0 to 0.5 wt.%. The antifouling tests revealed that the GO-PSBMA embedded membranes had an excellent antifouling performance: a high flux recovery ratio (FRR) (93%) and a low total flux decline ratio (0.01%). Additionally, the hybrid membranes exhibited a distinct advance in the mechanical strength due to the addition of highly rigid GO. Notably, compared with unmodified CA membranes, the hybrid membranes had a higher retention of CR dye (99.01%), MO dye (84%) and MB dye (95%), and a lower rejection of salts at an operational pressure of 900 kPa, rendering the membranes... , M.Sc. (Chemistry)
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