Polysulfone/β-cyclodextrin polyurethane mixed-matrix composite nanofiltration membrane for water treatment
- Authors: Adams, Feyisayo Victoria
- Date: 2013-07-24
- Subjects: Nanofiltration , Membranes (Technology) , Polymers , Water purification - Organic compounds removal
- Type: Thesis
- Identifier: uj:7675 , http://hdl.handle.net/10210/8542
- Description: D.Phil. (Chemistry) , Please refer to full text to view abstract
- Full Text:
- Authors: Adams, Feyisayo Victoria
- Date: 2013-07-24
- Subjects: Nanofiltration , Membranes (Technology) , Polymers , Water purification - Organic compounds removal
- Type: Thesis
- Identifier: uj:7675 , http://hdl.handle.net/10210/8542
- Description: D.Phil. (Chemistry) , Please refer to full text to view abstract
- Full Text:
Dechlorination of PCB77 using Fe/Pd bimetallic nanoparticles immobilized on microfiltration membranes
- Authors: Ndlwana, Lwazi
- Date: 2014-07-01
- Subjects: Dechlorination , Nanofiltration , Polychlorinated biphenyls - Contamination , Water - Purification - Membrane filtration
- Type: Thesis
- Identifier: uj:11643 , http://hdl.handle.net/10210/11356
- Description: M.Sc. (Nanoscience) , Polychlorinated biphenyls (PCBs) are endocrine disrupting compounds (EDCs) and are harmful to humans and the environment. These PCBs are grouped under chlorinated organic compounds (COCs). The PCBs find their way to the environment through human activity such as industrialization and farming. Such activity produces wastes and runoffs that eventually end up in the water we use for drinking, farming and sanitation. It has then become necessary for researchers to find viable methods to remove these compounds from the environment. This is because current water treatment methods are not effective in the removal of the PCBs from water. The stages in the conventional treatment methods may include sand filtration, advanced oxidative processes and coagulation among others. These methods need to be energetically eco-friendly to drive the PCB dechlorination processes. Researchers have used a variety of metallic nanoparticles including bimetallic nanoparticles for the removal of COCs from water. However, nanoparticles tend to agglomerate when not supported - leading to a decrease in their activity. Hence it has become necessary to stabilize or immobilize these nanoparticles on suitable support materials, such as, polymer solutions or solid substrates. Solid substrates including metal oxides, carbon and membranes, are currently being explored. Poly(vinylidene difluoride) microfiltration membranes are especially suitable for this function given the high porosity, chemical inertness and other outstanding physical properties. In this work, the objective was to modify commercially hydrophilized poly(vinylidine)difluoride (PVDF) membranes with poly(ethylene glycol) (PEG). PEG is a bidentate polymer with two –OH groups found on either side of the molecule. The -OH groups allows PEG binding to the PVDF polymer backbone and hence high ability to capture or chelate the metal ions followed by their reduction. Nano-zerovalent metal nanoparticles were formed from these metal ions and chelated into the PEG grafted PVDF membrane to give the composite PVDF-PEG-Fe0. Post addition of the secondary metal was then followed by the introduction of the precomposite to a Pd solution to give the final catalytic membrane (PVDF-PEG-Fe0/Pd0). The use of PEG in this system allows for an even dispersion of the nanoparticles in the composite. The resulting nanocomposite membrane was used for the dechlorination of a polychlorinated biphenyl (PCB 77). Attenuated total reflection- Fourier transform infra red spectroscopy (ATR-FTIR) showed that PEG was successfully grafted onto the PVDF backbone. Optical contact angle measurements (OCA) were taken to determine the change in hydrophilicity of the membrane upon modification. X-ray diffraction spectroscopy (XRD) proved that the Pd and Fe nanoparticles immobilized on the system were indeed zerovalent. Scanning electron microscopy (SEM) images and contact angle measurements suggested a less porous membrane and slightly decreased hydrophilicity after modification. On the SEM micrographs the nanoparticles were observed to be quite evenly distributed in the membrane. Transmission electron microscopy (TEM) showed that the nanoparticles were in the range 20-30 nm in diameter, confirming the particle size values as determined by SEM. For the preliminary dechlorination studies done under ambient conditions, two dimensional column gas chromatography- time of flight- mass spectrometry (GCxGC-TOF-MS) results showed a complete dechlorination of PCB 77. A comparative study of the bare PVDF and catalytic membranes showed a slight difference in adsorption of the total PCB 77 concentrations. The catalytic membrane maintained its activity towards the dechlorination of PCB 77 after multiple regeneration cycles.
- Full Text:
- Authors: Ndlwana, Lwazi
- Date: 2014-07-01
- Subjects: Dechlorination , Nanofiltration , Polychlorinated biphenyls - Contamination , Water - Purification - Membrane filtration
- Type: Thesis
- Identifier: uj:11643 , http://hdl.handle.net/10210/11356
- Description: M.Sc. (Nanoscience) , Polychlorinated biphenyls (PCBs) are endocrine disrupting compounds (EDCs) and are harmful to humans and the environment. These PCBs are grouped under chlorinated organic compounds (COCs). The PCBs find their way to the environment through human activity such as industrialization and farming. Such activity produces wastes and runoffs that eventually end up in the water we use for drinking, farming and sanitation. It has then become necessary for researchers to find viable methods to remove these compounds from the environment. This is because current water treatment methods are not effective in the removal of the PCBs from water. The stages in the conventional treatment methods may include sand filtration, advanced oxidative processes and coagulation among others. These methods need to be energetically eco-friendly to drive the PCB dechlorination processes. Researchers have used a variety of metallic nanoparticles including bimetallic nanoparticles for the removal of COCs from water. However, nanoparticles tend to agglomerate when not supported - leading to a decrease in their activity. Hence it has become necessary to stabilize or immobilize these nanoparticles on suitable support materials, such as, polymer solutions or solid substrates. Solid substrates including metal oxides, carbon and membranes, are currently being explored. Poly(vinylidene difluoride) microfiltration membranes are especially suitable for this function given the high porosity, chemical inertness and other outstanding physical properties. In this work, the objective was to modify commercially hydrophilized poly(vinylidine)difluoride (PVDF) membranes with poly(ethylene glycol) (PEG). PEG is a bidentate polymer with two –OH groups found on either side of the molecule. The -OH groups allows PEG binding to the PVDF polymer backbone and hence high ability to capture or chelate the metal ions followed by their reduction. Nano-zerovalent metal nanoparticles were formed from these metal ions and chelated into the PEG grafted PVDF membrane to give the composite PVDF-PEG-Fe0. Post addition of the secondary metal was then followed by the introduction of the precomposite to a Pd solution to give the final catalytic membrane (PVDF-PEG-Fe0/Pd0). The use of PEG in this system allows for an even dispersion of the nanoparticles in the composite. The resulting nanocomposite membrane was used for the dechlorination of a polychlorinated biphenyl (PCB 77). Attenuated total reflection- Fourier transform infra red spectroscopy (ATR-FTIR) showed that PEG was successfully grafted onto the PVDF backbone. Optical contact angle measurements (OCA) were taken to determine the change in hydrophilicity of the membrane upon modification. X-ray diffraction spectroscopy (XRD) proved that the Pd and Fe nanoparticles immobilized on the system were indeed zerovalent. Scanning electron microscopy (SEM) images and contact angle measurements suggested a less porous membrane and slightly decreased hydrophilicity after modification. On the SEM micrographs the nanoparticles were observed to be quite evenly distributed in the membrane. Transmission electron microscopy (TEM) showed that the nanoparticles were in the range 20-30 nm in diameter, confirming the particle size values as determined by SEM. For the preliminary dechlorination studies done under ambient conditions, two dimensional column gas chromatography- time of flight- mass spectrometry (GCxGC-TOF-MS) results showed a complete dechlorination of PCB 77. A comparative study of the bare PVDF and catalytic membranes showed a slight difference in adsorption of the total PCB 77 concentrations. The catalytic membrane maintained its activity towards the dechlorination of PCB 77 after multiple regeneration cycles.
- Full Text:
Dechlorination of 3, 3’, 4, 4’ – tetrachlorobiphenyl (PCB77) in water, by nickel/iron nanoparticles immobilized on L-lysine/PAA/PVDF membrane
- Authors: Seteni, Bonani
- Date: 2014-11-03
- Subjects: Dechlorination , Nanofiltration , Polychlorinated biphenyls - Decontamination
- Type: Thesis
- Identifier: uj:12730 , http://hdl.handle.net/10210/12620
- Description: M.Sc. (Chemistry) , Zero-valent nanoscale metal, especially iron nanoparticles have attracted significant attention with regards to remediation of organochlorinated compounds in drinking water. For a more rapid and complete dechlorination, a second and usually electronegative element is often added, resulting in the formationof bimetallic nanoparticles. However, in the absence of surfactants,the bimetallic nanoparticles easily aggregate into large particles (if they are not anchored on solid supports) with wide size distributions, thus losing their reactivity. This work reports an in-situ synthesis method of bimetallic nanoparticles immobilized on L-lysine functionalized microfiltration membranes by chemical reduction of metal ions chelated by amine and hydroxyl functional groups of L-lysine on the composite. The immobilization of the nanoparticles on membranes offers many advantages: reduction of particle loss, prevention of particle agglomeration and application under convective flow. The objective of this research wasto produce catalytic filtration membranes for dechlorination of organic compound, PCB-77. This was achieved first by (i) the modification of commercial PVDF to introduce functional groups that render the membrane more hydrophilic and have the ability to capture metal ions through chelation, and secondly (ii) the controlled introduction of catalytic nanoparticles onto the composite membrane surface, anchored through chelation to the surface functional groups. This approach was selected with aview to produce uniform surface distribution of monodispersed bimetallic nanoparticles that are resistant to leaching during the reduction reactions. The modification of the PVDF membrane was achieved by firstly performing an in situ polymerization of acrylic acid followed by covalently bonded L-lysine to the polymerized acrylic acid chains using 1-ethyl-3-(3-dimethylaminopropyl)-carbodiimide hydrochloride (EDC). The Fe ions were introduced to the composite by L-lysine chelation and subsequently reduced to Fe0 with NaBH4, and finally deposition of Ni2+ which later were also reduced to Ni0 with NaBH4. The Fe/Ni bimetallic NPs system was chosen based on its proven ability for the total dechlorination of chlorinated organic compounds. Systematic characterization of the composite was performed using ATR-FTIR, FESEM, EDS, HRTEM, XRD, AFM and Contact Angle measurements. A relatively uniform distribution of Fe/Ni nanoparticles was found in L-lysine/PAA/PVDF membrane. The diameter of Fe/Ni nanoparticles was predominantly within the range 20-30 nm. Furthermore, the mechanism of the catalytic dechlorination of the model compound, PCB 77, was investigated by careful analysis of the reaction products. It is generally known that zero-valent iron undergoes corrosion to provide hydrogen atoms and electrons for the reductive catalytic hydrodechlorination reaction. The second metal in the bimetallic system on the other hand, acts as...
- Full Text:
- Authors: Seteni, Bonani
- Date: 2014-11-03
- Subjects: Dechlorination , Nanofiltration , Polychlorinated biphenyls - Decontamination
- Type: Thesis
- Identifier: uj:12730 , http://hdl.handle.net/10210/12620
- Description: M.Sc. (Chemistry) , Zero-valent nanoscale metal, especially iron nanoparticles have attracted significant attention with regards to remediation of organochlorinated compounds in drinking water. For a more rapid and complete dechlorination, a second and usually electronegative element is often added, resulting in the formationof bimetallic nanoparticles. However, in the absence of surfactants,the bimetallic nanoparticles easily aggregate into large particles (if they are not anchored on solid supports) with wide size distributions, thus losing their reactivity. This work reports an in-situ synthesis method of bimetallic nanoparticles immobilized on L-lysine functionalized microfiltration membranes by chemical reduction of metal ions chelated by amine and hydroxyl functional groups of L-lysine on the composite. The immobilization of the nanoparticles on membranes offers many advantages: reduction of particle loss, prevention of particle agglomeration and application under convective flow. The objective of this research wasto produce catalytic filtration membranes for dechlorination of organic compound, PCB-77. This was achieved first by (i) the modification of commercial PVDF to introduce functional groups that render the membrane more hydrophilic and have the ability to capture metal ions through chelation, and secondly (ii) the controlled introduction of catalytic nanoparticles onto the composite membrane surface, anchored through chelation to the surface functional groups. This approach was selected with aview to produce uniform surface distribution of monodispersed bimetallic nanoparticles that are resistant to leaching during the reduction reactions. The modification of the PVDF membrane was achieved by firstly performing an in situ polymerization of acrylic acid followed by covalently bonded L-lysine to the polymerized acrylic acid chains using 1-ethyl-3-(3-dimethylaminopropyl)-carbodiimide hydrochloride (EDC). The Fe ions were introduced to the composite by L-lysine chelation and subsequently reduced to Fe0 with NaBH4, and finally deposition of Ni2+ which later were also reduced to Ni0 with NaBH4. The Fe/Ni bimetallic NPs system was chosen based on its proven ability for the total dechlorination of chlorinated organic compounds. Systematic characterization of the composite was performed using ATR-FTIR, FESEM, EDS, HRTEM, XRD, AFM and Contact Angle measurements. A relatively uniform distribution of Fe/Ni nanoparticles was found in L-lysine/PAA/PVDF membrane. The diameter of Fe/Ni nanoparticles was predominantly within the range 20-30 nm. Furthermore, the mechanism of the catalytic dechlorination of the model compound, PCB 77, was investigated by careful analysis of the reaction products. It is generally known that zero-valent iron undergoes corrosion to provide hydrogen atoms and electrons for the reductive catalytic hydrodechlorination reaction. The second metal in the bimetallic system on the other hand, acts as...
- Full Text:
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)
- Full Text:
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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