Industrial & Engineering Chemistry Research, Mar 26, 2014
ABSTRACT Two types of polysulfone (PS) membranes (one on a non-woven fabric and the other without... more ABSTRACT Two types of polysulfone (PS) membranes (one on a non-woven fabric and the other without the fabric) with nano-sized carbon-covered alumina supported TiO2 (CCA/TiO2) uniformly dispersed in 18 wt % PS casting solution were prepared. TiO2 nanoparticles were added in order to enhance the visible light photodegradation potential of the PS membranes. The influence of CCA/TiO2 nanoparticles on the PS membranes was investigated using Raman, XRD, SEM, TGA, TGA-FTIR characterization and their mechanical strength was determined with an Instron tensile tester. The Raman and XRD results exposed the probability of interactions between the polymer and the CCA/TiO2 nanoparticles, the SEM suggested that these membranes had a high degree of porosity and this might have resulted in an increase in the permeate flux. The membranes were subsequently tested for capability to photodegrade Rhodamine B under visible light illumination. The PS/CCA/TiO2 (with fabric) membrane photodegraded 82.4% of the dye while the PS/CCA/TiO2 (without a fabric) membrane degraded 78.7% of Rhodamine B after 300 min. The photodegradation followed a pseudo first order reaction rate and the apparent rates were 0.00579 and 0.00515 min–1 for PS/CCA/TiO2 (with fabric) membrane and the PS/CCA/TiO2 (without a fabric), respectively. These results are promising in the quest to produce membranes with the added advantage of photodegrading pollutants under visible light.
ABSTRACT This paper reports on the effects of lignin, polyvinyl pyrrolidone and polyethylene glyc... more ABSTRACT This paper reports on the effects of lignin, polyvinyl pyrrolidone and polyethylene glycol as additives to polysulfone ultrafiltration membranes prepared by nonsolvent induced phase separation. The focus is on the mechanical and thermal properties of the resultant membranes. Differential scanning calorimetry (DSC) and thermogravimetric analysis were used to probe the thermal properties, while an Instron tensile tester was used to characterise the mechanical properties. Morphological studies indicate that the porosity of the bottom sub-layer increased with the use of each additive, suggesting that coagulation in the sub-layer differed from that of the top layer. Membranes fabricated using lignin were thermally stable as the residue at 800 oC increased from 13% to 44%, suggesting interaction of lignin with the polymer. The increase in free fractional volume was confirmed by DSC thermograms as the glass transition temperature decreased considerably after incorporating the additives. Generally, the modulus and tensile strength decreased after the introduction of the additives. These results offer new insight into the use of an emerging, cheap and readily available natural additive (lignin) compared to traditional synthetic additives in membrane formation.
Separation science and technology (Print), Sep 4, 2014
Palladium doped titania nanoparticles supported on carbon-covered alumina (CCA/Pd-TiO2) impregnat... more Palladium doped titania nanoparticles supported on carbon-covered alumina (CCA/Pd-TiO2) impregnated polysulfone (PS) membranes were prepared by the phase inversion technique. The nano-sized CCA/Pd-TiO2 nanoparticles were uniformly dispersed in 18 wt% PS casting solution to synthesize CCA/Pd-TiO2 polysulfone membranes (PS/CCA/Pd-TiO2). The amount of the CCA/Pd-TiO2 was varied between 0.25% and 0.5% to form two types of membranes. These were casted on a non-woven fabric. The nanoparticles were added in order to enhance the photodegradation potential of the PS membranes under visible light. Raman, XRD, SEM, TGA, TGA-FTIR was used to characterize the membranes. The mechanical strength of the membranes was determined with an Instron tensile tester. The SEM results suggested that these membranes had a high degree of porosity and the nanoparticles were distributed on and within the PS membrane. The Raman analysis revealed the presence of the nanoparticles within the membrane matrix while the XRD results exposed the probability of interactions between the polymer and the nanoparticles. The two membranes were then tested for their capability to photodegrade Rhodamine B under visible light illumination. The 0.5% PS/CCA/Pd-TiO2 membrane photodegraded 80.4% of the dye while the 0.25% PS/CCA/Pd-TiO2 membrane degraded 70.8% of Rhodamine B over a 270 min period. The photodegradation followed a pseudo first-order reaction rate and the apparent rates were 0.00597 and 0.00448 min−1 for 0.5% PS/CCA/Pd-TiO2 membrane and 0.25% PS/CCA/Pd-TiO2, respectively.
Over the years, there has been an increase in the number of countries facing water stress and sca... more Over the years, there has been an increase in the number of countries facing water stress and scarcity resulting from persistent high temperatures and prolonged dry conditions. These conditions result in an insufficient supply of clean water for human consumption and agricultural purposes. The situation is further compounded by water pollution by organic, inorganic, and microbial species that render some of the available water unusable. Therefore, there is a need to develop advanced water treatment technologies that can complement the current methods to ensure efficient water and wastewater treatment. Efficient treatment of wastewater is key in augmenting the fresh water supply and such water can also be used for crop irrigation, thereby reducing the demand for fresh water. This chapter presents a concise review of the application of various graphene quantum dot-derived nanostructures in water treatment. Such nanostructures have been explored in the catalytic removal of organic poll...
Journal of Inorganic and Organometallic Polymers and Materials, 2010
The effect of nano-particles of TiO2 on the mechanical and thermal properties of sugarcane bagass... more The effect of nano-particles of TiO2 on the mechanical and thermal properties of sugarcane bagasse (SCB)–ethylene co-vinyl acetate (EVA) composite was investigated. Composite materials were prepared using a melt-mix intercalation method on a rheomex mixer coupled with a single screw extruder. differential scanning calorimeter (DSC), thermogravimetric (TG) analyser and an Instron, were used to probe the thermal and mechanical properties
The demand for manufacturing and application of dyes and pigments in textile industries is increa... more The demand for manufacturing and application of dyes and pigments in textile industries is increasing. Almost a quarter of the dyes used are discharged as wastewater and some of them are difficult to treat due to their complex structures. Herein, the adsorption of Congo red dye from aqueous solutions was conducted using natural, low cost, easy available and environmentally friendly materials such as stems from Chromolaena odorata ( C. odorata or CO), an alien invasive plant species in Southern Africa. The adsorption of Congo red dye was investigated in a series of batch experiments to study the effect of contact time, initial concentration, and initial pH on adsorption efficiency. PES/CO adsorbent-based membranes were fabricated using the phase inversion method. Fourier transform infrared spectroscopy (FTIR) confirmed that PES/CO membranes had hydrophilic functional groups. Addition of C. odorata in PES significantly decreased the surface charge of the prepared membranes by 93%. Dye...
Industrial & Engineering Chemistry Research, Mar 26, 2014
ABSTRACT Two types of polysulfone (PS) membranes (one on a non-woven fabric and the other without... more ABSTRACT Two types of polysulfone (PS) membranes (one on a non-woven fabric and the other without the fabric) with nano-sized carbon-covered alumina supported TiO2 (CCA/TiO2) uniformly dispersed in 18 wt % PS casting solution were prepared. TiO2 nanoparticles were added in order to enhance the visible light photodegradation potential of the PS membranes. The influence of CCA/TiO2 nanoparticles on the PS membranes was investigated using Raman, XRD, SEM, TGA, TGA-FTIR characterization and their mechanical strength was determined with an Instron tensile tester. The Raman and XRD results exposed the probability of interactions between the polymer and the CCA/TiO2 nanoparticles, the SEM suggested that these membranes had a high degree of porosity and this might have resulted in an increase in the permeate flux. The membranes were subsequently tested for capability to photodegrade Rhodamine B under visible light illumination. The PS/CCA/TiO2 (with fabric) membrane photodegraded 82.4% of the dye while the PS/CCA/TiO2 (without a fabric) membrane degraded 78.7% of Rhodamine B after 300 min. The photodegradation followed a pseudo first order reaction rate and the apparent rates were 0.00579 and 0.00515 min–1 for PS/CCA/TiO2 (with fabric) membrane and the PS/CCA/TiO2 (without a fabric), respectively. These results are promising in the quest to produce membranes with the added advantage of photodegrading pollutants under visible light.
ABSTRACT This paper reports on the effects of lignin, polyvinyl pyrrolidone and polyethylene glyc... more ABSTRACT This paper reports on the effects of lignin, polyvinyl pyrrolidone and polyethylene glycol as additives to polysulfone ultrafiltration membranes prepared by nonsolvent induced phase separation. The focus is on the mechanical and thermal properties of the resultant membranes. Differential scanning calorimetry (DSC) and thermogravimetric analysis were used to probe the thermal properties, while an Instron tensile tester was used to characterise the mechanical properties. Morphological studies indicate that the porosity of the bottom sub-layer increased with the use of each additive, suggesting that coagulation in the sub-layer differed from that of the top layer. Membranes fabricated using lignin were thermally stable as the residue at 800 oC increased from 13% to 44%, suggesting interaction of lignin with the polymer. The increase in free fractional volume was confirmed by DSC thermograms as the glass transition temperature decreased considerably after incorporating the additives. Generally, the modulus and tensile strength decreased after the introduction of the additives. These results offer new insight into the use of an emerging, cheap and readily available natural additive (lignin) compared to traditional synthetic additives in membrane formation.
Separation science and technology (Print), Sep 4, 2014
Palladium doped titania nanoparticles supported on carbon-covered alumina (CCA/Pd-TiO2) impregnat... more Palladium doped titania nanoparticles supported on carbon-covered alumina (CCA/Pd-TiO2) impregnated polysulfone (PS) membranes were prepared by the phase inversion technique. The nano-sized CCA/Pd-TiO2 nanoparticles were uniformly dispersed in 18 wt% PS casting solution to synthesize CCA/Pd-TiO2 polysulfone membranes (PS/CCA/Pd-TiO2). The amount of the CCA/Pd-TiO2 was varied between 0.25% and 0.5% to form two types of membranes. These were casted on a non-woven fabric. The nanoparticles were added in order to enhance the photodegradation potential of the PS membranes under visible light. Raman, XRD, SEM, TGA, TGA-FTIR was used to characterize the membranes. The mechanical strength of the membranes was determined with an Instron tensile tester. The SEM results suggested that these membranes had a high degree of porosity and the nanoparticles were distributed on and within the PS membrane. The Raman analysis revealed the presence of the nanoparticles within the membrane matrix while the XRD results exposed the probability of interactions between the polymer and the nanoparticles. The two membranes were then tested for their capability to photodegrade Rhodamine B under visible light illumination. The 0.5% PS/CCA/Pd-TiO2 membrane photodegraded 80.4% of the dye while the 0.25% PS/CCA/Pd-TiO2 membrane degraded 70.8% of Rhodamine B over a 270 min period. The photodegradation followed a pseudo first-order reaction rate and the apparent rates were 0.00597 and 0.00448 min−1 for 0.5% PS/CCA/Pd-TiO2 membrane and 0.25% PS/CCA/Pd-TiO2, respectively.
Over the years, there has been an increase in the number of countries facing water stress and sca... more Over the years, there has been an increase in the number of countries facing water stress and scarcity resulting from persistent high temperatures and prolonged dry conditions. These conditions result in an insufficient supply of clean water for human consumption and agricultural purposes. The situation is further compounded by water pollution by organic, inorganic, and microbial species that render some of the available water unusable. Therefore, there is a need to develop advanced water treatment technologies that can complement the current methods to ensure efficient water and wastewater treatment. Efficient treatment of wastewater is key in augmenting the fresh water supply and such water can also be used for crop irrigation, thereby reducing the demand for fresh water. This chapter presents a concise review of the application of various graphene quantum dot-derived nanostructures in water treatment. Such nanostructures have been explored in the catalytic removal of organic poll...
Journal of Inorganic and Organometallic Polymers and Materials, 2010
The effect of nano-particles of TiO2 on the mechanical and thermal properties of sugarcane bagass... more The effect of nano-particles of TiO2 on the mechanical and thermal properties of sugarcane bagasse (SCB)–ethylene co-vinyl acetate (EVA) composite was investigated. Composite materials were prepared using a melt-mix intercalation method on a rheomex mixer coupled with a single screw extruder. differential scanning calorimeter (DSC), thermogravimetric (TG) analyser and an Instron, were used to probe the thermal and mechanical properties
The demand for manufacturing and application of dyes and pigments in textile industries is increa... more The demand for manufacturing and application of dyes and pigments in textile industries is increasing. Almost a quarter of the dyes used are discharged as wastewater and some of them are difficult to treat due to their complex structures. Herein, the adsorption of Congo red dye from aqueous solutions was conducted using natural, low cost, easy available and environmentally friendly materials such as stems from Chromolaena odorata ( C. odorata or CO), an alien invasive plant species in Southern Africa. The adsorption of Congo red dye was investigated in a series of batch experiments to study the effect of contact time, initial concentration, and initial pH on adsorption efficiency. PES/CO adsorbent-based membranes were fabricated using the phase inversion method. Fourier transform infrared spectroscopy (FTIR) confirmed that PES/CO membranes had hydrophilic functional groups. Addition of C. odorata in PES significantly decreased the surface charge of the prepared membranes by 93%. Dye...
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