Henry Mungondori | University of Fort Hare (original) (raw)

Papers by Henry Mungondori

Asian Journal of Chemistry, 2020

Herein, the preparation, characterization and applications of novel carbon doped titanium dioxide... more Herein, the preparation, characterization and applications of novel carbon doped titanium dioxide and tin oxide nanocomposite supported on coal fly ash (C-TiO2-SnO2/CFA) are reported. The nanocomposite nanoparticles were successfully synthesized by a sol-gel method and calcined at 550 ºC. XRD analysis showed that SnO2 nanoparticles were polycrystalline in nature and TiO2 had both anatase and rutile phases. Diffuse reflectance spectra showed that carbon doping reduced the band gap of TiO2 from 3.19 eV to 2.78 eV. The nanoparticles′ photocatalytic activity was evaluated using methyl orange and methylene blue dyes, under both UV light and solar irradiation at different pH, pollutant concentration and photocatalyst loading. High photodegradation rates of methyl orange were achieved under visible light. The optimum loading of composite photocatalyst was 0.4 g with removal efficiencies of 97.75% for methyl orange and 99.25% for methylene blue after 3 h. High removal efficiencies were achi...

Water Science and Technology, 2019

This work investigates the preparation of a magnetically recoverable photocatalytic nanocomposite... more This work investigates the preparation of a magnetically recoverable photocatalytic nanocomposite of maghemite nanoparticles coated with silica and carbon doped titanium dioxide. The novel nanocomposite boasts the advantages of efficient photocatalytic degradation of organic pollutants in water and ease of recovery of the fine particles after water treatment. The photocatalytic nanocomposite was successfully synthesized through a stepwise approach via co-precipitation and sol-gel methods. Characterisation by Fourier transform infrared (FTIR), X-ray diffraction (XRD), transmission electron microscopy (TEM) and energy dispersive spectroscopy (EDS) substantiated the existence of the intended structure of the nanocomposite and the particles were found to be in the size range of 15–22 nm with a quasi-spherical shape. Brunauer–Emmett–Teller (BET) surface area analysis revealed an average surface area of 55.20 m2/g, which is higher than that of commercial TiO2 (Degussa P25, 50.00 m2/g), an...

Water Science and Technology, 2017

The adsorption of a multi-component system of ferrous, chromium, copper, nickel and lead on singl... more The adsorption of a multi-component system of ferrous, chromium, copper, nickel and lead on single, binary and ternary composites was studied. The aim of the study was to investigate whether a ternary composite of clay, peanut husks (PH) and saw-dust (SD) exhibited a higher adsorption capacity than that of a binary system of clay and SD as well as a single component adsorbent of PH alone. The materials were used in their raw state without any chemical modifications. This was done to retain the cost effective aspect of the naturally occurring adsorbents. The adsorption capacities of the ternary composite for the heavy metals Fe2+, Cr3+, Cu2+, Ni2+ and Pb2+ were 41.7 mg/g, 40.0 mg/g, 25.5 mg/g, 41.5 mg/g and 39.0 mg/g, respectively. It was found that the ternary composite exhibited excellent and enhanced adsorption capacity compared with both a binary and single adsorbent for the heavy metals Fe2+, Ni2+ and Cr3+. Characterization of the ternary composites was done using Fourier transf...

Iranian Polymer Journal, 2016

Nitrogen-doped titanium dioxide (N–TiO2) was prepared and supported on a novel copolymer grafted ... more Nitrogen-doped titanium dioxide (N–TiO2) was prepared and supported on a novel copolymer grafted membrane matrix to avoid the problems associated with the removal of spent photocatalyst from treated water. Membranes of poly (methacrylic acid) grafted onto poly (vinylidene difluoride) and blended with poly (acrylonitrile) (PMAA-g-PVDF/PAN) were prepared through a dry–wet phase inversion technique. Methacrylic acid side chains were grafted onto an activated PVDF backbone by the method of reversible addition fragmentation chain transfer polymerization and then the novel photocatalytic asymmetric membranes of N–TiO2–PMAA-g-PVDF/PAN were prepared. The casting solutions were blended with 1–5 % N–TiO2 before immersion into the coagulation bath. PVDF and PAN offer several advantages which include: mechanical strength and toughness, chemical resistance, unaffected by long-term exposure to UV radiation, low weight, and thermal stability. N–TiO2 was prepared through sol-gel synthesis. The photocatalytic membranes were evaluated by degradation process of herbicide bentazon in water. Photodegradation studies revealed that the optimum photocatalyst loading was 3 % N–TiO2 and the optimum pH was 7 for the degradation of bentazon in water. UV–Vis, TOC and LC–MS analyses confirmed the successful photodegradation of bentazon. A bentazon removal efficiency of 90.1 % was achieved at pH 7. N–TiO2–PMAA-g-PVDF/PAN membranes were successfully prepared and characterized. These photocatalytic membranes showed great potential as a technology for the effective removal of pesticides from water. According to literature, N–TiO2–PMAA-g-PVDF/PAN asymmetric photocatalytic membranes have not been prepared before for the purpose of treating agricultural wastewater.

British Journal of Applied Science & Technology, 2015

ABSTRACT Aim: To evaluate the antimicrobial properties of carbon and nitrogen doped titanium diox... more ABSTRACT Aim: To evaluate the antimicrobial properties of carbon and nitrogen doped titanium dioxide (C-TiO 2 and N-TiO 2) immobilized on glass support by examining the inactivation of E. coli ATCC 25922 bacteria in water. Study Design: Sol gel synthesis was used to prepare a series of visible light responsive photo-catalysts of titanium dioxide. The photo-catalysts were characterized via Fourier transform infrared spectroscopy (FT-IR), Scanning X-ray Photoelectron Spectroscopy (SXPS), X-ray Diffraction (XRD), Diffuse reflectance spectroscopy (DRS) and Energy Dispersive X-Ray Spectroscopy (EDS or EDX). Modified titanium dioxide photo-catalysts (TiO 2 -SiO 2 , C-TiO 2 -SiO 2 , and N-TiO 2 -SiO 2) immobilized on glass supports were evaluated for their antimicrobial properties on the inactivation Original Research Article Mungondori et al.; BJAST, 5(5): 447-460, 2015; Article no.BJAST.2015.043 448 of E. coli ATCC 25922 in water. Campus, between July 2013 and November 2013. Methodology: A 0.5 McFarland standard solution containing approximately 1.5×10 8 organisms was prepared by adding Escherichia coli ATCC 25922 to a saline solution (0.85% NaCl). A battery of experiments was carried out to evaluate the antimicrobial properties of glass-immobilized and powder photo-catalysts. Every 30 minutes, swabs were taken from each reactor vessel and placed on the freshly prepared nutrient agar plates. Plates were incubated at 37°C for 24 hours. Results: The number of active E. coli cells after treatment with TiO 2 was determined by colony counting after 24 hours of incubation. When E. coli ATCC 25922 was treated with powder TiO 2 (i), there was a small decrease in the number of colonies within the first 30 minutes, but after exposure for 60 minutes about 98% of the bacterial colonies had been destroyed. Conclusion: Immobilized titanium dioxide photo-catalyst was shown to be less effective in the deactivation of E. coli bacteria. The three nano-composite photo-catalysts; TiO 2 -SiO 2 , C-TiO 2 -SiO 2 , and N-TiO 2 -SiO 2 showed little cytotoxicity (the degree to which an agent possesses a specific destructive action on certain cells) towards the growth of E. coli ATCC 25922 while powder titanium dioxide proved to be very effective towards the inactivation of E. coli ATCC 25922 bacteria.

Materials Science Forum, 2012

The sol gel synthesis method was used to prepare carbon and nitrogen doped titanium dioxide (TiO2... more The sol gel synthesis method was used to prepare carbon and nitrogen doped titanium dioxide (TiO2) photo-catalyst using titanium tetrachloride (TiCl4) as the precursor. Doping was carried out to modify the absorption band edge of titanium dioxide. To avert the problem associated with use of powder TiO2, the photo-catalyst was immobilized on glass support using tetraethyl orthosilicate (TEOS), which served as a binder and precursor for silicon dioxide (SiO2). The prepared photo-catalytic materials were characterized by FT-IR, XRD, TEM, BET and DRS. The photo-catalytic efficiency of titanium dioxide immobilized on glass support was evaluated using the degradation of methyl orange (MeO) and phenol red (PRed) under ultraviolet and visible light irradiation. Doping with carbon and nitrogen, and incorporation of silicon dioxide into the titanium dioxide matrix allowed utilization of visible light by the prepared TiO2-SiO2nanocomposites. Photo-degradation tests were carried out for doped a...

Water Science and Technology, 2017

The aim of this study was to prepare activated carbon from tobacco stalks using microwave heating... more The aim of this study was to prepare activated carbon from tobacco stalks using microwave heating. The prepared activated carbon was applied as an adsorbent in methylene blue (MB) removal from water. The optimum conditions for activated carbon preparation were a radiation power of 280 W for a period of 6 minutes after the impregnation of the precursor material with 30% ZnCl2 for 24 hours. The activated carbon yield and iodine number were 49.43% and 1,264.51 mg/g respectively. The activated carbon also had a point of zero charge of 5.81 with an adsorption capacity of 123.45 mg/g for MB. The optimum conditions for MB adsorption were a pH of 6.5 with an adsorbent dosage of 0.2 g/50 mL at 25 °C. The MB adsorption kinetics followed the pseudo second order kinetic model with the intra-particle diffusion model suggesting a two-step adsorption mechanism. The adsorption data also fitted well within the Langmuir adsorption isotherm model. Tobacco stalks can successfully be turned into an econ...

Materials Research Express, 2019

Asian Journal of Chemistry, 2022

This study reports a novel magnetic nanoadsorbent prepared from magnetite (Fe3O4) as the magnetic... more This study reports a novel magnetic nanoadsorbent prepared from magnetite (Fe3O4) as the magnetic core, activated carbon from coal fly ash and an ionic liquid (1-methyl-3-ethylimidazolium chloride). The magnetic nanoadsorbent was synthesized via co-precipitation and characterized by FTIR, XRD, TEM, EDS and BET surface area analysis. Batch adsorption studies on cadmium (Cd2+) and lead (Pb2+) solutions such as effect of pH, contact time and adsorbent dosage were carried out. The data was analyzed using the Langmuir and Freundlich models. The results revealed that the optimal adsorption conditions for both metal ions on synthesized nanoadsorbent were pH 6, 200 min, adsorbent dosage of 1.5 g/L, initial ion concentration of 10 ppm and a temperature of 25 ºC. The data obtained in the adsorption of Cd2+ and Pb2+ best fitted the Freundlich isotherm, with R2 values of 0.998 and 0.995, respectively. Thermodynamic and kinetic studies suggested that adsorption of both metal ions on the IL-AC-Fe...

Water Science and Technology, 2016

The aim of this study was to evaluate the photo-catalytic properties of nitrogen-doped titanium d... more The aim of this study was to evaluate the photo-catalytic properties of nitrogen-doped titanium dioxide nano-particles supported on polymer membranes in the photo-reduction of Fe(3+) and Pb(2+) from synthetic wastewater. The morphology of the prepared N-TiO2 nanoparticles was evaluated using transmission electron microscopy. Successful grafting of methacrylic acid side chains onto poly(vinylidene difluoride) (PVDF) backbone was confirmed by Fourier-transform infrared spectroscopy. The photo-catalytic asymmetric membranes were prepared through the dry-wet phase inversion technique. The asymmetric morphology was evaluated using scanning electron microscopy. The highest Fe(3+) photo-reduction efficiency (76.2%) was achieved in 6 hours using 1% N-TiO2-PMAA-g-PVDF/PAN (PMAA: poly(methacrylic acid); PAN: poly(acrylonitrile)) asymmetric membrane under solar irradiation. Increasing the photo-catalyst loading to 3% was found to negatively impact the photo-reduction of Fe(3+). Very high photo-reduction efficiencies were observed in the photo-reduction of Pb(2+) using 1% N-TiO2-PAN, 1% N-TiO2-PMAA-g-PVDF/PAN and 1% N-TiO2-PVDF membranes (90.5%, 88.9% and 86.9%, respectively) under similar conditions. Increasing the photo-catalyst loading to 3% N-TiO2 was observed to slightly increase the photo-reduction efficiency in the removal of Pb(2+) unlike in the case of Fe(3+). The best support material for the N-TiO2 photo-catalyst was PMAA-g-PVDF/PAN.

A thesis submitted to the University of Fort Hare in fulfilment of the requirements for the award... more A thesis submitted to the University of Fort Hare in fulfilment of the requirements for the award of the degree of Master of Science in Chemistry

COPYRIGHT © The Author(s) Published under a Creative Commons Attribution 4.0 International Licenc... more COPYRIGHT © The Author(s) Published under a Creative Commons Attribution 4.0 International Licence (CC BY 4.0) Surface water pollution has increased, owing to industrial development and population growth. Consequently, it is important to find alternative drinking water treatment strategies, which cater for changes in the quality of raw water. This study compared the efficiency of different coagulants in treating raw water that feeds a drinking water treatment plant (WTP). Using jar testing equipment and a number of physicochemical parameters, an investigation was conducted to establish optimum conditions for aluminium chloride (A), ferric chloride (B), and chitosan (C), and their performance compared with aluminium sulphate (D), which is the coagulant used at the WTP. The turbidity removal efficiencies for the single coagulants were in the order: B (95.7%) > A (94.7%) > C (94.4%), at optimum coagulant doses of 60, 50, and 0.6 mg/L, respectively. The coagulants achieved high re...

Catalysts

The existence of dye effluent in environmental water bodies is becoming a growing concern to envi... more The existence of dye effluent in environmental water bodies is becoming a growing concern to environmentalists and civilians due to negative health effects. In this study, a novel poly(acrylonitrile)-membrane-supported carbon-doped titanium dioxide–coal fly ash nanocomposite (C-TiO2-CFA/PAN) was prepared and evaluated in the removal of textiles dyes (methyl orange and golden yellow) in water. The C-TiO2-CFA nanocomposite was prepared via sol-gel synthesis and immobilized on PAN membrane prepared via phase inversion technique. The photocatalyst was characterized by FTIR, XRD, BET surface area analysis, SEM, EDX, and DRS. FTIR analysis confirmed the existence of the expected functional groups, and XRD revealed that the C-TiO2 was predominantly in the anatase phase, which exhibited the highest photocatalytic activity. The optimum C-TiO2-CFA photocatalyst load on the PAN membrane was 2% w/w, and it achieved degradation efficiencies of 99.86% and 99.20% for MO and GY dyes, respectively, ...

Journal of Nanotechnology

Reusable photocatalytic polyacrylonitrile membrane-supported cadmium sulphide/titanium dioxide hy... more Reusable photocatalytic polyacrylonitrile membrane-supported cadmium sulphide/titanium dioxide hybrid nanoparticles (CdS/TiO2-PAN) were prepared using a dry-wet phase inversion technique. Scanning electron microscopy (SEM) analysis revealed that the photocatalytic membranes had a porous sublayer, a compact top layer, and that, some of the nanoparticles were not encapsulated by the membranes. The average crystallite sizes of the CdS, TiO2, and CdS/TiO2 hybrid nanoparticles were 3.41 nm, 10.47 nm, and 12.17 nm, respectively. The combination of CdS and TiO2 nanoparticles led to a red shift (band gap; ca. 2.6 eV) of the absorption band and extended the optical absorption spectrum into the visible region relative to TiO2. The photocatalytic activity of CdS/TiO2-PAN membranes was explored in the degradation of methylene blue dye under visible light irradiation, and the results revealed that the best photocatalytic performance was achieved by 0.1 g CdS/TiO2-PAN photocatalytic membrane with...

Titanium Dioxide - Material for a Sustainable Environment, Jun 27, 2018

Titanium dioxide (TiO 2) semiconductor nanoparticles are one kind of important and promising phot... more Titanium dioxide (TiO 2) semiconductor nanoparticles are one kind of important and promising photocatalysts in photocatalysis because of their unique optical and electronic properties. Their properties, which are determined by the preparation method, are very crucial in photocatalysis. In this chapter, an overview was carried out on the different methods that are used or have been used to prepare titanium dioxide nanoparticles. There are various methods that can be used to synthesize TiO 2 and the most commonly used methods include sol-gel process, chemical vapor deposition (CVD) and hydrothermal method among others. This review will focus on selected preparation methods of titanium dioxide photocatalyst.

Aim: To evaluate the antimicrobial properties of carbon and nitrogen doped titanium dioxide (CTiO... more Aim: To evaluate the antimicrobial properties of carbon and nitrogen doped titanium dioxide (CTiO2 and N-TiO2) immobilized on glass support by examining the inactivation of E. coli ATCC 25922 bacteria in water. Study Design: Sol gel synthesis was used to prepare a series of visible light responsive photocatalysts of titanium dioxide. The photo-catalysts were characterized via Fourier transform infrared
spectroscopy (FT-IR), Scanning X-ray Photoelectron spectroscopy (SXPS), X-ray Diffraction (XRD), Diffuse reflectance spectroscopy (DRS) and Energy Dispersive X-Ray Spectroscopy (EDS or EDX). Modified titanium dioxide photo-catalysts (TiO2-SiO2, C-TiO2-SiO2, and N-TiO2-SiO2) immobilized on glass supports were evaluated for their antimicrobial properties on the inactivation of E. coli ATCC 25922 in water.
Place and Duration of Study: Department of Chemistry (Water Research Group) and Department of Biochemistry and Microbiology, University of Fort Hare Alice Campus, between July 2013 and November 2013.
Methodology: A 0.5 McFarland standard solution containing approximately 1.5×108 organisms was prepared by adding Escherichia coli ATCC 25922 to a saline solution (0.85% NaCl). A battery of experiments was carried out to evaluate the antimicrobial properties of glass-immobilized and powder photo-catalysts. Every 30 minutes, swabs were taken from each reactor vessel and placed on the freshly prepared nutrient agar plates. Plates were incubated at 37°C for 24 hours.
Results: The number of active E. coli cells after treatment with TiO2 was determined by colony counting after 24 hours of incubation. When E. coli ATCC 25922 was treated with powder TiO2 (i), there was a small decrease in the number of colonies within the first 30 minutes, but after exposure for 60 minutes about 98% of the bacterial colonies had been destroyed.
Conclusion: Immobilized titanium dioxide photo-catalyst was shown to be less effective in the deactivation of E. coli bacteria. The three nano-composite photo-catalysts; TiO2-SiO2, C-TiO2-SiO2, and N-TiO2-SiO2 showed little cytotoxicity (the degree to which an agent possesses a specific destructive action on certain cells) towards the growth of E. coli ATCC 25922 while powder titanium dioxide proved to be very effective towards the inactivation of E. coli ATCC 25922 bacteria.

The sol gel synthesis method was used to prepare carbon and nitrogen doped titanium dioxide (TiO2... more The sol gel synthesis method was used to prepare carbon and nitrogen doped titanium dioxide (TiO2) photo-catalyst using titanium tetrachloride (TiCl4) as the precursor. Doping was
carried out to modify the absorption band edge of titanium dioxide. To avert the problem associated with use of powder TiO2, the photo-catalyst was immobilized on glass support using tetraethyl orthosilicate (TEOS), which served as a binder and precursor for silicon dioxide (SiO2). The prepared photo-catalytic materials were characterized by FT-IR, XRD, TEM, BET and DRS. The photo-catalytic efficiency of titanium dioxide immobilized on glass support was evaluated using the degradation of methyl orange (MeO) and phenol red (PRed) under ultraviolet and visible light irradiation. Doping with carbon and nitrogen, and incorporation of silicon dioxide into the titanium dioxide matrix allowed utilization of visible light by the prepared TiO2-SiO2 nano-composites. Photo-degradation tests were carried out for doped and undoped photo-catalyst. An increased rate of photo-oxidation of methyl orange and phenol red was observed under visible light irradiation as compared to UV light irradiation.

Asian Journal of Chemistry, 2020

Herein, the preparation, characterization and applications of novel carbon doped titanium dioxide... more Herein, the preparation, characterization and applications of novel carbon doped titanium dioxide and tin oxide nanocomposite supported on coal fly ash (C-TiO2-SnO2/CFA) are reported. The nanocomposite nanoparticles were successfully synthesized by a sol-gel method and calcined at 550 ºC. XRD analysis showed that SnO2 nanoparticles were polycrystalline in nature and TiO2 had both anatase and rutile phases. Diffuse reflectance spectra showed that carbon doping reduced the band gap of TiO2 from 3.19 eV to 2.78 eV. The nanoparticles′ photocatalytic activity was evaluated using methyl orange and methylene blue dyes, under both UV light and solar irradiation at different pH, pollutant concentration and photocatalyst loading. High photodegradation rates of methyl orange were achieved under visible light. The optimum loading of composite photocatalyst was 0.4 g with removal efficiencies of 97.75% for methyl orange and 99.25% for methylene blue after 3 h. High removal efficiencies were achi...

Water Science and Technology, 2019

This work investigates the preparation of a magnetically recoverable photocatalytic nanocomposite... more This work investigates the preparation of a magnetically recoverable photocatalytic nanocomposite of maghemite nanoparticles coated with silica and carbon doped titanium dioxide. The novel nanocomposite boasts the advantages of efficient photocatalytic degradation of organic pollutants in water and ease of recovery of the fine particles after water treatment. The photocatalytic nanocomposite was successfully synthesized through a stepwise approach via co-precipitation and sol-gel methods. Characterisation by Fourier transform infrared (FTIR), X-ray diffraction (XRD), transmission electron microscopy (TEM) and energy dispersive spectroscopy (EDS) substantiated the existence of the intended structure of the nanocomposite and the particles were found to be in the size range of 15–22 nm with a quasi-spherical shape. Brunauer–Emmett–Teller (BET) surface area analysis revealed an average surface area of 55.20 m2/g, which is higher than that of commercial TiO2 (Degussa P25, 50.00 m2/g), an...

Water Science and Technology, 2017

The adsorption of a multi-component system of ferrous, chromium, copper, nickel and lead on singl... more The adsorption of a multi-component system of ferrous, chromium, copper, nickel and lead on single, binary and ternary composites was studied. The aim of the study was to investigate whether a ternary composite of clay, peanut husks (PH) and saw-dust (SD) exhibited a higher adsorption capacity than that of a binary system of clay and SD as well as a single component adsorbent of PH alone. The materials were used in their raw state without any chemical modifications. This was done to retain the cost effective aspect of the naturally occurring adsorbents. The adsorption capacities of the ternary composite for the heavy metals Fe2+, Cr3+, Cu2+, Ni2+ and Pb2+ were 41.7 mg/g, 40.0 mg/g, 25.5 mg/g, 41.5 mg/g and 39.0 mg/g, respectively. It was found that the ternary composite exhibited excellent and enhanced adsorption capacity compared with both a binary and single adsorbent for the heavy metals Fe2+, Ni2+ and Cr3+. Characterization of the ternary composites was done using Fourier transf...

Iranian Polymer Journal, 2016

Nitrogen-doped titanium dioxide (N–TiO2) was prepared and supported on a novel copolymer grafted ... more Nitrogen-doped titanium dioxide (N–TiO2) was prepared and supported on a novel copolymer grafted membrane matrix to avoid the problems associated with the removal of spent photocatalyst from treated water. Membranes of poly (methacrylic acid) grafted onto poly (vinylidene difluoride) and blended with poly (acrylonitrile) (PMAA-g-PVDF/PAN) were prepared through a dry–wet phase inversion technique. Methacrylic acid side chains were grafted onto an activated PVDF backbone by the method of reversible addition fragmentation chain transfer polymerization and then the novel photocatalytic asymmetric membranes of N–TiO2–PMAA-g-PVDF/PAN were prepared. The casting solutions were blended with 1–5 % N–TiO2 before immersion into the coagulation bath. PVDF and PAN offer several advantages which include: mechanical strength and toughness, chemical resistance, unaffected by long-term exposure to UV radiation, low weight, and thermal stability. N–TiO2 was prepared through sol-gel synthesis. The photocatalytic membranes were evaluated by degradation process of herbicide bentazon in water. Photodegradation studies revealed that the optimum photocatalyst loading was 3 % N–TiO2 and the optimum pH was 7 for the degradation of bentazon in water. UV–Vis, TOC and LC–MS analyses confirmed the successful photodegradation of bentazon. A bentazon removal efficiency of 90.1 % was achieved at pH 7. N–TiO2–PMAA-g-PVDF/PAN membranes were successfully prepared and characterized. These photocatalytic membranes showed great potential as a technology for the effective removal of pesticides from water. According to literature, N–TiO2–PMAA-g-PVDF/PAN asymmetric photocatalytic membranes have not been prepared before for the purpose of treating agricultural wastewater.

British Journal of Applied Science & Technology, 2015

ABSTRACT Aim: To evaluate the antimicrobial properties of carbon and nitrogen doped titanium diox... more ABSTRACT Aim: To evaluate the antimicrobial properties of carbon and nitrogen doped titanium dioxide (C-TiO 2 and N-TiO 2) immobilized on glass support by examining the inactivation of E. coli ATCC 25922 bacteria in water. Study Design: Sol gel synthesis was used to prepare a series of visible light responsive photo-catalysts of titanium dioxide. The photo-catalysts were characterized via Fourier transform infrared spectroscopy (FT-IR), Scanning X-ray Photoelectron Spectroscopy (SXPS), X-ray Diffraction (XRD), Diffuse reflectance spectroscopy (DRS) and Energy Dispersive X-Ray Spectroscopy (EDS or EDX). Modified titanium dioxide photo-catalysts (TiO 2 -SiO 2 , C-TiO 2 -SiO 2 , and N-TiO 2 -SiO 2) immobilized on glass supports were evaluated for their antimicrobial properties on the inactivation Original Research Article Mungondori et al.; BJAST, 5(5): 447-460, 2015; Article no.BJAST.2015.043 448 of E. coli ATCC 25922 in water. Campus, between July 2013 and November 2013. Methodology: A 0.5 McFarland standard solution containing approximately 1.5×10 8 organisms was prepared by adding Escherichia coli ATCC 25922 to a saline solution (0.85% NaCl). A battery of experiments was carried out to evaluate the antimicrobial properties of glass-immobilized and powder photo-catalysts. Every 30 minutes, swabs were taken from each reactor vessel and placed on the freshly prepared nutrient agar plates. Plates were incubated at 37°C for 24 hours. Results: The number of active E. coli cells after treatment with TiO 2 was determined by colony counting after 24 hours of incubation. When E. coli ATCC 25922 was treated with powder TiO 2 (i), there was a small decrease in the number of colonies within the first 30 minutes, but after exposure for 60 minutes about 98% of the bacterial colonies had been destroyed. Conclusion: Immobilized titanium dioxide photo-catalyst was shown to be less effective in the deactivation of E. coli bacteria. The three nano-composite photo-catalysts; TiO 2 -SiO 2 , C-TiO 2 -SiO 2 , and N-TiO 2 -SiO 2 showed little cytotoxicity (the degree to which an agent possesses a specific destructive action on certain cells) towards the growth of E. coli ATCC 25922 while powder titanium dioxide proved to be very effective towards the inactivation of E. coli ATCC 25922 bacteria.

Materials Science Forum, 2012

The sol gel synthesis method was used to prepare carbon and nitrogen doped titanium dioxide (TiO2... more The sol gel synthesis method was used to prepare carbon and nitrogen doped titanium dioxide (TiO2) photo-catalyst using titanium tetrachloride (TiCl4) as the precursor. Doping was carried out to modify the absorption band edge of titanium dioxide. To avert the problem associated with use of powder TiO2, the photo-catalyst was immobilized on glass support using tetraethyl orthosilicate (TEOS), which served as a binder and precursor for silicon dioxide (SiO2). The prepared photo-catalytic materials were characterized by FT-IR, XRD, TEM, BET and DRS. The photo-catalytic efficiency of titanium dioxide immobilized on glass support was evaluated using the degradation of methyl orange (MeO) and phenol red (PRed) under ultraviolet and visible light irradiation. Doping with carbon and nitrogen, and incorporation of silicon dioxide into the titanium dioxide matrix allowed utilization of visible light by the prepared TiO2-SiO2nanocomposites. Photo-degradation tests were carried out for doped a...

Water Science and Technology, 2017

The aim of this study was to prepare activated carbon from tobacco stalks using microwave heating... more The aim of this study was to prepare activated carbon from tobacco stalks using microwave heating. The prepared activated carbon was applied as an adsorbent in methylene blue (MB) removal from water. The optimum conditions for activated carbon preparation were a radiation power of 280 W for a period of 6 minutes after the impregnation of the precursor material with 30% ZnCl2 for 24 hours. The activated carbon yield and iodine number were 49.43% and 1,264.51 mg/g respectively. The activated carbon also had a point of zero charge of 5.81 with an adsorption capacity of 123.45 mg/g for MB. The optimum conditions for MB adsorption were a pH of 6.5 with an adsorbent dosage of 0.2 g/50 mL at 25 °C. The MB adsorption kinetics followed the pseudo second order kinetic model with the intra-particle diffusion model suggesting a two-step adsorption mechanism. The adsorption data also fitted well within the Langmuir adsorption isotherm model. Tobacco stalks can successfully be turned into an econ...

Materials Research Express, 2019

Asian Journal of Chemistry, 2022

This study reports a novel magnetic nanoadsorbent prepared from magnetite (Fe3O4) as the magnetic... more This study reports a novel magnetic nanoadsorbent prepared from magnetite (Fe3O4) as the magnetic core, activated carbon from coal fly ash and an ionic liquid (1-methyl-3-ethylimidazolium chloride). The magnetic nanoadsorbent was synthesized via co-precipitation and characterized by FTIR, XRD, TEM, EDS and BET surface area analysis. Batch adsorption studies on cadmium (Cd2+) and lead (Pb2+) solutions such as effect of pH, contact time and adsorbent dosage were carried out. The data was analyzed using the Langmuir and Freundlich models. The results revealed that the optimal adsorption conditions for both metal ions on synthesized nanoadsorbent were pH 6, 200 min, adsorbent dosage of 1.5 g/L, initial ion concentration of 10 ppm and a temperature of 25 ºC. The data obtained in the adsorption of Cd2+ and Pb2+ best fitted the Freundlich isotherm, with R2 values of 0.998 and 0.995, respectively. Thermodynamic and kinetic studies suggested that adsorption of both metal ions on the IL-AC-Fe...

Water Science and Technology, 2016

The aim of this study was to evaluate the photo-catalytic properties of nitrogen-doped titanium d... more The aim of this study was to evaluate the photo-catalytic properties of nitrogen-doped titanium dioxide nano-particles supported on polymer membranes in the photo-reduction of Fe(3+) and Pb(2+) from synthetic wastewater. The morphology of the prepared N-TiO2 nanoparticles was evaluated using transmission electron microscopy. Successful grafting of methacrylic acid side chains onto poly(vinylidene difluoride) (PVDF) backbone was confirmed by Fourier-transform infrared spectroscopy. The photo-catalytic asymmetric membranes were prepared through the dry-wet phase inversion technique. The asymmetric morphology was evaluated using scanning electron microscopy. The highest Fe(3+) photo-reduction efficiency (76.2%) was achieved in 6 hours using 1% N-TiO2-PMAA-g-PVDF/PAN (PMAA: poly(methacrylic acid); PAN: poly(acrylonitrile)) asymmetric membrane under solar irradiation. Increasing the photo-catalyst loading to 3% was found to negatively impact the photo-reduction of Fe(3+). Very high photo-reduction efficiencies were observed in the photo-reduction of Pb(2+) using 1% N-TiO2-PAN, 1% N-TiO2-PMAA-g-PVDF/PAN and 1% N-TiO2-PVDF membranes (90.5%, 88.9% and 86.9%, respectively) under similar conditions. Increasing the photo-catalyst loading to 3% N-TiO2 was observed to slightly increase the photo-reduction efficiency in the removal of Pb(2+) unlike in the case of Fe(3+). The best support material for the N-TiO2 photo-catalyst was PMAA-g-PVDF/PAN.

A thesis submitted to the University of Fort Hare in fulfilment of the requirements for the award... more A thesis submitted to the University of Fort Hare in fulfilment of the requirements for the award of the degree of Master of Science in Chemistry

COPYRIGHT © The Author(s) Published under a Creative Commons Attribution 4.0 International Licenc... more COPYRIGHT © The Author(s) Published under a Creative Commons Attribution 4.0 International Licence (CC BY 4.0) Surface water pollution has increased, owing to industrial development and population growth. Consequently, it is important to find alternative drinking water treatment strategies, which cater for changes in the quality of raw water. This study compared the efficiency of different coagulants in treating raw water that feeds a drinking water treatment plant (WTP). Using jar testing equipment and a number of physicochemical parameters, an investigation was conducted to establish optimum conditions for aluminium chloride (A), ferric chloride (B), and chitosan (C), and their performance compared with aluminium sulphate (D), which is the coagulant used at the WTP. The turbidity removal efficiencies for the single coagulants were in the order: B (95.7%) > A (94.7%) > C (94.4%), at optimum coagulant doses of 60, 50, and 0.6 mg/L, respectively. The coagulants achieved high re...

Catalysts

The existence of dye effluent in environmental water bodies is becoming a growing concern to envi... more The existence of dye effluent in environmental water bodies is becoming a growing concern to environmentalists and civilians due to negative health effects. In this study, a novel poly(acrylonitrile)-membrane-supported carbon-doped titanium dioxide–coal fly ash nanocomposite (C-TiO2-CFA/PAN) was prepared and evaluated in the removal of textiles dyes (methyl orange and golden yellow) in water. The C-TiO2-CFA nanocomposite was prepared via sol-gel synthesis and immobilized on PAN membrane prepared via phase inversion technique. The photocatalyst was characterized by FTIR, XRD, BET surface area analysis, SEM, EDX, and DRS. FTIR analysis confirmed the existence of the expected functional groups, and XRD revealed that the C-TiO2 was predominantly in the anatase phase, which exhibited the highest photocatalytic activity. The optimum C-TiO2-CFA photocatalyst load on the PAN membrane was 2% w/w, and it achieved degradation efficiencies of 99.86% and 99.20% for MO and GY dyes, respectively, ...

Journal of Nanotechnology

Reusable photocatalytic polyacrylonitrile membrane-supported cadmium sulphide/titanium dioxide hy... more Reusable photocatalytic polyacrylonitrile membrane-supported cadmium sulphide/titanium dioxide hybrid nanoparticles (CdS/TiO2-PAN) were prepared using a dry-wet phase inversion technique. Scanning electron microscopy (SEM) analysis revealed that the photocatalytic membranes had a porous sublayer, a compact top layer, and that, some of the nanoparticles were not encapsulated by the membranes. The average crystallite sizes of the CdS, TiO2, and CdS/TiO2 hybrid nanoparticles were 3.41 nm, 10.47 nm, and 12.17 nm, respectively. The combination of CdS and TiO2 nanoparticles led to a red shift (band gap; ca. 2.6 eV) of the absorption band and extended the optical absorption spectrum into the visible region relative to TiO2. The photocatalytic activity of CdS/TiO2-PAN membranes was explored in the degradation of methylene blue dye under visible light irradiation, and the results revealed that the best photocatalytic performance was achieved by 0.1 g CdS/TiO2-PAN photocatalytic membrane with...

Titanium Dioxide - Material for a Sustainable Environment, Jun 27, 2018

Titanium dioxide (TiO 2) semiconductor nanoparticles are one kind of important and promising phot... more Titanium dioxide (TiO 2) semiconductor nanoparticles are one kind of important and promising photocatalysts in photocatalysis because of their unique optical and electronic properties. Their properties, which are determined by the preparation method, are very crucial in photocatalysis. In this chapter, an overview was carried out on the different methods that are used or have been used to prepare titanium dioxide nanoparticles. There are various methods that can be used to synthesize TiO 2 and the most commonly used methods include sol-gel process, chemical vapor deposition (CVD) and hydrothermal method among others. This review will focus on selected preparation methods of titanium dioxide photocatalyst.

Aim: To evaluate the antimicrobial properties of carbon and nitrogen doped titanium dioxide (CTiO... more Aim: To evaluate the antimicrobial properties of carbon and nitrogen doped titanium dioxide (CTiO2 and N-TiO2) immobilized on glass support by examining the inactivation of E. coli ATCC 25922 bacteria in water. Study Design: Sol gel synthesis was used to prepare a series of visible light responsive photocatalysts of titanium dioxide. The photo-catalysts were characterized via Fourier transform infrared
spectroscopy (FT-IR), Scanning X-ray Photoelectron spectroscopy (SXPS), X-ray Diffraction (XRD), Diffuse reflectance spectroscopy (DRS) and Energy Dispersive X-Ray Spectroscopy (EDS or EDX). Modified titanium dioxide photo-catalysts (TiO2-SiO2, C-TiO2-SiO2, and N-TiO2-SiO2) immobilized on glass supports were evaluated for their antimicrobial properties on the inactivation of E. coli ATCC 25922 in water.
Place and Duration of Study: Department of Chemistry (Water Research Group) and Department of Biochemistry and Microbiology, University of Fort Hare Alice Campus, between July 2013 and November 2013.
Methodology: A 0.5 McFarland standard solution containing approximately 1.5×108 organisms was prepared by adding Escherichia coli ATCC 25922 to a saline solution (0.85% NaCl). A battery of experiments was carried out to evaluate the antimicrobial properties of glass-immobilized and powder photo-catalysts. Every 30 minutes, swabs were taken from each reactor vessel and placed on the freshly prepared nutrient agar plates. Plates were incubated at 37°C for 24 hours.
Results: The number of active E. coli cells after treatment with TiO2 was determined by colony counting after 24 hours of incubation. When E. coli ATCC 25922 was treated with powder TiO2 (i), there was a small decrease in the number of colonies within the first 30 minutes, but after exposure for 60 minutes about 98% of the bacterial colonies had been destroyed.
Conclusion: Immobilized titanium dioxide photo-catalyst was shown to be less effective in the deactivation of E. coli bacteria. The three nano-composite photo-catalysts; TiO2-SiO2, C-TiO2-SiO2, and N-TiO2-SiO2 showed little cytotoxicity (the degree to which an agent possesses a specific destructive action on certain cells) towards the growth of E. coli ATCC 25922 while powder titanium dioxide proved to be very effective towards the inactivation of E. coli ATCC 25922 bacteria.

The sol gel synthesis method was used to prepare carbon and nitrogen doped titanium dioxide (TiO2... more The sol gel synthesis method was used to prepare carbon and nitrogen doped titanium dioxide (TiO2) photo-catalyst using titanium tetrachloride (TiCl4) as the precursor. Doping was
carried out to modify the absorption band edge of titanium dioxide. To avert the problem associated with use of powder TiO2, the photo-catalyst was immobilized on glass support using tetraethyl orthosilicate (TEOS), which served as a binder and precursor for silicon dioxide (SiO2). The prepared photo-catalytic materials were characterized by FT-IR, XRD, TEM, BET and DRS. The photo-catalytic efficiency of titanium dioxide immobilized on glass support was evaluated using the degradation of methyl orange (MeO) and phenol red (PRed) under ultraviolet and visible light irradiation. Doping with carbon and nitrogen, and incorporation of silicon dioxide into the titanium dioxide matrix allowed utilization of visible light by the prepared TiO2-SiO2 nano-composites. Photo-degradation tests were carried out for doped and undoped photo-catalyst. An increased rate of photo-oxidation of methyl orange and phenol red was observed under visible light irradiation as compared to UV light irradiation.