Anthropogenic activities are principally responsible for the manifestation of toxic and carcinoge... more Anthropogenic activities are principally responsible for the manifestation of toxic and carcinogenic hexavalent chromium (Cr(VI)) triggering water pollution that threaten the environment and human health. The World Health Organisation (WHO) restricts Cr(VI) ions concentration to 0.1 and 0.05 mg/L in inland surface water and drinking water, respectively. The available technologies for Cr(VI) ions removal from water were highlighted with emphasis on adsorption technology. Furthermore, the characteristics of several polypyrrole-based adsorbents were scrutinized including amino containing compounds, biosorbents, graphene/graphene oxide, clay materials and many other additives with reported effective Cr(VI) ions uptake. This efficiency in Cr(VI) ions adsorption is attributed to enhanced redox properties, increased number of functional groups and well as synergistic behaviour of the materials making up the composite. The Langmuir isotherm best described the adsorption processes with maxim...
In the present study, <i>Zea mays</i> tassel which is a zero-value agricultural waste... more In the present study, <i>Zea mays</i> tassel which is a zero-value agricultural waste was used to produce a low-cost activated carbon using phosphoric acid as the activating agent. The prepared <i>Z. mays</i> tassel activated carbon (ZMTAC) was characterized by Fourier transform infrared spectroscopy (FTIR) and X-ray diffraction (XRD). The adsorbent was applied for adsorption of an emerging contaminant, metformin hydrochloride (MH) from pharmaceutical effluent. The effects of solution pH, contact time, adsorbent dosage, and initial MH concentration and their interactions were investigated using a response surface methodology following a central composite experimental design (CCD). The optimum experimental conditions were as follows: pH 9.5, contact time 67.50 min, dosage 0.5750 g, and MH concentration 152.50 mg/L. The isotherm data followed Langmuir isotherm model (<i>R</i><sup>2</sup> = 0.979; sum of square deviation, SSD = 0.321). Th...
Abstract: Maize stalk fibres can be used as fillers in natural rubber composites replacing expens... more Abstract: Maize stalk fibres can be used as fillers in natural rubber composites replacing expensive and non-biodegradable inorganic fillers. Maize stalk fibres were chemically modified with acetic anhydride (acetylation) to enhance their compatibility with the hydrophobic rubber polymer matrix. The fibre was characterised using FTIR showing a spectrum with a well defined peak at 1742 cm-1 (attributed to the carbonyl groups –C=O), indicating that new acetyl groups were introduced to cellulose. The curing and physico–mechanical properties of the composite as a function of filler loading was determined and compared with the values obtained using commercial grade hydrated silica. The natural rubber-maize stalk filled composites showed good processing safety in terms of torques and scorch. Compared with untreated maize-natural rubber composites, the acetylated composites exhibited higher mechanical properties, reduced moisture absorption and higher resistant to hydrothermal aging. Based...
This review focuses on catalytic oxidation of organ ic compounds using hydrogen peroxide. Recent ... more This review focuses on catalytic oxidation of organ ic compounds using hydrogen peroxide. Recent research has focused on the use of environmentally friendly oxidants such as oxygen [1,2] to replace stoichiometric toxic heavy metal oxidants such as d ichromate and permanganates [3,4] in organic reactions. Hydrogen peroxide has in recent years be com an increasingly important oxidant in chemical transformations involving organic reaction s [5]. Hydrogen peroxide is a unique oxidant since it produces water as the only byproduct. In c ertain organic reactions, hydrogen peroxide is a better oxidant than oxygen since some oxygen/organi c mixtures may spontaneously ignite [6]. Another merit of using hydrogen peroxide compared t o other low cost oxidants such as sodium peroborate and many organic peroxy acids is its rel ativ ly high stability [5]. The limitation of using hydrogen peroxide as an oxidant in organic reaction s s the unavoidable presence of water as the solvent of the commercia...
The aim of this study is to investigate the possibility of Saccharomyces cerevisiae as an alterna... more The aim of this study is to investigate the possibility of Saccharomyces cerevisiae as an alternative adsorbent for phenol removal from aqueous solution .The Saccharomyces cerevisiae was characterised by Brunauer Emmett Teller (BET) and Fourier transform (FT-IR). Adsorption properties of Saccharomyces cerevisiae towards phenol were systematically investigated, including pH effect, adsorbent dosage, contact time and initial concentration. The adsorption of phenol decreased with increasing pH. The experimental data were analysed by Langmuir and Freundlich models in order to describe the equilibrium isotherms. Equilibrium data fitted well to the Langmuir model with correlating constant (R 2 ) higher than 0.99. The study showed that Saccharomyces cerevisiae could be used as a new and efficient adsorbent material for the removal of phenol from aqueous solution.
The present investigation describes the use of biochar derived from an agricultural waste: the ma... more The present investigation describes the use of biochar derived from an agricultural waste: the maize cob for the biosorption of Cd(II) ion. The biochar was characterized using scanning electron microscopy, surface area analysis, and Fourier transform infra-red spectroscopy. Batch experiments were performed to investigate the effects of parameters such as pH (2.0–8.0), dosage (0.2–1.2 g), contact time (5–300 min), initial metal concentration (10–100 mg L−1), and temperature (20–50 °C). Kinetic data were properly fitted with the pseudo-second-order model, with the qe (cal) value (17.21 mg g−1) closer to the qe (exp) value (18.82 mg g−1). The adsorption data conforms best to the Langmuir isotherm as revealed by the lower non-linear Chi square (χ2) value of 0.15 and a higher correlation value of 0.98 when compared to the Freundlich with a high χ2 value of 2.65 and lower correlation value of 0.96. The maximum adsorption capacity for the biochar was 33.0 mg g−1. The thermodynamic paramete...
ABSTRACT In this study, disposed coal fly ash samples from Zimbabwe were used in synthesis of zeo... more ABSTRACT In this study, disposed coal fly ash samples from Zimbabwe were used in synthesis of zeolites. The method of direct hydrothermal treatment with sodium hydroxide at different concentrations (2, 2.5, 3.5 and 4.5 moldm -3) at a constant temperature of 100°C and activation time of 24 h was applied. Characterisation of coal fly ash and confirmation of occurrence of the zeolite material was done using XRF, XRD, FTIR, and BET techniques. The zeolite materials formed were a mixture of zeolite Na-X (NaAlSi 1.1 O 4 . 22 25H 2 O), zeolite Na-A (Na 2 Al 2 Si 3.3 O 8.86 7H 2 O), zeolite NaP1 (Na 6 Al 6 Si 10 O 32 H 2 O) and zeolite hydroxysodalite (Na 1.08 Al 2 Si 1.68 O 7.441 .8H 2 O). The variety and yield of zeolites formed depend on the concentration of sodium hydroxide used.
This study compares malt quality parameters of finger millet and sorghum. The quality of malt con... more This study compares malt quality parameters of finger millet and sorghum. The quality of malt consequently affects the quality of opaque beer produced. Certain parameters are analyzed before the malt is accepted for beer brewing. Grain samples of finger millet and sorghum were tested for germination energy before malting. The resultant malts were analyzed for moisture, diastatic power and free amino nitrogen. Finger millet achieved 100% germination while sorghum attained 99% germination in 3 days. After 5 days malting finger millet had higher moisture content (44%) than sorghum (48%). In terms of free amino nitrogen, finger millet had an average of 114.3 mg/L whilst sorghum had an average of 138.6 mg/L. Diastatic power for finger millet malt was lower (13.6 SDU/g) than that of sorghum malt (30.3 SDU/g). Finger millet has demonstrated a great potential to be used in the brewing of commercial opaque beer.
International journal of engineering research and technology, 2013
Concentration levels of trihalomethanes in raw and treated water for the city of Gweru were deter... more Concentration levels of trihalomethanes in raw and treated water for the city of Gweru were determined by solvent extraction followed by gas chromatograph detection. The trihalomethanes found were chloroform, dichlorobromomethane, dibromochloromethane and bromoform. Chloroform was the most abundant trihalomethane with concentration levels ranging from 3.70 µg/L to 45.89µg/L. The concentration levels of trihalomethanes increased with increasing distance from the chlorination point . Total trihalomethane concentration in raw water ranged from nondetectable levels to 18.13µg/L and in treated water ranged from 6.83µg/L to 145.50 µg/L. A slight increase in concentration levels of trihalomethanes was shown in warmer months with the highest concentration level of 145.80 µg/L being recorded in September. Generally, the concentration levels obtained were lower than the maximum permissible limits of 460µg/L set by World Health Organisation (WHO).
Leather shavings wastes from the chrome tanning process were used as filler in natural rubber sol... more Leather shavings wastes from the chrome tanning process were used as filler in natural rubber soles. The main purpose of leather shavings was for reinforcement of silicon dioxide. The shavings were ground to a powder and used as filler in rubber compounding. Particle size, zeta potential before and after adding zinc oxide was determined. The soles produced were then characterized by standards tests such as rheological properties, tensile strength, and elongation at break, abrasion resistance, shore hardness, acid resistance and short term aging. The results showed that the formulation containing 8% (w/w) leather shavings could be satisfactorily used to make certain types of soles that are light weight, comfortable and flexible.
Abstract In the present study, Zea mays tassel which is a zero-value agricultural waste was used ... more Abstract In the present study, Zea mays tassel which is a zero-value agricultural waste was used to produce a low-cost activated carbon using phosphoric acid as the activating agent. The prepared Z. mays tassel activated carbon (ZMTAC) was characterized by Fourier transform infrared spectroscopy (FTIR) and X-ray diffraction (XRD). The adsorbent was applied for adsorption of an emerging contaminant, metformin hydrochloride (MH) from pharmaceutical effluent. The effects of solution pH, contact time, adsorbent dosage, and initial MH concentration and their interactions were investigated using a response surface methodology following a central composite experimental design (CCD). The optimum experimental conditions were as follows: pH 9.5, contact time 67.50 min, dosage 0.5750 g, and MH concentration 152.50 mg/L. The isotherm data followed Langmuir isotherm model (R2 = 0.979; sum of square deviation, SSD = 0.321). The saturation adsorption capacity of ZMTAC was 44.84 mg/g at 20 °C. MH adsorption process followed pseudo-second-order kinetics (higher R2 and smaller SSD values). The thermodynamic properties obtained showed that the adsorption process was feasible, endothermic and spontaneous. Consequently, the study demonstrated that Z. mays tassel is a potential precursor for preparation of adsorbents for the removal of the MH from pharmaceutical effluent.
This study evaluates the effectiveness of magnetic biochar (Fe2O3-EC) derived from water hyacinth... more This study evaluates the effectiveness of magnetic biochar (Fe2O3-EC) derived from water hyacinth in the removal of Cu+2 and Zn+2 from aqueous solution. Fe2O3-EC was prepared by chemical coprecipitation of a mixture of FeCl2 and FeCl3 on water hyacinth biomass followed by pyrolysis. The adsorbent was characterized by Fourier transform infrared spectroscopy (FTIR) and scanning electron microscopy (SEM) coupled with energy dispersive spectroscopy (EDX). Batch adsorption studies on the effects of temperature, biosorbent dosage, contact time, and initial metal ion concentration were carried out. Fe2O3-EC exhibited optimum contact time, biosorbent dosage, and pH values of 65 min, 1.2 g, and 6, respectively. Fe2O3-EC exhibited strong magnetic separation ability and high sorption capability. Metal ion adsorption onto the biochar conformed to the Langmuir isotherm. Kinetic studies revealed that the adsorption process followed pseudo-second-order model. The calculated thermodynamic parameter...
Anthropogenic activities are principally responsible for the manifestation of toxic and carcinoge... more Anthropogenic activities are principally responsible for the manifestation of toxic and carcinogenic hexavalent chromium (Cr(VI)) triggering water pollution that threaten the environment and human health. The World Health Organisation (WHO) restricts Cr(VI) ions concentration to 0.1 and 0.05 mg/L in inland surface water and drinking water, respectively. The available technologies for Cr(VI) ions removal from water were highlighted with emphasis on adsorption technology. Furthermore, the characteristics of several polypyrrole-based adsorbents were scrutinized including amino containing compounds, biosorbents, graphene/graphene oxide, clay materials and many other additives with reported effective Cr(VI) ions uptake. This efficiency in Cr(VI) ions adsorption is attributed to enhanced redox properties, increased number of functional groups and well as synergistic behaviour of the materials making up the composite. The Langmuir isotherm best described the adsorption processes with maxim...
In the present study, <i>Zea mays</i> tassel which is a zero-value agricultural waste... more In the present study, <i>Zea mays</i> tassel which is a zero-value agricultural waste was used to produce a low-cost activated carbon using phosphoric acid as the activating agent. The prepared <i>Z. mays</i> tassel activated carbon (ZMTAC) was characterized by Fourier transform infrared spectroscopy (FTIR) and X-ray diffraction (XRD). The adsorbent was applied for adsorption of an emerging contaminant, metformin hydrochloride (MH) from pharmaceutical effluent. The effects of solution pH, contact time, adsorbent dosage, and initial MH concentration and their interactions were investigated using a response surface methodology following a central composite experimental design (CCD). The optimum experimental conditions were as follows: pH 9.5, contact time 67.50 min, dosage 0.5750 g, and MH concentration 152.50 mg/L. The isotherm data followed Langmuir isotherm model (<i>R</i><sup>2</sup> = 0.979; sum of square deviation, SSD = 0.321). Th...
Abstract: Maize stalk fibres can be used as fillers in natural rubber composites replacing expens... more Abstract: Maize stalk fibres can be used as fillers in natural rubber composites replacing expensive and non-biodegradable inorganic fillers. Maize stalk fibres were chemically modified with acetic anhydride (acetylation) to enhance their compatibility with the hydrophobic rubber polymer matrix. The fibre was characterised using FTIR showing a spectrum with a well defined peak at 1742 cm-1 (attributed to the carbonyl groups –C=O), indicating that new acetyl groups were introduced to cellulose. The curing and physico–mechanical properties of the composite as a function of filler loading was determined and compared with the values obtained using commercial grade hydrated silica. The natural rubber-maize stalk filled composites showed good processing safety in terms of torques and scorch. Compared with untreated maize-natural rubber composites, the acetylated composites exhibited higher mechanical properties, reduced moisture absorption and higher resistant to hydrothermal aging. Based...
This review focuses on catalytic oxidation of organ ic compounds using hydrogen peroxide. Recent ... more This review focuses on catalytic oxidation of organ ic compounds using hydrogen peroxide. Recent research has focused on the use of environmentally friendly oxidants such as oxygen [1,2] to replace stoichiometric toxic heavy metal oxidants such as d ichromate and permanganates [3,4] in organic reactions. Hydrogen peroxide has in recent years be com an increasingly important oxidant in chemical transformations involving organic reaction s [5]. Hydrogen peroxide is a unique oxidant since it produces water as the only byproduct. In c ertain organic reactions, hydrogen peroxide is a better oxidant than oxygen since some oxygen/organi c mixtures may spontaneously ignite [6]. Another merit of using hydrogen peroxide compared t o other low cost oxidants such as sodium peroborate and many organic peroxy acids is its rel ativ ly high stability [5]. The limitation of using hydrogen peroxide as an oxidant in organic reaction s s the unavoidable presence of water as the solvent of the commercia...
The aim of this study is to investigate the possibility of Saccharomyces cerevisiae as an alterna... more The aim of this study is to investigate the possibility of Saccharomyces cerevisiae as an alternative adsorbent for phenol removal from aqueous solution .The Saccharomyces cerevisiae was characterised by Brunauer Emmett Teller (BET) and Fourier transform (FT-IR). Adsorption properties of Saccharomyces cerevisiae towards phenol were systematically investigated, including pH effect, adsorbent dosage, contact time and initial concentration. The adsorption of phenol decreased with increasing pH. The experimental data were analysed by Langmuir and Freundlich models in order to describe the equilibrium isotherms. Equilibrium data fitted well to the Langmuir model with correlating constant (R 2 ) higher than 0.99. The study showed that Saccharomyces cerevisiae could be used as a new and efficient adsorbent material for the removal of phenol from aqueous solution.
The present investigation describes the use of biochar derived from an agricultural waste: the ma... more The present investigation describes the use of biochar derived from an agricultural waste: the maize cob for the biosorption of Cd(II) ion. The biochar was characterized using scanning electron microscopy, surface area analysis, and Fourier transform infra-red spectroscopy. Batch experiments were performed to investigate the effects of parameters such as pH (2.0–8.0), dosage (0.2–1.2 g), contact time (5–300 min), initial metal concentration (10–100 mg L−1), and temperature (20–50 °C). Kinetic data were properly fitted with the pseudo-second-order model, with the qe (cal) value (17.21 mg g−1) closer to the qe (exp) value (18.82 mg g−1). The adsorption data conforms best to the Langmuir isotherm as revealed by the lower non-linear Chi square (χ2) value of 0.15 and a higher correlation value of 0.98 when compared to the Freundlich with a high χ2 value of 2.65 and lower correlation value of 0.96. The maximum adsorption capacity for the biochar was 33.0 mg g−1. The thermodynamic paramete...
ABSTRACT In this study, disposed coal fly ash samples from Zimbabwe were used in synthesis of zeo... more ABSTRACT In this study, disposed coal fly ash samples from Zimbabwe were used in synthesis of zeolites. The method of direct hydrothermal treatment with sodium hydroxide at different concentrations (2, 2.5, 3.5 and 4.5 moldm -3) at a constant temperature of 100°C and activation time of 24 h was applied. Characterisation of coal fly ash and confirmation of occurrence of the zeolite material was done using XRF, XRD, FTIR, and BET techniques. The zeolite materials formed were a mixture of zeolite Na-X (NaAlSi 1.1 O 4 . 22 25H 2 O), zeolite Na-A (Na 2 Al 2 Si 3.3 O 8.86 7H 2 O), zeolite NaP1 (Na 6 Al 6 Si 10 O 32 H 2 O) and zeolite hydroxysodalite (Na 1.08 Al 2 Si 1.68 O 7.441 .8H 2 O). The variety and yield of zeolites formed depend on the concentration of sodium hydroxide used.
This study compares malt quality parameters of finger millet and sorghum. The quality of malt con... more This study compares malt quality parameters of finger millet and sorghum. The quality of malt consequently affects the quality of opaque beer produced. Certain parameters are analyzed before the malt is accepted for beer brewing. Grain samples of finger millet and sorghum were tested for germination energy before malting. The resultant malts were analyzed for moisture, diastatic power and free amino nitrogen. Finger millet achieved 100% germination while sorghum attained 99% germination in 3 days. After 5 days malting finger millet had higher moisture content (44%) than sorghum (48%). In terms of free amino nitrogen, finger millet had an average of 114.3 mg/L whilst sorghum had an average of 138.6 mg/L. Diastatic power for finger millet malt was lower (13.6 SDU/g) than that of sorghum malt (30.3 SDU/g). Finger millet has demonstrated a great potential to be used in the brewing of commercial opaque beer.
International journal of engineering research and technology, 2013
Concentration levels of trihalomethanes in raw and treated water for the city of Gweru were deter... more Concentration levels of trihalomethanes in raw and treated water for the city of Gweru were determined by solvent extraction followed by gas chromatograph detection. The trihalomethanes found were chloroform, dichlorobromomethane, dibromochloromethane and bromoform. Chloroform was the most abundant trihalomethane with concentration levels ranging from 3.70 µg/L to 45.89µg/L. The concentration levels of trihalomethanes increased with increasing distance from the chlorination point . Total trihalomethane concentration in raw water ranged from nondetectable levels to 18.13µg/L and in treated water ranged from 6.83µg/L to 145.50 µg/L. A slight increase in concentration levels of trihalomethanes was shown in warmer months with the highest concentration level of 145.80 µg/L being recorded in September. Generally, the concentration levels obtained were lower than the maximum permissible limits of 460µg/L set by World Health Organisation (WHO).
Leather shavings wastes from the chrome tanning process were used as filler in natural rubber sol... more Leather shavings wastes from the chrome tanning process were used as filler in natural rubber soles. The main purpose of leather shavings was for reinforcement of silicon dioxide. The shavings were ground to a powder and used as filler in rubber compounding. Particle size, zeta potential before and after adding zinc oxide was determined. The soles produced were then characterized by standards tests such as rheological properties, tensile strength, and elongation at break, abrasion resistance, shore hardness, acid resistance and short term aging. The results showed that the formulation containing 8% (w/w) leather shavings could be satisfactorily used to make certain types of soles that are light weight, comfortable and flexible.
Abstract In the present study, Zea mays tassel which is a zero-value agricultural waste was used ... more Abstract In the present study, Zea mays tassel which is a zero-value agricultural waste was used to produce a low-cost activated carbon using phosphoric acid as the activating agent. The prepared Z. mays tassel activated carbon (ZMTAC) was characterized by Fourier transform infrared spectroscopy (FTIR) and X-ray diffraction (XRD). The adsorbent was applied for adsorption of an emerging contaminant, metformin hydrochloride (MH) from pharmaceutical effluent. The effects of solution pH, contact time, adsorbent dosage, and initial MH concentration and their interactions were investigated using a response surface methodology following a central composite experimental design (CCD). The optimum experimental conditions were as follows: pH 9.5, contact time 67.50 min, dosage 0.5750 g, and MH concentration 152.50 mg/L. The isotherm data followed Langmuir isotherm model (R2 = 0.979; sum of square deviation, SSD = 0.321). The saturation adsorption capacity of ZMTAC was 44.84 mg/g at 20 °C. MH adsorption process followed pseudo-second-order kinetics (higher R2 and smaller SSD values). The thermodynamic properties obtained showed that the adsorption process was feasible, endothermic and spontaneous. Consequently, the study demonstrated that Z. mays tassel is a potential precursor for preparation of adsorbents for the removal of the MH from pharmaceutical effluent.
This study evaluates the effectiveness of magnetic biochar (Fe2O3-EC) derived from water hyacinth... more This study evaluates the effectiveness of magnetic biochar (Fe2O3-EC) derived from water hyacinth in the removal of Cu+2 and Zn+2 from aqueous solution. Fe2O3-EC was prepared by chemical coprecipitation of a mixture of FeCl2 and FeCl3 on water hyacinth biomass followed by pyrolysis. The adsorbent was characterized by Fourier transform infrared spectroscopy (FTIR) and scanning electron microscopy (SEM) coupled with energy dispersive spectroscopy (EDX). Batch adsorption studies on the effects of temperature, biosorbent dosage, contact time, and initial metal ion concentration were carried out. Fe2O3-EC exhibited optimum contact time, biosorbent dosage, and pH values of 65 min, 1.2 g, and 6, respectively. Fe2O3-EC exhibited strong magnetic separation ability and high sorption capability. Metal ion adsorption onto the biochar conformed to the Langmuir isotherm. Kinetic studies revealed that the adsorption process followed pseudo-second-order model. The calculated thermodynamic parameter...
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