Efficient Photodegradation of Thiocyanate Ions in Mining Wastewater Using a ZnO-BiOI Heterojunction, 2024
This article is an open access article distributed under the terms and conditions of the Creative... more This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY
In this study, a variety of ZnO-based heterojunctions with disparate wt.% doping of WO3 and BiOI ... more In this study, a variety of ZnO-based heterojunctions with disparate wt.% doping of WO3 and BiOI have been prepared for the photodestruction of methyl orange (MO) dye in aqueous solution. The composites were analysed by scanning electron microscopy, energy-dispersive X-ray spectroscopy, X-ray diffraction, optical studies, and nitrogen adsorption-desorption isotherms. The SEM images revealed non-uniform surfaces of the ZnO–BiOI based composites while mostly nodular morphology was observed for all three samples of ZnO-WO3. As the WO3 loading increased, more clustering was detected. The analysed samples exhibited characteristic peaks representative of the triclinic phase of WO3 and the hexagonal wurtzite structure of ZnO, while the diffractogram observed from the materials displayed distinct peaks corresponding to the crystalline phases of both BiOI and ZnO in their pure forms. Further evidence of the samples' characteristics includes the presence of distinct crystalline patterns without any impurity peaks, a red shift in the absorption spectra of the heterostructure, the detection of only the reference elements, and mostly Type IV isotherm adsorption. This study identified the ZnO-[10%]BiOI and ZnO-[10%]WO3 heterojunctions as the best performing photocatalysts, as MO was completely destroyed in 120 and 90 min, respectively. Thus, confirming 10% wt. as the optimal doping concentration for the best photo-activity in this study. The impact of varying process parameters demonstrates that at an elevated photocatalyst mass of 40 mg, both heterojunctions effectively degraded MO. The photodegradation efficiency of MO was more pronounced in strong acidic conditions (pH 2) when compared to high alkaline conditions (pH 11) for the ZnO-[10%]BiOI heterostructure. However, a decrease in performance was observed for both strong acidic and high alkaline pH values when the ZnO-[10%]WO3 heterostructure was applied. The kinetic analysis of the photodegradation study reveals that all the photodegradation experiments can be represented by the pseudo-first-order kinetic model. The findings from this investigation propose that the ZnO-[10%]BiOI heterojunction photocatalyst holds significant potential for the effective treatment of dye-contaminated wastewater.
The aim of the study was to investigate the application of photocatalytic advanced oxidation (PAO... more The aim of the study was to investigate the application of photocatalytic advanced oxidation (PAO) for the treatment of water contaminated with dark humic material from fynbos biome plants, which cannot be treated by conventional methods. The study used a fynbos species (Aspalathus linearis) to create a model wastewater that was compared with a brew made from black tea (Camellia sinensis). Two photocatalysts (TiO2 and ZnO) and three light sources (natural, halogen light, and UV light) were tested, with and without hydrogen peroxide. The treatment of the two teas by only photolysis was observed to be minimal. The study found that natural sunlight was not effective, but a combination of ZnO and halogen lamp exhibited the best performance, with a 60% degradation in 20 min under solar irradiation. The optimum catalyst concentration was identified as 10 g/L for both photocatalysts. The influence of some process parameters showed that a combination of an optimum dose of 5 mM H2O2 and sola...
There are currently no studies on the synthesis and fabrication of ZnO-BiOI and ZnO-WO3 heterojun... more There are currently no studies on the synthesis and fabrication of ZnO-BiOI and ZnO-WO3 heterojunctions for the photocatalytic destruction of 2-chlorobiphenyl.
Comparative analysis of the shallow and deep aquifers of Nsukka SE, Nigeria was studied as a prel... more Comparative analysis of the shallow and deep aquifers of Nsukka SE, Nigeria was studied as a preliminary approach for the underground water resource development of the region. Method of approach involves the identification of rock formations and delineation of their stratigraphic relationships. Activities involved collection and analysis of water samples from boreholes and hand dug wells. A total of 14 water samples were collected (7 from shallow and deep aquifer each) and analyzed for inorganic and organic components. Ca 2+, Na + , Mn 2+ , Cl - , Pb and Cd were analyzed using Atomic absorption spectroscopy. K + was determined using flame photometer method. Copper Cu 2+ was analyzed using spectrophotometer, pH was analyzed with the aid of pH meter, Fe 2+ was determined calorimetrically using Spekker absorption meter; Tds was determined using glass fiber filter. Turbimetric method was used to assess turbidity. Anions like HCO 3 - were also estimated by titrimetric method. ...
Saline intrusion has been a major source of groundwater contaminant in coastal regions. The situa... more Saline intrusion has been a major source of groundwater contaminant in coastal regions. The situation has adversely affected groundwater quality . Being an essential source of freshwater for the teeming population over the world and indeed Nigeria and its suitability for various uses is largely dependent on physico-chemical quality, this study therefore selected for its quality assessment, the coastal aquifer of Buguma in rivers state Nigeria. Water samples collected from various locations using systematic random sampling were subjected to physico-chemical analysis . sodium (Na 2+ ) (288mg/l) chloride(Cl - )(414.7mg/l) and nitrate (N03-)(64.45 mg/l) ions dominated the major ions of sample results and also exceeded the Nigerian Standard for Drinking Water Quality NSDWQ 2007 and WHO drinking water standard 2006. Among the trace elements, Fe 2+ and As ions were above the drinking water regulatory limits of NSDWQ and WHO. Classification techniques were employed to provide an...
British Journal of Applied Science & Technology, 2016
Industrialization has been the major source of waste generation leading to heavy metal accumulati... more Industrialization has been the major source of waste generation leading to heavy metal accumulation in soils. It has become major environmental challenge especially as it affects soil quality, biota, ecosystem processes and ground water pollution. This study was targeted at determining the contributions of human activities on heavy metal levels of soils in Owerri, eastern Nigeria, by applying Index of geo-accumulation (I-geo) and Contaminant factor (Cf) models on heavy metal levels at major locations. Soil samples were collected during the rainy season with the aid of a hand-dug soil auger (2.50 cm diameter) from three different composite sites: refuse dumps, auto-mechanic villages and a control sample from a virgin land at depths of 0-15 cm, 15-30 cm and 30-45 cm respectively. These were subjected to standard chemical analyses. There were significant variations (P<0.05) in heavy metals concentrations at different depths. There were no significant variations (P>0.05) in pH. pH (5.9-5.2) was acidic at different soil depths, which might Original Research Article Ihejirika et al.; BJAST, 12(1): 1-9, 2016; Article no.BJAST.19357 2 favor ionization of metals; electrical conductivity at the contaminated sites was higher (300.4-248.4 μs/cm) than at the control site (195.8-150.6 μS/cm) which might imply high concentration of ionized dissolved chemicals from waste dumpsites. Copper (Cu) from contaminated areas ranged from 19.1-16.4 mg/kg against control value that was insignificant (P>0.05); Lead (Pb) ranged from 58.228.2 mg/kg against 0.4-0.2 mg/kg; Iron (Fe) ranged from 5.6-2.6 mg/kg against 5.6-2.6 mg/kg; Zinc (Zn) ranged from 140.3-119.4 mg/kg against 3.3-2.5 mg/kg of control. I-geo for all metals fell in the categories of 4-5 and >5. All categories with values within 4-5 were soils that were highly polluted to very highly polluted, while those with values greater than 5 were soils that were very highly polluted. The Cf values of metals were quite >1.5 which implied that the activities at the mechanic villages and waste dumpsites contributed significantly to the heavy metal burden of the soils. Anthropogenic impacts on heavy metal levels on the samples were between 97.6 and 99.9%. Anthropogenic activities should be controlled to prevent heavy metal pollution of soils and sustain quality soil health.
Adsorption of Fe 3+ /Fe 2+ from a polluted shallow well water onto a palm kernel shell activated ... more Adsorption of Fe 3+ /Fe 2+ from a polluted shallow well water onto a palm kernel shell activated carbon (PKSAC) has been studied. Batch experiment was adopted to study the Removal efficiency of Fe 3+ /Fe 2+ on varying contact time, temperature, adsorbent loading and concentrations. Equilibrium isotherm and kinetic were also studied. Removal efficiency progressed with contact time till the peak adsorption time of 100 minutes when the efficiency remained at equilibrium. Also, removal efficiency got to equilibrium at the peak values of 80oC, 4.8g and 12.5mg/l for temperature, adsorbent loading and concentration variations respectively. The adsorption isotherm models fitted the isotherm data got at 25oC, 40oC and 80oC in this order; Langmuir > Temkin>Freunlich. The dimensionless separation factor of 0.012, 0.017 and 0.015 for 25oC, 40oC and 80oC respectively confirmed favorable adsorption of Fe 3+ /Fe 2+ on the PKSAC adsorbent. Langmuir adsorption capacity increased from 203.9mg Fe 3+ /Fe 2+/ g to 389.3 mg Fe 3+ /Fe 2+/ g when the temperature increased from 25oC to 40oC but decreased to 308.1 mg Fe 3+ /Fe 2+/ g at Original Research Article American Chemical Science Journal, 4(3): 298-325, 2014 299 temperature of 80oC. The kinetic models described the kinetic study data got at 25oC, 40oC and 80oC as follows; power-function>second-order>Elovick>intra-diffusion>first-order kinetics. Mass transfer through liquid film diffusion controlled the adsorption of Fe 3+ /Fe 2+ onto PKSAC. Negative values of the Thermodynamic parameters (∆ , ∆ and ∆ ) got at various temperature values showed favorability of adsorption of Fe 3+/ Fe 2+ onto PKSAC. It is therefore concluded that PKSAC removed Fe 3+/ Fe 2+ from aqueous solution.
Efficient Photodegradation of Thiocyanate Ions in Mining Wastewater Using a ZnO-BiOI Heterojunction, 2024
This article is an open access article distributed under the terms and conditions of the Creative... more This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY
In this study, a variety of ZnO-based heterojunctions with disparate wt.% doping of WO3 and BiOI ... more In this study, a variety of ZnO-based heterojunctions with disparate wt.% doping of WO3 and BiOI have been prepared for the photodestruction of methyl orange (MO) dye in aqueous solution. The composites were analysed by scanning electron microscopy, energy-dispersive X-ray spectroscopy, X-ray diffraction, optical studies, and nitrogen adsorption-desorption isotherms. The SEM images revealed non-uniform surfaces of the ZnO–BiOI based composites while mostly nodular morphology was observed for all three samples of ZnO-WO3. As the WO3 loading increased, more clustering was detected. The analysed samples exhibited characteristic peaks representative of the triclinic phase of WO3 and the hexagonal wurtzite structure of ZnO, while the diffractogram observed from the materials displayed distinct peaks corresponding to the crystalline phases of both BiOI and ZnO in their pure forms. Further evidence of the samples&#39; characteristics includes the presence of distinct crystalline patterns without any impurity peaks, a red shift in the absorption spectra of the heterostructure, the detection of only the reference elements, and mostly Type IV isotherm adsorption. This study identified the ZnO-[10%]BiOI and ZnO-[10%]WO3 heterojunctions as the best performing photocatalysts, as MO was completely destroyed in 120 and 90 min, respectively. Thus, confirming 10% wt. as the optimal doping concentration for the best photo-activity in this study. The impact of varying process parameters demonstrates that at an elevated photocatalyst mass of 40 mg, both heterojunctions effectively degraded MO. The photodegradation efficiency of MO was more pronounced in strong acidic conditions (pH 2) when compared to high alkaline conditions (pH 11) for the ZnO-[10%]BiOI heterostructure. However, a decrease in performance was observed for both strong acidic and high alkaline pH values when the ZnO-[10%]WO3 heterostructure was applied. The kinetic analysis of the photodegradation study reveals that all the photodegradation experiments can be represented by the pseudo-first-order kinetic model. The findings from this investigation propose that the ZnO-[10%]BiOI heterojunction photocatalyst holds significant potential for the effective treatment of dye-contaminated wastewater.
The aim of the study was to investigate the application of photocatalytic advanced oxidation (PAO... more The aim of the study was to investigate the application of photocatalytic advanced oxidation (PAO) for the treatment of water contaminated with dark humic material from fynbos biome plants, which cannot be treated by conventional methods. The study used a fynbos species (Aspalathus linearis) to create a model wastewater that was compared with a brew made from black tea (Camellia sinensis). Two photocatalysts (TiO2 and ZnO) and three light sources (natural, halogen light, and UV light) were tested, with and without hydrogen peroxide. The treatment of the two teas by only photolysis was observed to be minimal. The study found that natural sunlight was not effective, but a combination of ZnO and halogen lamp exhibited the best performance, with a 60% degradation in 20 min under solar irradiation. The optimum catalyst concentration was identified as 10 g/L for both photocatalysts. The influence of some process parameters showed that a combination of an optimum dose of 5 mM H2O2 and sola...
There are currently no studies on the synthesis and fabrication of ZnO-BiOI and ZnO-WO3 heterojun... more There are currently no studies on the synthesis and fabrication of ZnO-BiOI and ZnO-WO3 heterojunctions for the photocatalytic destruction of 2-chlorobiphenyl.
Comparative analysis of the shallow and deep aquifers of Nsukka SE, Nigeria was studied as a prel... more Comparative analysis of the shallow and deep aquifers of Nsukka SE, Nigeria was studied as a preliminary approach for the underground water resource development of the region. Method of approach involves the identification of rock formations and delineation of their stratigraphic relationships. Activities involved collection and analysis of water samples from boreholes and hand dug wells. A total of 14 water samples were collected (7 from shallow and deep aquifer each) and analyzed for inorganic and organic components. Ca 2+, Na + , Mn 2+ , Cl - , Pb and Cd were analyzed using Atomic absorption spectroscopy. K + was determined using flame photometer method. Copper Cu 2+ was analyzed using spectrophotometer, pH was analyzed with the aid of pH meter, Fe 2+ was determined calorimetrically using Spekker absorption meter; Tds was determined using glass fiber filter. Turbimetric method was used to assess turbidity. Anions like HCO 3 - were also estimated by titrimetric method. ...
Saline intrusion has been a major source of groundwater contaminant in coastal regions. The situa... more Saline intrusion has been a major source of groundwater contaminant in coastal regions. The situation has adversely affected groundwater quality . Being an essential source of freshwater for the teeming population over the world and indeed Nigeria and its suitability for various uses is largely dependent on physico-chemical quality, this study therefore selected for its quality assessment, the coastal aquifer of Buguma in rivers state Nigeria. Water samples collected from various locations using systematic random sampling were subjected to physico-chemical analysis . sodium (Na 2+ ) (288mg/l) chloride(Cl - )(414.7mg/l) and nitrate (N03-)(64.45 mg/l) ions dominated the major ions of sample results and also exceeded the Nigerian Standard for Drinking Water Quality NSDWQ 2007 and WHO drinking water standard 2006. Among the trace elements, Fe 2+ and As ions were above the drinking water regulatory limits of NSDWQ and WHO. Classification techniques were employed to provide an...
British Journal of Applied Science & Technology, 2016
Industrialization has been the major source of waste generation leading to heavy metal accumulati... more Industrialization has been the major source of waste generation leading to heavy metal accumulation in soils. It has become major environmental challenge especially as it affects soil quality, biota, ecosystem processes and ground water pollution. This study was targeted at determining the contributions of human activities on heavy metal levels of soils in Owerri, eastern Nigeria, by applying Index of geo-accumulation (I-geo) and Contaminant factor (Cf) models on heavy metal levels at major locations. Soil samples were collected during the rainy season with the aid of a hand-dug soil auger (2.50 cm diameter) from three different composite sites: refuse dumps, auto-mechanic villages and a control sample from a virgin land at depths of 0-15 cm, 15-30 cm and 30-45 cm respectively. These were subjected to standard chemical analyses. There were significant variations (P<0.05) in heavy metals concentrations at different depths. There were no significant variations (P>0.05) in pH. pH (5.9-5.2) was acidic at different soil depths, which might Original Research Article Ihejirika et al.; BJAST, 12(1): 1-9, 2016; Article no.BJAST.19357 2 favor ionization of metals; electrical conductivity at the contaminated sites was higher (300.4-248.4 μs/cm) than at the control site (195.8-150.6 μS/cm) which might imply high concentration of ionized dissolved chemicals from waste dumpsites. Copper (Cu) from contaminated areas ranged from 19.1-16.4 mg/kg against control value that was insignificant (P>0.05); Lead (Pb) ranged from 58.228.2 mg/kg against 0.4-0.2 mg/kg; Iron (Fe) ranged from 5.6-2.6 mg/kg against 5.6-2.6 mg/kg; Zinc (Zn) ranged from 140.3-119.4 mg/kg against 3.3-2.5 mg/kg of control. I-geo for all metals fell in the categories of 4-5 and >5. All categories with values within 4-5 were soils that were highly polluted to very highly polluted, while those with values greater than 5 were soils that were very highly polluted. The Cf values of metals were quite >1.5 which implied that the activities at the mechanic villages and waste dumpsites contributed significantly to the heavy metal burden of the soils. Anthropogenic impacts on heavy metal levels on the samples were between 97.6 and 99.9%. Anthropogenic activities should be controlled to prevent heavy metal pollution of soils and sustain quality soil health.
Adsorption of Fe 3+ /Fe 2+ from a polluted shallow well water onto a palm kernel shell activated ... more Adsorption of Fe 3+ /Fe 2+ from a polluted shallow well water onto a palm kernel shell activated carbon (PKSAC) has been studied. Batch experiment was adopted to study the Removal efficiency of Fe 3+ /Fe 2+ on varying contact time, temperature, adsorbent loading and concentrations. Equilibrium isotherm and kinetic were also studied. Removal efficiency progressed with contact time till the peak adsorption time of 100 minutes when the efficiency remained at equilibrium. Also, removal efficiency got to equilibrium at the peak values of 80oC, 4.8g and 12.5mg/l for temperature, adsorbent loading and concentration variations respectively. The adsorption isotherm models fitted the isotherm data got at 25oC, 40oC and 80oC in this order; Langmuir > Temkin>Freunlich. The dimensionless separation factor of 0.012, 0.017 and 0.015 for 25oC, 40oC and 80oC respectively confirmed favorable adsorption of Fe 3+ /Fe 2+ on the PKSAC adsorbent. Langmuir adsorption capacity increased from 203.9mg Fe 3+ /Fe 2+/ g to 389.3 mg Fe 3+ /Fe 2+/ g when the temperature increased from 25oC to 40oC but decreased to 308.1 mg Fe 3+ /Fe 2+/ g at Original Research Article American Chemical Science Journal, 4(3): 298-325, 2014 299 temperature of 80oC. The kinetic models described the kinetic study data got at 25oC, 40oC and 80oC as follows; power-function>second-order>Elovick>intra-diffusion>first-order kinetics. Mass transfer through liquid film diffusion controlled the adsorption of Fe 3+ /Fe 2+ onto PKSAC. Negative values of the Thermodynamic parameters (∆ , ∆ and ∆ ) got at various temperature values showed favorability of adsorption of Fe 3+/ Fe 2+ onto PKSAC. It is therefore concluded that PKSAC removed Fe 3+/ Fe 2+ from aqueous solution.
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