The conditions for photocatalytic degradation of ethylenediaminetetraacetic acid (EDTA) in aqueous solution with Fe-doped titanium dioxide (TiO2) were optimized. The degradation efficiencies with Fe-doped TiO2 were be...The conditions for photocatalytic degradation of ethylenediaminetetraacetic acid (EDTA) in aqueous solution with Fe-doped titanium dioxide (TiO2) were optimized. The degradation efficiencies with Fe-doped TiO2 were better, compared with those obtained with bare TiO2 and Pt-doped TiO2. The effect of various experimental factors, such as photocatalytic dosage, temperature, solution pH and light intensity on the photocatalytic degradation of EDTA by Fe-doped TiO2 was investigated. The photocatalytic degradation treatment for the wastewater containing EDTA is simple, easy handling and low cost.展开更多
The present work was done in order to develop and find out suitable conversion methods for coconut husk wastes into value-added products. It is well-known that coconuts husk waste is hydrophobic therefore ethanol with...The present work was done in order to develop and find out suitable conversion methods for coconut husk wastes into value-added products. It is well-known that coconuts husk waste is hydrophobic therefore ethanol with different doses was used as a surfactant to enhance the removal efficiency. Treated samples at different adsorbent amounts, sintering temperatures & sintering time, stirring time, pH, and solution temperatures for color removal of Methylene Blue (MB) & Rhodamine B (RhB) and ammonium concentration were evaluated by using UV-Visible Spectroscopy. At 300°C, results showed complete removal for MB and more than 75% for RhB, whereas removal of ammonium ion reached around 52% when sintering product from husk waste was used. Further investigation was carried out for ammonium ion to understand the desorption kinetic behaviors and isotherm models. Kinetics indicated that desorption of ammonium ion followed pseudo-first order equation. Adsorption thermodynamic parameters such as ΔG, ΔH, and ΔS followed Van’t Hoff plot for adsorption and found to be negative which indicated that the adsorption process for ammonium onto coconut husk was physical, spontaneous and exothermic.展开更多
The indirect photocatalytic reduction of arsenate to arsenite in aqueous solution with titanium dioxide(TiO_2)was investigated with various hole scavengers such as methanol, ethanol, 2-propanol, formaldehyde, acetone,...The indirect photocatalytic reduction of arsenate to arsenite in aqueous solution with titanium dioxide(TiO_2)was investigated with various hole scavengers such as methanol, ethanol, 2-propanol, formaldehyde, acetone,formic acid and acetic acid. Although the direct photocatalytic reduction of arsenate to arsenite with TiO_2 was impossible, an indirect reduction of As(V) was possible in the presence of sacrificial electron donors to form strongly reductive radicals. The addition of ethanol was very effective for indirect photocatalytic reduction of As(V) in aqueous solution with TiO_2 photocatalyst. The indirect photocatalytic reduction rate of As(V) may be related with both the reaction rate constants of reaction of hydroxyl radicals with hole scavenger and the reactivities for the radicals M· which are produced by the reaction of ·OH with hole scavenger.展开更多
The metal-doping into the photocatalyst was evaluated for the photocatalytic degradation of bisphenol A in aqueous solution with ZnO powder. Au/ZnO, Ag/ZnO and Cu/ZnO were tested in the present work. Ag-doping ZnO was...The metal-doping into the photocatalyst was evaluated for the photocatalytic degradation of bisphenol A in aqueous solution with ZnO powder. Au/ZnO, Ag/ZnO and Cu/ZnO were tested in the present work. Ag-doping ZnO was effective for the improvement of efficiency for the photocatalytic degradation of bisphenol A in water. The optimum doping concentration of silver was found to be 3 wt%. The pseudo first-order rate constant with 3 wt% Ag/ZnO was 1.3 times better compared with bare ZnO. The photocatalytic degradation of treatment for the wastewater containing bisphenol A is simple, easy handling and low cost.展开更多
The effect of heat treatment for rice husk was investigated on the removal of arsenite in ground water by the adsorption onto the rice husk surface. The heat treatment was performed at the temperature from 80<sup&g...The effect of heat treatment for rice husk was investigated on the removal of arsenite in ground water by the adsorption onto the rice husk surface. The heat treatment was performed at the temperature from 80<sup>o</sup>C to 300<sup>o</sup>C in the closed system under anoxic environment. The continuous adsorption column method was applied for the removal of arsenite. The removal efficiency (75%) with rice husk treated at 150<sup>o</sup>C was better compared to those (54%) obtained with untreated rice husk. Therefore, the heat treatment of rice husk at relatively low temperature was effective for the enhancement of arsenic removal from water. The treatment conditions of As removal from aqueous solution were optimized. The developed treatment technique was applied into the real ground water sample in Bangladesh. The As concentration in sample water after treatment was approximately 18 and 8 μg/L, which was below the WHO guideline value of maximum admissible level of arsenic in ground water for Bangladesh (50 μg/L). The developed technique might become a potential avenue for simple and low cost arsenic removal methods.展开更多
文摘The conditions for photocatalytic degradation of ethylenediaminetetraacetic acid (EDTA) in aqueous solution with Fe-doped titanium dioxide (TiO2) were optimized. The degradation efficiencies with Fe-doped TiO2 were better, compared with those obtained with bare TiO2 and Pt-doped TiO2. The effect of various experimental factors, such as photocatalytic dosage, temperature, solution pH and light intensity on the photocatalytic degradation of EDTA by Fe-doped TiO2 was investigated. The photocatalytic degradation treatment for the wastewater containing EDTA is simple, easy handling and low cost.
文摘The present work was done in order to develop and find out suitable conversion methods for coconut husk wastes into value-added products. It is well-known that coconuts husk waste is hydrophobic therefore ethanol with different doses was used as a surfactant to enhance the removal efficiency. Treated samples at different adsorbent amounts, sintering temperatures & sintering time, stirring time, pH, and solution temperatures for color removal of Methylene Blue (MB) & Rhodamine B (RhB) and ammonium concentration were evaluated by using UV-Visible Spectroscopy. At 300°C, results showed complete removal for MB and more than 75% for RhB, whereas removal of ammonium ion reached around 52% when sintering product from husk waste was used. Further investigation was carried out for ammonium ion to understand the desorption kinetic behaviors and isotherm models. Kinetics indicated that desorption of ammonium ion followed pseudo-first order equation. Adsorption thermodynamic parameters such as ΔG, ΔH, and ΔS followed Van’t Hoff plot for adsorption and found to be negative which indicated that the adsorption process for ammonium onto coconut husk was physical, spontaneous and exothermic.
文摘The indirect photocatalytic reduction of arsenate to arsenite in aqueous solution with titanium dioxide(TiO_2)was investigated with various hole scavengers such as methanol, ethanol, 2-propanol, formaldehyde, acetone,formic acid and acetic acid. Although the direct photocatalytic reduction of arsenate to arsenite with TiO_2 was impossible, an indirect reduction of As(V) was possible in the presence of sacrificial electron donors to form strongly reductive radicals. The addition of ethanol was very effective for indirect photocatalytic reduction of As(V) in aqueous solution with TiO_2 photocatalyst. The indirect photocatalytic reduction rate of As(V) may be related with both the reaction rate constants of reaction of hydroxyl radicals with hole scavenger and the reactivities for the radicals M· which are produced by the reaction of ·OH with hole scavenger.
文摘The metal-doping into the photocatalyst was evaluated for the photocatalytic degradation of bisphenol A in aqueous solution with ZnO powder. Au/ZnO, Ag/ZnO and Cu/ZnO were tested in the present work. Ag-doping ZnO was effective for the improvement of efficiency for the photocatalytic degradation of bisphenol A in water. The optimum doping concentration of silver was found to be 3 wt%. The pseudo first-order rate constant with 3 wt% Ag/ZnO was 1.3 times better compared with bare ZnO. The photocatalytic degradation of treatment for the wastewater containing bisphenol A is simple, easy handling and low cost.
文摘The effect of heat treatment for rice husk was investigated on the removal of arsenite in ground water by the adsorption onto the rice husk surface. The heat treatment was performed at the temperature from 80<sup>o</sup>C to 300<sup>o</sup>C in the closed system under anoxic environment. The continuous adsorption column method was applied for the removal of arsenite. The removal efficiency (75%) with rice husk treated at 150<sup>o</sup>C was better compared to those (54%) obtained with untreated rice husk. Therefore, the heat treatment of rice husk at relatively low temperature was effective for the enhancement of arsenic removal from water. The treatment conditions of As removal from aqueous solution were optimized. The developed treatment technique was applied into the real ground water sample in Bangladesh. The As concentration in sample water after treatment was approximately 18 and 8 μg/L, which was below the WHO guideline value of maximum admissible level of arsenic in ground water for Bangladesh (50 μg/L). The developed technique might become a potential avenue for simple and low cost arsenic removal methods.
