Ethion residue removal efficiency using individual and combined effects of ultrasonication (US), ozonation (O3), ultrasonication and ozonation (US/O3) was investigated. A 1 mg·L-1 standard ethion was subjected to...Ethion residue removal efficiency using individual and combined effects of ultrasonication (US), ozonation (O3), ultrasonication and ozonation (US/O3) was investigated. A 1 mg·L-1 standard ethion was subjected to an ultrasonic irradiation (3W input power) device with different frequencies of 108, 400, 700, 1000 kHz, and to an ozone with a concentration of 200 mg· mL-1 with various exposure times (0, 15, 30, 45 and 60 minutes). Reduction of residual ethion was determined by gas chromatography with flame photometric detection (GC-FPD). It was found that 1000 kHz ultrasonic irradiation for 60 minutes was the most effective treatment for reducing ethion concentration. Additionally, ozone could reduce the concentration of standard ethion after 60 minutes of exposure. Ultrasonic irradiation in combination with ozone had a synergistic effect in reducing standard ethion concentration, with the highest rate occurring within the first 15 minutes. Ethion concentration was reduced to 75.43% after ultrasonic irradiation at 1000 kHz and ozone exposure for 60 minutes. The effectiveness of the combined scheme for reducing of ethion residues on tangerine was also determined by GC-FPD. The ethion residue on fresh tangerines after ultrasonic irradiation and ozone washing was reduced by 73.03% after 60 minutes. The present study demonstrates that ultrasonic irradiation and ozone exposure could be used to reduce ethion residues in treated tangerine in order to meet the Standards for Pesticide Residue Limits.展开更多
Geosmin is one of the major causative compounds of earthy-musty odor and taste (off-flavor) in drinking water (lakes) and in farmed fish. In this study, the sorption of cyclodextrin polymers (CDPs) towards geosmin in ...Geosmin is one of the major causative compounds of earthy-musty odor and taste (off-flavor) in drinking water (lakes) and in farmed fish. In this study, the sorption of cyclodextrin polymers (CDPs) towards geosmin in aqueous solution was investigated. Sorption kinetics, the effect of solution pH and contact time on the sorption capability of α-, β- and γ-cyclodextrin polymers was discussed. Results disclosed that the sorption of geosmin by the CDPs followed the Ho and McKay kinetic mechanism with the liquid film diffusion as the rate-determining step. Both β-CDP and γ-CDP exhibit high removal efficiencies of 93.4% and 96%, respectively, within 240 minutes at 25°C and pH 7, whilst α-CDP was not effective, removing only 40% geosmin, at an initial concentration of 5 μg·L—1and 5 g·L—1of CDP dose. The cyclodextrin polymers can adapt to a wide range of pH from 3.0 to 11.0 for geosmin adsorption with pH 7.0 as optimum. Results indicate that these sorbents demonstrate significant potential in reducing the concentration of geosmin in water that presents taint problems in both drinking water and fish.展开更多
文摘Ethion residue removal efficiency using individual and combined effects of ultrasonication (US), ozonation (O3), ultrasonication and ozonation (US/O3) was investigated. A 1 mg·L-1 standard ethion was subjected to an ultrasonic irradiation (3W input power) device with different frequencies of 108, 400, 700, 1000 kHz, and to an ozone with a concentration of 200 mg· mL-1 with various exposure times (0, 15, 30, 45 and 60 minutes). Reduction of residual ethion was determined by gas chromatography with flame photometric detection (GC-FPD). It was found that 1000 kHz ultrasonic irradiation for 60 minutes was the most effective treatment for reducing ethion concentration. Additionally, ozone could reduce the concentration of standard ethion after 60 minutes of exposure. Ultrasonic irradiation in combination with ozone had a synergistic effect in reducing standard ethion concentration, with the highest rate occurring within the first 15 minutes. Ethion concentration was reduced to 75.43% after ultrasonic irradiation at 1000 kHz and ozone exposure for 60 minutes. The effectiveness of the combined scheme for reducing of ethion residues on tangerine was also determined by GC-FPD. The ethion residue on fresh tangerines after ultrasonic irradiation and ozone washing was reduced by 73.03% after 60 minutes. The present study demonstrates that ultrasonic irradiation and ozone exposure could be used to reduce ethion residues in treated tangerine in order to meet the Standards for Pesticide Residue Limits.
文摘Geosmin is one of the major causative compounds of earthy-musty odor and taste (off-flavor) in drinking water (lakes) and in farmed fish. In this study, the sorption of cyclodextrin polymers (CDPs) towards geosmin in aqueous solution was investigated. Sorption kinetics, the effect of solution pH and contact time on the sorption capability of α-, β- and γ-cyclodextrin polymers was discussed. Results disclosed that the sorption of geosmin by the CDPs followed the Ho and McKay kinetic mechanism with the liquid film diffusion as the rate-determining step. Both β-CDP and γ-CDP exhibit high removal efficiencies of 93.4% and 96%, respectively, within 240 minutes at 25°C and pH 7, whilst α-CDP was not effective, removing only 40% geosmin, at an initial concentration of 5 μg·L—1and 5 g·L—1of CDP dose. The cyclodextrin polymers can adapt to a wide range of pH from 3.0 to 11.0 for geosmin adsorption with pH 7.0 as optimum. Results indicate that these sorbents demonstrate significant potential in reducing the concentration of geosmin in water that presents taint problems in both drinking water and fish.
