[Red Mud-activated Peroxymonosulfate for Ciprofloxacin Degradation: Efficiency and Mechanism].

In this paper, the effects and mechanism of ciprofloxacin (CIP) degradation with peroxymonosulfate (PMS) catalyzed by solid waste red mud (RM) was firstly studied. The results indicated that RM has large specific surface area (10.96 m2·g-1) and complex pore structure, containing ferric, alumina and calcium oxide, which enhanced ciprofloxacin degradation by PMS effectively. Radical quenching experiments revealed that SO4-·and HO·were contributed to ciprofloxacin oxidation, and the reaction was mainly occurred on RM's surface. An increase in temperature could accelerate CIP degradation, and the corresponding reaction activation energy Ea was about 5.74 kJ·mol-1. Meanwhile, CIP degradation rate increased with PMS concentration and the optimal dosage of RM was 1.0 g·L-1. Eight degradation intermediates were identified using HPLC/MS/MS, and consequently, CIP was degraded mainly through two pathways; the piperazine groups were preferentially attacked by active free radicals. This study further indicated that RM is a cheap catalyst and can be potentially used in the treatment of antibiotic contaminated wastewater.

[Molecular weight fractionated characterization of dissolved organic matter and its correlation with water quality in the Bahe River Basin, Northwest China]. / çžæ²³æµåŸŸæº¶è§£æ€§æœ‰æœºè´¨åˆ†å­é‡åˆ†çº§è¡¨å¾åŠå ¶ä¸Žæ°´è´¨çš„ç›¸å ³æ€§.

Dissolved organic matter (DOM) is one of the core carriers of organic matter decomposition and nutrient regeneration in water. It is an important link of biogeochemical cycle of carbon and nitrogen, and the key content of water environmental science research. We used liquid chromatography-organic carbon detection-organic nitrogen detection (LC-OCD-OND) to investigate the molecular weight distribution of riverine DOM in the Bahe River of Xi'an City and further analyzed its correlation with water quality. The results showed that riverine DOM was composed of biopolymers, humic substances, humus degradation products, and low molecular-weight neutrals, with the ave-rage concentration of 0.15, 1.75, 0.48, 0.36 and 0.002 mg·L-1, respectively. The DOM along the river was in order of urban＞ town＞ river source. The humic substances with molecular weight of 1000-20000 Da accounted for 49.0% of total DOM which followed the order of town＞ waste water treatment plants (WWTPs) effluents＞river estuary＞ river source. The biopolymers with the molecular weight of >20000Da accounted for 5.1% of total DOM, with the sequence of WWTPs effluents＞river estuary＞river source＞town. The allochthonous (terrigenous) DOM produced by WWTPs effluents had the greatest contribution to the riverine DOM. The fractions of DOM with different molecular weights had significant correlations with water quality parameters. The results showed that the molecular weight fractions and abundance of DOM based on LC-OCD-OND could be used as a comprehensive index for water quality monitoring, to characterize the spatial heterogeneity of river water quality, and used for quantitative identification and source apportionment of pollutant components.

[Progress in the Studies of Precipitation Chemistry in Acid Rain Areas of Southwest China].

The precipitation data for nine sites in the acid rain area of southwest China were analyzed. The data included pH and the concentrations of major ions (Cl-, SO42-, NO3-, Ca2+, NH4+, Mg2+, K+, and Na+). SO42- and NO3- were the main anions, whereas Ca2+ and NH4+ were the main cations in the precipitation. The concentrations of acidic ions, alkaline ions, and total ions in this area were significantly higher than those reported in southeast China, but much lower than those in northern China. About 58% of the total precipitation has a pH value ranging from 4.5 to 5.6. According to the correlation of acidic and alkaline ions as well as the results of the neutralization factor, the rainwater in this area has been neutralized. Ca2+ and NH4+ are the dominant neutralization substances in rainwater. Comparisons of pH and the main ion components with other areas showed that rainfall neutralization in this area was stronger than that in southeast China but poorer than that in northern China. Calculation of enrichment factors for rainwater components relative to soil and seawater indicated that Ca2+ and Mg2+ mainly originated from terrestrial sources and SO42- and NO3- were mostly attributed to the anthropogenic activities in this area. In addition, approximately 99.7% of Ca2+ and 84.0% of Mg2+ were attributed to terrestrial sources and were closely related to the widespread distribution of carbonate rocks in the southwest of China.

[Transport kinetics of Pb(II) through bulk liquid membrane using PC-88A as carrier].

The effects of stirring speed, carrier concentration and reaction temperature on the transport of Pb(II) ion through bulk liquid membrane were studied with chloroform as membrane solvent and 2-ethylhexyl phosphonic acid-mono-2-ethylhexylester as carrier. The Pb(II) ions concentrations of feed phase and stripping phase were assayed by atomic absorption spectroscopy. The kinetic parameters, including apparent rate constants of Pb(II) ion extraction and re-extraction reactions, the maximum concentration of Pb(II) ion in the liquid membrane, the time of the maximum value of maximum concentration of Pb(II) ion in the liquid membrane and the maximum entry and exit fluxes of Pb(II) ion through the liquid membrane of the extraction and stripping reactions, were evaluated. The apparent activation energy value is 31.65 kJ x mol(-1) for extraction and 23.11 kJ mol(-1) for stripping. The results indicate that good agreement between experimental data and theoretical predictions could be achieved and the kinetics of Pb(II) transport could be evaluated by two consecutive irreversible pseudo-first order reactions. In this condition the chemical reaction is a procedure of controlled reaction rates.