[Preparation of Catalyst Cyclodextrin-Fe-TAML to Activate H2O2 and Oxidize Organic Micropollutants in Water].

In order to improve the stability and catalytic activity of Fe-TAML, mono-6-oxy-cyclodextrin bonded Fe-TAML catalyst (CD-Fe-TAML) was prepared by bonding Fe-TAML with cyclodextrin (CD) through chlorosulfonylation reaction, metal chelation reaction, and nucleophilic substitution reaction. The catalytic activity and stability of CD-Fe-TAML and the oxidation degradation efficiencies of 34 organic micropollutants such as antibiotics and pesticides by activation of H2O2in water were studied. Compared with that of Fe-TAML, CD-Fe-TAML at pH 7.0 had a 49-fold and 25-fold increase in the rate of activating H2O2 to produce iron (Ⅴ/Ⅳ)-oxo intermediates and the degradation rate of the substrate, respectively, and its self-oxidation rate was reduced by 70%. The stability of CD-Fe-TAML was 0.7-699 times higher than that of Fe-TAML in the pH range of 3.0-10.0. Specifically, the stability of CD-Fe-TAML was 33-699 times higher than that of Fe-TAML in the pH range of 3.0-7.0. The sulfonic acid group in the molecular structure of CD-Fe-TAML had an electrophilic effect, which could increase the positive charge density of Fe in the active center, accelerate the O-O bond cleavage of H2O2 and the generation of iron(Ⅴ/Ⅳ)-oxo intermediates, improve the catalytic activity of Fe-TAML, and also improve its hydrolysis stability. Meanwhile, the CD group in the molecular structure had the "electron shuttle" effect and inclusion effect. The former could accelerate the electron transfer between the active center Fe-TAML and H2O2 to improve the catalytic activity of Fe-TAML. The latter could inhibit the hydrolysis and self-oxidation of the active center Fe-TAML by inclusion or binding of the hydrolysis sites and oxidation sites, thus improving its stability. The degradation efficiencies of micropollutants by CD-Fe-TAML/H2O2 under weakly acidic and neutral conditions (in the pH range of 5.0-7.0) were 0.4-59 times higher than those of Fe-TAML/H2O2. The degradation efficiencies of CD-Fe-TAML/H2O2 on nine micropollutants with a molar volume less than 0.20 L·mol-1, such as acetamiprid and sulfadiazine, were 0.3-1.1 times higher than that of Fe-TAML/H2O2 at pH 8.0, and there were no significant differences between CD-Fe-TAML/H2O2 and Fe-TAML/H2O2for micropollutants with a molar volume greater than 0.20 L·mol-1. The results of iodide oxidation by CD-Fe-TAML/H2O2 showed that I- was not oxidized to produce iodo-disinfection byproducts (I-DBPs). The degradation of micropollutants by CD-Fe-TAML/H2O2 in the surface water sample was not disturbed by water components. The CD-Fe-TAML/H2O2 system has a potential application in the removal of organic micropollutants from water.

[Characterization of napropamide enantiomers by CD and determination of the enantiomeric ratios in water].

The enantiomers of napropamide were separated by normal phase HPLC (HPLC: high performance liquid Chromatography) with Chiralpak OJ-H column and charactered by circular dichroism. On this basis, a method for the chiral separation and micro-determination of napropamide in water was established. The linearity of calibration curve for racemic mixture was 10-100 ng x mL(-1) and the correlation coefficient was 0. 99. When 10 microL was injected, the detection limit of racemic mixture was 8 ng mL(-1), and the detection limits of both enantiomers were 4 ng x mL(-1).

Effects of methyl-CD and humic acid on hydrolytic degradation of the herbicide diclofop-methyl.

Hydrolytic degradation of the herbicide diclofop-methyl was investigated in the multi-pH deionized water, natural aquatic systems and soil suspensions. Resulting data indicated that the herbicide was stable in the acidic and nearly neutral solutions for at least 15 d. The herbicide diclofop-methyl rapidly dissipated in the natural aquatic systems and soil suspensions with half-lives less than 4 d. Methyl-CD (partially methylated beta-cyclodextrin) improved its hydrolytic degradation in the pH 8 deionized water and natural aquatic systems while humic acid inhibited its hydrolytic degradation at the same conditions. But dissolved organic matter in the natural aquatic systems and soil suspensions increased its hydrolysis. Two catalysis mechanisms were introduced to describe the effects of cyclodextrin and organic matter on its hydrolytic metabolism. Though inorganic ions maybe improved its hydrolysis reaction in the natural aquatic systems, Fe2+ and Cu2+ did not form complexes with the herbicide and had poor influences on its hydrolytic degradation whether cyclodextrin was added or not.

[Simultaneous determination of four-components in mixed herbicides by modified target factor analysis-UV spectrophotometry].

In this paper, the modified target factor analysis-UV spectrophotometry method is established for simultaneous determination of paraquat CL, cyanzine, metolachlor and atrazine in mixed herbicides. The experimental results show that the recovery of each herbicide by MTFA is more accurate than by TFA. The recovery of paraquat CL ranges from 99.47% to 102.02%, of cyanzine 98.93%-102.75%, of metolachlor 98.13%-102.65% and of atrazine 97.42%-103.20%, with SD for the four components to be 1.16%, 1.84%, 1.84% and 2.55% respectively. All in all, the modified target factor analysis method can be used to determine accurately mixed herbicides which exhibits intrinsic interaction among components.

[Application of automated identification and quantification system with a database (AIQS-DB) to screen organic pollutants in surface waters from Yellow River and Yangtze River].

Approximately 1 000 chemicals were screened in surface waters from downstreams of Yellow River and Yangtze River using GC-MS coupled with Automated Identification and Quantification System with a Database (AIQS-DB). 95 pollutants were detected in water samples from Yellow River in Shandong Province and 121 in those from Yangtze River in Jiangsu Province. The pollutants involved n-alkanes, PAHs, phenols, nitro compounds, phthalates esters (PAEs), pesticides and pharmaceuticals, etc. The average concentrations of n-alkanes, 16 priority PAHs and 6 priority PAEs were 1 806 ng/L, 27 ng/L, 77 ng/L in water samples from Yellow River and 720 ng/L, 30 ng/L, 2 166 ng/L in water samples from Yangtze River respectively. Besides, 9 and 11 pesticides were detected in water samples from Yellow River and Yangtze River respectively. The levels of pollutants showed stronger site dependence in samples from Yellow River than those from Yangtze River. Combination of GC-MS and AIQS-DB shows high efficiency in regional pollutants survey.

[Enhanced sorption of OTC on clays via complexation with Zn2+].

Oxytetracycline (OTC) and Zn2+ are both widely used as growth promoters in concentrated animal feeding operations, which are discharged into soil system by manure application. There is special environment significance to study the sorption and interaction of OTC with accompanied metal cations on clays to elucidate their environmental behaviors and to assess ecological risks. Much stronger sorption of OTC was observed on montmorillonite than that on kaolinite, which might be resulted from the larger cation exchange capacity of the former. Different pH-dependent Kd patterns were illustrated on montmorillonite and kaolinite, which might be contributed by the different properties of surface charge. During 4 < pH < 5, OTC sorption was decreased by cation competition of Zn2+, while OTC sorption was promoted by OTC-Zn-clay bridge while 5 < pH < 9, and the most significant effect was shown at pH = 6.5. The sorption of Zn2+ on two clays was decreased by OTC in the pH range studied, which can be explained by cation competition of OTC at lower pH, or by prohibition in the sorption or precipitation resulted from complexation between OTC and Zn2+ at higher pH. CD and UV-Vis spectrometry analysis showed that there was no complexation observed between OTC and Zn2+ at pH = 4. But with increasing of pH value, complexation might happen at the sites of O11, O12 or O12, O1.

[Prediction of common buffer catalysis in hydrolysis of fenchlorazole-ethyl].

The purpose of this study was to elucidate the effects of temperatures, pH levels and buffer catalysis on the hydrolysis of FCE. The hydrolysis of FCE follows first-order kinetics at different pH levels and temperatures. FCE hydrolysis rates are greatly increased at elevated pH levels and temperatures. The maximum contribution of buffer catalysis to the hydrolysis of FCE was assessed based on application of the Bronsted equations for general acid-base catalysis. The results suggest that the buffer solutions play an obvious catalysis role in hydrolysis of FCE and the hydrolysis rates of FCE are quickened by the buffer solutions. Besides, the buffer catalysis capacity of different buffer solutions is diverse, and the buffer catalysis capacity at different pH levels with the same buffer solutions is different, too. The phosphate buffer at pH = 7 shows the maximal buffer catalysis capacity. The hydrolysis rate constants of FCE as a function of temperature and pH, which were remedied by the buffer catalysis factor, were mathematically combined to predict the hydrolytic dissipation of FCE. The equation suggests that the hydrolysis half-lives of FCE ranged from 7 d to 790 d. Hydrolysis metabolites of FCE were identified by liquid chromatography-mass spectrometry. In basic conditions (pH 8-10), fenchlorazole was formed via breakdown of the ester bond of the safener.