[Effects of perfluorooctane sulfonate on acute lethality and avoidance behavior of earthworm].

As a new kind of persistent organic pollutants, perfluorooctane sulfonate (PFOS) has become a research spot of environmental science and toxicology. Its impacts on ecological environment should be deeply studied. In this paper, standard contact filter paper test of OECD, artificial soil test, and natural soil test were adopted to study the effects of PFOS on the acute lethality and avoidance behavior of earthworm. The results showed that the acute toxicity of PFOS on earthworm was related to the toxicant exposure time and concentration. The LC50, 48 h in filter paper test, LC50,14 d in artificial soil test, and LC50, 14 d in natural soil test were 13.64 microg x cm(-2), 955.28 mg x kg(-1), and 542.08 mg x kg(-1), respectively. At the maximum test concentration of 160 mg x kg(-1), the earthworm in artificial soil and natural soil showed significant avoidance behavior, which proved that earthworm could perceive and avoid the soil contaminated by a higher concentration of PFOS. To assess PFOS-contaminated soils, the avoidance endpoint was more sensitive than the mortality endpoint. PFOS had higher acute toxicity on earthworm in natural soil than in artificial soil. Meanwhile, more significant avoidance reaction was observed in natural soil than in artificial soil at the same concentrations of PFOS.

Spectroscopic investigations of the chiral interactions between lipase and the herbicide dichlorprop.

The enantioselective interaction between penicillium expansum alkaline lipase and chiral phenoxypropionic acid herbicide dichlorprop was studied by using UV differential spectrophotometry and fluorescence spectrophotometry in the presence of a pH 8, phosphate buffer solution. Chiral differences in the UV absorption and fluorescence spectra of lipase with dichlorprop were detected. (R)-Dichlorprop interacted the strongest with lipase as measured by both UV absorption and fluorescence spectrophotometry, followed by (Rac)-dichlorprop, while (S)-dichlorprop had the weakest interaction. The hydrophobic interaction seem to play the dominant role in the interactions and the (R)-enantiomer needed the minimum put of energy to drive the endothermic reaction, while the Rac-type and S-type compounds needed more for the reaction to take place. In the meantime, the catalytic hydrolysis of FDA with lipase show that (R)-DCPP could inhibit lipase the most strongly relatively at the same condition, perhaps because (R)-DCPP had a stronger combining effect and high enantiomeric selectivity on lipase than (Rac)-DCPP and (S)-DCPP.

Removal of terephthalic acid in alkalized wastewater by ferric chloride.

Terephthalic acid, which is a main component in alkali-decrement wastewater, is efficiently removed using ferric chloride in high pH solutions. About 90% removal of terephthalic acid is achieved at pH between 8 and 11. Especially, the removal reached 94.3% at pH 11. However, as the pH increased from pH 12 and 13, the low removal of terephthalic acid were found. The increasing ferric chloride dosage had a dramatic positive impact on the achieved removal of terephthalic acid. Further increase in the ferric chloride dosage did not produce better removal rate. The increase of terephthalic acid concentration also led to the increase of ferric chloride dosage in order to get the same removal of terephthalic acid. There was approximately a negative linear relationship between terephthalic acid concentration and removal of terephthalic acid. Compared with other coagulants, it can be seen that ferric chloride is more effective in a high pH solution and the amount of ferric chloride required is also less as compared with aluminum chloride, magnesium chloride and calcium chloride. Our results clearly showed that terephthalate anions strongly binds to positive Fe(OH)(3) flocs and forms insoluble complexes, probably through a mechanism involving electrostatic attraction. The electrostatic attraction may be particularly useful means of purifying wastewater in high pH solutions.

Effects of beta-cyclodextrins on the enzymatical hydrolysis of chiral dichlorprop methyl ester.

The effect of beta-cyclodextrins (beta-CDs) on the enzymatical hydrolysis of chiral dichlorprop methyl ester (DCPPM) was studied. Four kinds of beta-cyclodextrins (beta-cyclodextrin, Partly methylated-CD (PM-beta-CD), hydroxypropyl-cyclodextrin (HP-beta-CD) and carboxymethyl-cyclodextrin (CM-beta-CD)) were used. Compared with 100% DCPPM in the absence of betacyclodextrins, the activity of lipase decreased with the increase of Pbetacyclodextrin and PM-Pbetacyclodextrin. However, CM-beta-clodextrin stimulated the lipase activity. The inhibition effect of Pbeta cyclodextrin and PM-5betacyclodextrin on the hydrolysis of DCPPM is affected by many factors other than degree of the methylation blocking the active site of lipase. UV-Vis and Fourier transform infrared (FTIR) spectroscopy studies of the complexation of aqueous DCPPM with beta-CDs provide fresh insight into the molecular structure of the complex and explain the effects of beta-CDs on enzymatical hydrolysis of chiral DCPPM. Data showed that inclusion complexes had formed by complexation of the CM-beta-CD with DCPPM and the solubility of DCPPM was increased in water, which lead to the increased lipase activity.

Effects of adsorption interferents on removal of Reactive Red 195 dye in wastewater by chitosan.

Reactive Red 195, which is an azoic anionic dye characterized by the presence of five sulfonic groups and one azoic group, is efficiently removed using chitosan. The increasing chitosan dose had a dramatic positive impact on the achieved color removal, there was approximately a linear relationship between chitosan dose and color removal of dye before color removal reach maximum. Also, the increase of dye concentration led to the increase of chitosan dosage in order to get the same color removal. 92 mg/L of chitosan dosage was sufficient to achieve complete remove of dye at initial concentration of dye at 200 mg/L. For the higher concentrations of dye, high dosages were necessary to reach complete color removal. On the other hand, the use of adsorption interferents (Fe2+, Na+, HCO3- and others) can be interesting, addition of ions had effect on the color removal of Reactive Red 195. Comparing with blank, addition of chemical species approximately decreased the color removal except Na+ and combination of Fe2+ + HCO3-. However, comparing with Fe2+ alone and HCO3- alone, combination of Fe2+ + HCO3- increased the color removal.

[Enantioselective degradation of 2, 4-dichlorprop methyl ester by sediment bacteria].

Enantioselective Degradation of 2,4-Dichlorprop methyl ester was studied by sediment bacteria. One DCPPM-degrading bacteria stain was isolated from contaminated sediments. The EF values were determined by chiral GC. The enantioselectivity of DCPPM biodegradation in aquatic phases were evaluated. Incubation with DCPPM-degrading bacteria show that the R enantiomer was preferentially degraded over the corresponding S enantiomer of DCPPM. The EF values show a much higher deviation. It indicate that the microbial degradation of DCPPM was enantioselectivety.

Influence of kaolinite on chiral hydrolysis of methyl dichlorprop enantiomers.

The effect of kaolinite on the enzymatic chiral hydrolysis of methyl dichlorprop enantiomers ((R,S)-methyl-2-(2,4- dichlorophenoxy) propanoic acid, 2,4-DPM) was investigated using chiral gas chromatography. Compared with the control without kaolinite, the enantiomeric ratio (ER) increased from 1.35 to 8.33 and the residual ratio of 2,4-DPM decreased from 60.89% to 41.55% in the presence of kaolinite. Kaolinite likely had emotion influence on lipase activity and its enantioselectivity. Moreover, the amount of kaolinite added was also found to be a sensitive factor affecting the enantioselective hydrolysis of 2,4-DPM. Fourier transform infrared (FTIR) spectroscopy studies of the interaction of lipase with kaolinite provided insight into the molecular structure of the complex and offered explanation of the effects of kaolinite on enzymatic hydrolysis of 2,4-DPM. Spectra showed that the effect of kaolinite on the hydrolysis of 2,4-DPM was affected by adsorption of lipase on kaolinite and changes of adsorbed lipase conformation, which led to the modified enantioselectivity.

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.

Effects of bifenthrin on Daphnia magna during chronic toxicity test and the recovery test.

The acute and chronic toxic effects of bifenthrin on Daphnia magna were studied. The results showed that 24 h-EC50, 48 h-LC50 and 96 h-LC50 of bifenthrin on D. magna were 3.24, 12.40 and 1.40 microg/L respectively. And the LOEC and NOEC of bifenthrin were 0.02 and 0.004 microg/L respectively. The recovery test of bifenthrin on Daphnia magna was presented. Daphnia magna (F0 generation) were exposed during 21 d to different bifenthrin concentrations. Offspring (animals from the first and third brood: F1 (1st) and F1 (3rd), respectively) were transferred to a free pesticide medium during a 21 d recovery period. In this recovery study, survival, growth, reproduction (mean total young per female, onset of reproduction and number broods per female) and the intrinsic rate of natural increase (r) were assessed as parameters. Reproduction such as number of young per female as well as length was still reduced in F1 (1st) generation daphnids from parentals (F0) exposed to the bifenthrin. However F, (3rd) individuals from parentals exposed to pesticide concentrations were able to restore reproduction when a recovery period of 21 d was allowed, but the length of F, (3rd) from parentals exposed to the 0.5 and 0.75 microg/L bifenthrin concentration was still significantly effected (P < 0.05).

Photochemistry of insecticide imidacloprid: direct and sensitized photolysis in aqueous medium.

The direct and sensitized photodegradations of imidacloprid, 1-(6-chloro-3-pyridinylmethyl)-N-nitro-2-imidazolidinimine, were investigated in aqueous solution and with and without various photo-sensitizers. Results of the study revealed that the intensity of lamp-house and irradiation wavelength had significant effects on the photolysis of imidacloprid. Complete degradation of 20 mg/L imidacloprid in aqueous phase was observed in 40 min under ultraviolet( UV) irradiation system, suggesting the ultraviolet ray played significant role in direct photolysis of imidacloprid. The additions of various photo-sensitizers lead to improve the degradation efficiency of imidacloprid under the irradiation of black light fluorescent lamp. TiO2 was the most efficient in the photo-catalytic degradation of imidacloprid among other photo-sensitizers in used this study. However, addition of acetone inhibited the photolysis of imidacloprid under the irradiation of UV, indicating the occurrence of competition between acetone and imidacloprid for photos. Mineralization of the imidacloprid was examined to clarify the final photochemical degradation products of the insecticide which were CO2, Cl- and NO3-. Complete photo-oxidation of nitrogen to NO3- occurred very slowly via the intermediate formation of NH4+ and NO2-.

Cleaner and convenient preparation of 3-(4,6-dimethoxy-pyrimidin-2-yloxy)-2-methyl-phenol.

Environmental concerns have highlighted the need of cleaner technologies. A cleaner, convenient and selective technology has been developed for the preparation of 3-(4,6-dimethoxy-pyrimidin-2-yloxy)-2-methyl-phenol (DPMP) from 2-methyl-benzene-1,3-diol in water as solvent. The isolated yield of DPMP is up to 86% in good selectivity. The product structure was characterized by conventional methods, 1H-NMR and MS. This technology belongs to the modern concept of environmentally friendly low wastes or non-wastes technology (LWNWT).