[Show abstract][Hide abstract] ABSTRACT: 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.
Journal of Zhejiang University SCIENCE B 11/2005; 6(10):1028-32. · 1.11 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: 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.
Journal of Environmental Sciences 02/2005; 17(2):237-40. · 1.77 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: 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.
Journal of Environmental Sciences 02/2005; 17(5):766-9. · 1.77 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: 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).
Journal of Zhejiang University SCIENCE 09/2004; 5(8):956-9.