Biomimetic Synthesis Of Nano-MnO₂and Degradation Of Chlorpyrifos By Its Immobilized Enzyme

Than free enzyme immobilized enzyme is more stable、repeatable use and more easily separated from reaction system, thus is widely used in biological catalysis, food industry, environmental restoration and so on. Through enzymes immobilized for improvement the use efficiency of enzyme and reduction the cost; So as to realize the reuse of organophosphate degrading enzyme and improve the stability of the enzyme. At the same time MnO2as an important kind of amphoteric oxide, because of its special of nanometer size effect and good REDOX properties, it has widely applied likes in catalytic、electrode materials and so on, especially as a catalyst for pesticide degradation has a significant role in the aspect of environmental remediation. Based on glycine as a template, nanometer grade manganese dioxide were biomimetic synthesized by hydrothermal method, as a carrier of the immobilized organophosphate degrading enzymes, and studied immobilized enzyme degradation characteristics for organophosphorus pesticide. Using potassium permanganate as the only source of manganese, in nitric acid system nanometer manganese dioxide were biomimetic synthesized by hydrothermal method for glycine template. By Scanning electron microscope (SEM) determine samples morphology、Specific surface area pore size analysis aperture size of samples、Fourier infrared spectrometer (FT-IR) analysis sample molecular bonds and X-ray diffraction (XRD) determine a change in sample crystal morphology. Results show:under90℃for1h water bath synthesis manganese dioxide by Glycine template and KMnO4, SEM show that the MnO2crystal appearance present rod polymerization; XRD results showed that the MnO2mainly is a-MnO2; Nitrogen adsorption show that the MnO2is two-dimensional cylindrical hole structure. Based on characterization results, further in-depth study the formation mechanism of nanometer manganese dioxide.Immobilized organophosphate degradation enzymes with MnO2. FT-IR results showed organophosphate degradation enzyme fixation inside the MnO2two-dimensional cylindrical hole. Respectively investigates the influence of immobilized about buffer pH, temperature, adding enzyme amount, glutaraldehyde concentration, stirring speed and fixed time. Optimization enzyme immobilization influencing factors in the process through the response surface method, and identify three main influencing factors of glutaraldehyde concentration, buffer pH and enzymatic quantity. The results show that glutaraldehyde concentration was15%, buffer pH was7.6and enzyme concentration was10mg, under the condition of immobilized enzyme activity increase by6.4%.Studied immobilized enzyme enzymology properties and the degradation of organophosphorus pesticide. After immobilization by MnO2, the thermal stability、pH stability、fastness and continuous reaction ability about free enzyme are improved. Immobilized enzyme has good degradation effect for organophosphorus pesticide. Through enzyme degradation/photocatalytic degradation to common handle chlorpyrifos aqueous solution, keeping40℃and pH of8.5in reaction system what can obtain the highest degradation rate; At the same time, biodegradable initial concentration of chlorpyrifos of20mg/L increase to50mg/L by simple photocatalytic treatment, and20mg/L of chlorpyrifos can be down to within safe limit of0.2mg/L after54h; And concluded that the degradation of chlorpyrifos is P-O bond rupture.