A Dissertation Presented To The Academic Degree Committee Of Nanjing University For Applying The Masterate

Due to the high catalytic efficiency, stable and controllable structure, biomimetic catalyst is attracting increasing attentions in the field of environmental remediation. As one of the advanced oxidation methods, biomimetic catalyst simulating the function of peroxidase has great potential for degradation of many organic contaminants.In this thesis, natural montmorillonite (MMT) was initially exchanged with copper ion to obtain Cu2+saturated MMT (Cu-MMT). Hemin, as the active center of horseradish peroxidase (HRP), was immobilized into Cu-MMT interlayer through co-solvent effect and complexation between Cu2+and carboxyl group of hemin. It was demonstrated that with the increase of the fraction of water in co-solvent system, the adsorption of hemin onto MMT also increaed. The results from X-ray diffraction, Fourier transform infrared spectroscopy and theoretical calculations all confirmed the strong interaction formed between Cu2+and hemin, which significantly increased the amount of hemin adsorbed onto MMT. In addition, UV-vis spectrum showed that hemin immobilized on Cu-MMT was present in highly active monomer state.The2,4,6-trichlorophenol (TCP) degradation results showed that the reactivity of hemin-Cu-MMT bioconjugate increased linearly with the increase of the amount of hemin immobilized. Hemin-Cu-MMT system had higher reactivity at low pH and remained active at temperature as high as70℃. Also, no selectivity towards TCP was observed in this system. Hemin-Cu-MMT lost～90%of its reactivity after4catalytic cycles, which might be explained by the destruction of hemin with H2O2or by the blockage of the active sites in hemin by the polymerization products of TCP.