Preparation And Properties Of Nano-catalysts For Heterogeneous Catalytic Ozonation

Heterogeneous catalytic ozonation is a hot spot in the research of environmental treatment technology at present for degradation organic pollutants in water.In the thesis,The new and efficient nano-catalysts?fibrous nano-silica CuO/KCC,fibrous monodisperse core-shell nanostructured Cu-Mn/Fe₃O₄@Si O₂@KCC and yolk-shell nanostructured Fe₃O₄@NiSiO₃?were prepared and characterized.Then used in heterogeneous catalytic ozonation system for the treatment of refractory organic wastewater.Catalytic performance of the catalyst and the effect of reaction conditions on oxidative removal of terephthalic acid?PTA?were investigated.The kinetics and mechanisms for degradation of PTA were further studied.At the same time,the catalytic ozone oxidative degradation effect of four different structures dye wastewater?orange G,disperse blue 56,malachite green and methylene blue?was studied by the catalytic ozonation.The main experimental conclusions were as follows:1)The main preparation of CuO/KCC was by microemulsion method and impregnation method.Under the conditions of ozone rate of 7.41 mg·min^-1,initial solution pH value of 9,catalyst dosing quantity of 75 mg·L^-1,temperature of 20?and reacting time of 20 min,the removal efficiency of PTA and TOC was up to 60.85%and 11.83%.Comparing with ozonation alone process,the removal efficiency and TOC were enhanced by 12.62%and 6%,respectively.The degradation of PTA fitted the pseudo-first-order reaction kinetics.The catalyst also shows good catalytic stability after 5 cycles.The free radical trap experiment proved that the catalytic ozonation followed a hydroxyl radical mechanism.2)The main preparation of Cu-Mn/Fe₃O₄@SiO₂@KCC was by microemulsion method and impregnation method.Under the conditions of ozone rate of 13.92 mg·min^-1,initial solution pH value of 9,catalyst dosing quantity of 40 mg·L^-1 and reacting time of 20min,the removal efficiency of PTA and TOC was up to 90.97%and 26.78%.Comparing with ozonation alone process,the removal efficiency and TOC was improved by 8.72%and 8.08%,respectively.The degradation of PTA fitted the pseudo-first-order reaction kinetics.The catalyst also shows excellent catalytic stability after 5 cycles.The free radical trap experiment proved that the catalytic ozonation followed a hydroxyl radical mechanism.The degradation rate of simulated dye wastewater was 81.80%,68.97%,88.44%and 98.92%,respectively.3)The Fe₃O₄@NiSiO₃ magnetic nanoparticles were prepared by hydrothermal synthesis and sol-gel method.Under the conditions of ozone rate of 13.92 mg·min^-1,initial solution pH value of 9,catalyst dosing quantity of 40 mg·L^-1 and reacting time of 20 min,the removal efficiency of PTA and TOC was up to 78.13%and 27.25%.Comparing with ozonation alone process,the removal efficiency and TOC was enhanced by 19.16%and9.48%,respectively.The degradation of PTA fitted the pseudo-first-order reaction kinetics.The catalyst also shows appropriate catalytic stability after 5 cycles.The free radical trap experiment proved that the catalytic ozonation followed a hydroxyl radical mechanism.The degradation rate of simulated dye wastewater was 98.58%,75.86%,93.06%and99.06%,respectively.