Study On Catalytic Ozonation Of Rubber Wastewater With Copper Cerium Lanthanum Composite Metal Oxide

In recent years, with the growing of chemical industry wastewater pollution, chemical wastewater treatment has became an important environmental issues in China. At present, most of the sewage treatment plant took the traditional water treatment technology on chemical wastewater treatment. But with the characteristic of large chemical waste water, many kinds of compounds, more organic, biodegradable, it is difficult to deal with emissions standards. Therefore more efficient water treatment technology has to be applied to deal with such wastewater.With its strong oxidation resistance and good stability, Catalytic ozonation technology as one of the efficient advanced oxidation technology has a good prospects in the depth of chemical wastewater treatment. In this paper, copper lanthanum cerium mixed metal oxide catalysts were prepared for treating the secondary biochemical effluent of rubber wastewater with catalytic ozonation technology.The treatment conditions and the preparation conditionswere investigated under the experiment. The main results are as follows:(1) With over ?-Al2O3 coated cordierite honeycomb ceramic (Cordierite honeycomb, CH) as the carrier were prepared by copper lanthanum cerium mixed metal oxide catalyst (Cu-Ce-La-O/CH) impregnation method for catalyst preparation process optimized. The results showed that when the active component ratio of n(Cu):n(Ce):n(La)=4:2:1 and calcined at 550?, the catalytic activity of the catalyst is best.(2) By the intermittent operation, the effect of ozonation and adsorption capacity of copper cerium lanthanum metal composite oxide catalysts for catalytic ozonation were respctively observed, and the optimum technological conditions for the catalytic ozonation of rubber wastewater by copper cerium lanthanum composite metal oxide catalysts was studied. The results show that the influnce of the adsorption of the catalyst and the ozonation on the CODcr to catalytic ozonation was very small. By the conditions the ozone concentration of 4.588mg·L-1, gas flow of 0.3L·min-1, reaction temperature of 20?, the catalyst dosage of 56.3g and the hudraulic detention time of 60minutes, catalytic ozonation of initial CODCr for 200mg·L-1 rubber wastewater of two grade biochemical effluent highest CODcr removal rate reached 60.4% and CODCr of the effluent was less than 80mg·L-1.The CODCr of the effluent accorded with the discharging standard of China.(3) By continuous operation, the stability of the catalytic ozonation of the catalyst and dissolution of Cu2+ was studied. The results showed that catalyst maintained a high catalytic activity and the catalytic efficiency remained stable after 84h with the optimum technological conditions for the catalytic ozonation by the intermittent operation. The CODd removal rate of the catalyst for the two garde biochemical effluent of rubber wastewater was kept at 55%-57%, and the concentration of Cu2+ in effluent water which was under 0.5mg·L-1 accorded with the discharging standard of China.(4) By adding hydroxyl free radical inhibitor tertiary butanoe, the reaction mechanism was studied. The results showed that ozone oxidation and the catalytic ozonation process followed the hydroxyl radical reaction mechanism, and the reaction process was in accordance with the first order kinetic reaction. The reaction rate constant of catalytic ozonation alone is much larger than ozone oxidation.