The Degradation Of Dye Wastewater By Photocatalytic Oxidation And Reduction

Dyeing and printing industry is a large source of industrial wastewater discharge.due to the hole- semiconductor electron pair recombination rate is high, and the light utilization rate is low, TiO2 semiconductor photocatalyst catalytic degradation of pollutants is difficult to widely used in the industry the photocatalytic oxidation treatment of printing and dyeing wastewater.As a main approach to degradation of organic pollutants, although the treatment effect is good, the preparation of nano pHotocatalyst technology is complex and high cost; Due to the poor treatment effect and the reducing environment is not easy to control, the research in the field of pHotocatalytic reduction is restricted, so it is concentrated on the conversion of CO2 and removing of metals;SO2 is a typical air pollutant, its by-products Na2SO3,can not be used efficiently because of its low purity.This topic mainly aimed at the field of photocatalytic oxidation and light catalytic reduction, it include that pHotocatalytic oxidation degradation of acid orange(AOII) by simple cerium and pHotocatalytic reduction of methyl orange(MO) by sodium sulfite.Using the Ce3 + and Ce4 + build different pHotocatalytic oxidation system, discussing different pHotocatalytic oxidation system of AOII, effect on the degradation of nitro pHenol(PNP), comparing the influence of different PH light catalytic oxidation system, and analyze the mechanism of oxidation; Using sodium sulfite,a waste products of SO2,build a pHotocatalytic reduction system,and using it to explore the different concentrations of catalyst, the effects of the different concentrations of MO on the degradation, determin the best process conditions and the degradation rate of rhodamin B, alizarin(AG), the nitro pHenol(PNP) and methylene blue; Exploring the effects of PH, N2 and O2 environment to the degradation of MO and researching the pHotocatalytic reduction mechanism of MO and product analyzed. The results show that:(1) In the original pH and reaction 40 mime, the degradation rate of AOII was 81% by Ce4 + / UV system, but it was 62% by Ce3 + / UV system.Beside, Ce4 + / UV system reflect a better degradation effect in PNP than the Ce3 + / UV system.(2) Under the original pH value(pH = 3.5)of Ce4 + cerious, reaction within 40 mime, Ce4 + / UV system reflects a faster reaction rate than Ce3 + / UV system in degradation AOII, but in the end, the degradation effect reach the same(81%); Under the alkaline condition, Ce4 + / UV system no catalytic effect, while the Ce3 + / UV system has a good catalytic effect.(3) It was certified that the main effect of AOII degradation is OH ? in this two systems, and the Ce3 + and Ce4 + may transform into each other and generate OH ? under pHotocatalysis,and Ce4 + to Ce3 + conversion process is dominating.(4)The optimum process conditions of pHotocatalytic reduction system in degradation of MO: MO 40 mg/L, Na2SO3 4 mm; The way of determin optimum degradation process of rhodamin B, alizarin rate(AG), nitro pHenol(PNP), methylene blue is the same.(5) the results show that the PH was little impact on pHotocatalytic degradation of MO; Trace metal elements no promoting effect on the degradation of MO; Comparing Na2SO3 photocatalytic degradation of MO between N2 environment and find that it has better effect on O2 environment.(6)It was proved that the photocatalytic reduction system of Na2SO3 produced active species, through the analysis of degradation products of MO, finding that MO has restored into the intermediate and further into small molecule compounds.