Study On Coking Waste-water Treated By Photocatalytic Oxidation Of Nanotitanium

In this Dissertation, a systematic study of degrading the coking waste-water has been done by using photocatalytic technology of nano-titanium oxide based on the review of degradation of printing waste-water, paper making waste-water and various simulative waste-waters using nano- titanium oxide at home and abroad, with corresponding results indicated as follows:1. Through the analyses of GC/MS, the main composition of organic pollution in coking waste-water is phenolic compounds (about 69.30% of these organic pollutions in the coking-water; the total content is 489.8 mg/L), and there are many other organics, such as Tetrahydrofurann, Benzene and homologues, Pyridine, Naphthalene, Quinoline, loquinoline, Indole, Fluorene, Phenanthrene, Anthracene, Carbazole, et al. The results of GC/MS show that using titanium as photocatalyst to degrade coking- water is very effective, and nearly all organic pollution can be eliminated.2. Compared with different catalysts, light sources, photoreactors, the photocatalyst with high activity and reactor with high efficiency have been obtained, and effects of various technical conditions on photocatalytic activity have been studied, then optimizing the best operation parameters.(1) The optimum quantity of titanium powder adding to waste-water is 0.5 g/L;(2) The optimum pH value is 7 for decreasing COD and phenols, but for degradation of NH4+-N the pH value is as higher as possible;(3)Compared with anoxic condition, rich oxygen is much better for increasing catalytic activity, and the optimum flow is 2.5 L/h. The catalytic efficiency has no difference whether if air or oxygen ventilation;(4) There are no difference with adding Hydrogen peroxide and ventilating oxygen to waste-water. The optimum quantity of Hydrogen peroxide adding to reactor is 3 mL/L;(5) The optimum calcinated temperature is 700 C for titanium powder;(6) The most suitable reaction time is 10 hours, and more reaction time is no necessary;(7) The results show that the effectiveness of factors on COD decreased in order of pH value, reaction time and the quantity of titanium powder , but on NH4+-N and phenols in order of pH value, quantity of titanium powder and reaction time.3. 83.33% of COD and 98.24% of phenol can be decreased under the optimum condition.4. In order to improve the photocatalytic activities of titanium, nano-SnO2 can be used to wrap TiO2, and only when the TiO2 wrapped by more than 5% SnO2, the enhancement of photocatalytic activities is remarkable.