STUDY ON PHOTOCATALYTIC PERFORMANCE OF TiO2 FILM PREPARED ON Q235A STEEL AND ITS DEGRADATION OF ORGANIC POLLUTANT IN SIMULATED WASTEWATER

TiO2 film is prepared on the surface of Q235A substrate from an acid solution (pH=2) to research its degradation of methylene blue organic pollutant in wastewater. The titanium oxysulfate is used as the titanium precursor to provide the source of titanium. The preparation of TiO2 film is mainly a polymerization reaction of titanium oxysulfate, which makes Ti2O52+ and OH− combine to produce [Ti2O5(OH)2]n precipitation deposited on the cathode surface by electrochemical reaction. TiO2 film is formed after high temperature heating. The nitrate ion which derives from potassium nitrate in the electrolyte is reduced to hydroxide ion during the electrochemical reaction process, resulting in the formation of titanium compounds and titanium hydroxide. The TiO2 film prepared from solution containing 0.2 mol/L KNO3 has the best photocatalytic performance which can effectively degrade the methylene blue organic pollutant in wastewater. However, when the KNO3 in the solution is 0.25 mol/L, excessive hydroxide ions inhibit the hydrolysis of titanium salts and accelerate the oxygen evolution resulting in the decrease of degradation efficiency.