Photocatalytic reduction of phosphorus in the acid pickling milling wastewater from high-phosphorus hematite mineral processing

The photocatalytic reduction of phosphorus in the acid pickling milling wastewater from high- phosphorus hematite mineral processing was innovatively performed in the absence of oxygen and in the presence of hole scavenger under visible light irradiation with Sr-doped TiO2 in the study. Types and ratio of hole scavenger, effect of reduction time, dosage of Sr-doped TiO2 and initial phosphorus concentration on the reduction of phosphorus were investigated. Experimental results indicated that the gaseous product of the photocatalytic reduction was identified to be phosphine. The optimum amount of formic acid and TiO2 were 60 mmol l-1 and 2.0 g l-1, respectively, and the phosphorus removal could reach 99.96% when used to treat the actual mineral processing wastewater. The photocatalytic reduction of phosphorus could be described by first order kinetic equation, and the reaction rate was proportional to the concentration of reactants.