Preparation Of Pb( â…¡ )/ZrO_x Catalyst And Its Microwave-assisted Photocatalytic Oxidation Of BPA In Water

Microwave-assisted photocatalysis oxidation process is a new advanced oxidation process for wastewater treatment. Comparing with traditional physical,chemical and biological treatment, it has many advantages such as higher reaction speed and higher oxidation level. In this paper the new-typed Pb(Ⅱ)/ZrOx photocatalyst was prepared, then the microwave-assisted photo-catalysis oxidation of BPA in water based on Pb(Ⅱ)/ZrOx catalyst was set up. The related process conditions and kinetic mechanism were researched, and also studied the components and surface structure of Pb(Ⅱ)/ZrOx catalyst and the role the catalyst played in the reaction.In this paper Pb(Ⅱ)/ZrOx catalyst was prepared via surfactant cetrimonium bromide (CTAB) assisted hydrothermal method and the preparation conditions were optimized: CTAB dosage was 0.4g, the mole ratio of Pb/Zr was 1:100,the mixture reacted under hydrothermal method at 160℃for 12h,pH=10,and the concentration of ZrOCl2 was 0.2mol/L. The structure analysis of the catalyst indicated: The specific surface area of Pb(Ⅱ)/ZrOx catalyst was higher than that of the traditional photocatalyst P25 TiO2,and its average crystal grain size was 13nm. Zr oxides of mix-valences were confirmed to co-exist in Pb(Ⅱ)/ZrOx and the surface of the catalyst was mainly composed by ZrO2 .Pb was loaded on Pb(Ⅱ)/ZrOx successfully as Pb2+.Take bisphenol A(BPA) as the target substance,then microwave-assisted photocatalysis oxidation based on Pb(Ⅱ)/ZrOx catalyst was set up. For 100mL BPA solution with the initial concentration of 50mg/L, the optimum process conditions were: The dosage of Pb(Ⅱ)/ZrOx catalyst was 1g/L,the microwave power for the MW/PC process was 400 W, pH=7,and the light intensity of microwave discharge electrodeless lamp(MDEL) was 9.79 mW/cm2. After reacting under these process conditions, the removel rate of BPA reached 91.9% in 30 min, and the removel rate of TOC reached 85.2%.The apparent kinetics of microwave-assisted photocatalysis oxidation of BPA in water with Pb(Ⅱ)/ZrOx was studied.This reaction accorded with first-order reaction equation: ln([BPA]0/[BPA]) =0.0701t+0.3825, the reaction constant k=0.0701min-1 and the half-life of the reaction t1/2=4.43min. The result of mechanism study showed, with the synergetic effect of microwave and UV, electron of the catalyst was activated and (e--h+) was formed.Then the hydroxyl on catalyst surface or the hydroxyl radical formed from absorbed water made BPA oxidized, decomposing it to CO2 and H2O, which finished the elimination of BPA.