Synthesis of novel polyoxometalate K6ZrW11O39Sn•12H2O and photocatalytic degradation aqueous azo dye solutions with solar irradiation

A new environment-frienldly material, K6ZrW11O39Sn center dot 12H(2)O (ZrW11Sn), was synthesized by hydrothermal coprecipitation and characterized. The photocatalytic activities of ZrW11Sn were evaluated by its photocatalytic degradation of Acid Brilliant Scarlet 3R (ABS3R), Reactive Red 24 (RR24), and Reactive Black 5 (RB5) with natural sunlight in homogeneous aqueous solutions. Results indicated that ZrW11Sn effectively and photocatalytically decolorized ABS3R, RR24, and RB5. The photocatalytic degradation of ABS3R was influenced by catalytic dosage, photolysis time, initial pH, and concentration. ZrW11Sn-mediated photocatalytic degradation of ABS3R was a pseudo first-order reaction and modeled by Langmuir-Hinshelwood-type kinetics. The effects of HO center dot(Br-) and photogenerated hole scavengers (I-) on the degradation rate of ABS3R were evaluated. Kinetic probes of the degradation mechanism indicated that hydroxyl radicals and photogenerated holes were the main oxidants in the reaction and that the oxidation of holes was predominant. ABS3R solution (20 mL, 6 mg/L; initial pH 6) with ZrW11Sn (1 g/L) was irradiated for 4 h under sunlight, the decoloration rate of which was over 69%. The azo structure of ABS3R molecules was destroyed, and NH4+, NO3-, and SO42- were detected in the irradiated solution. (C) 2014 Elsevier B.V. All rights reserved.