Photocatalytic degradation of rhodamine B by Bi(2)WO(6) with electron accepting agent under microwave irradiation: mechanism and pathway

J Hazard Mater. 2009 Mar 15;162(2-3):1477-86. doi: 10.1016/j.jhazmat.2008.06.047. Epub 2008 Jun 21.

Abstract

Bi(2)WO(6) was successfully synthesized by a facile hydrothermal method, and characterized by transmission electron microscopy (TEM), X-ray diffraction (XRD) and BET. As a result, Bi(2)WO(6) crystals displayed mainly square-plate-like morphologies with a short edge and the average crystalline size was in the range of 50-150 nm. Then microwave-assisted photocatalytic degradation of rhodamine B (RhB) using Bi(2)WO(6) was investigated. The results illustrated that RhB (10 mg/L) was bleached effectively and the removal efficiency was about 94% in 60 min. Effect of electron accepting agent (air, H(2)O(2)) on the degradation efficiency of RhB was also examined. Degradation intermediates of RhB in the presence of H(2)O(2) were identified by LC/MS/MS and GC/MS. All five N-de-ethylated intermediates were monitored by LC/MS/MS easily, and seven organic acids such as succinic acid, benzoic acid, adipic acid, 3-hydroxybenzoic acid, phthalic acid, etc., were also detected by GC/MS. The possible degradation mechanism of RhB in the presence of H(2)O(2) included four processes: N-de-ethylation, chromophore cleavage, opening-ring and mineralization, which coexisted in microwave-assisted photocatalytic system.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Bismuth / chemistry*
  • Catalysis
  • Microscopy, Electron, Transmission
  • Microwaves*
  • Photochemistry
  • Rhodamines / chemistry*
  • Spectrophotometry, Ultraviolet
  • Tungsten / chemistry*
  • X-Ray Diffraction

Substances

  • Rhodamines
  • rhodamine B
  • Bismuth
  • Tungsten