Light-assisted decomposition of dyes over iron-bearing soil clays in the presence of H2O2.
Four types of soil clays from different sites in China have been chosen to simulate chemical remediation of soils contaminated with dyes by light-assisted Fenton-like method. X-Ray diffraction (XRD), X-ray photoelectron spectroscopic (XPS) and electron spin resonance (ESR) measurements indicated that these soil clays contain iron oxides such as magnetite and hematite, where nondistorted iron active sites (ESR spectra, g=2.3) predominate. Upon visible or UV irradiation, the soil clays were very effective for the degradation of nonbiodegradable cationic dyes such as Rhodamine B (RhB) by activating H(2)O(2) at neutral pH. The photodegradation rates of RhB were closely related to total Fe content in clays and H(2)O(2) dosage, indicating the mineral-catalyzed Fenton-like reactions operated. Soil organic matters (SOM) would remarkably inhibit the photodecomposition of RhB dye. The reaction products were some low-molecular-weight dicarboxylic acids and their derivatives, all of which are easily biodegradable. A possible mechanism was proposed based on the results obtained by spin-trapping ESR technique.
Beijing National Laboratory for Molecular Sciences, Key Laboratory of Photochemistry, Institute of Chemistry, The Chinese Academy of Sciences, Beijing 100190, China.
Zhaohui
Z
Wang
Wanhong
W
Ma
Chuncheng
C
Chen
Jincai
J
Zhao
D000538:Aluminum Silicates; D000077215:Clay; D004396:Coloring Agents / Q000737:chemistry*; D004578:Electron Spin Resonance Spectroscopy; D006861:Hydrogen Peroxide / Q000737:chemistry*; D007501:Iron / Q000737:chemistry*; D007700:Kinetics; D008027:Light; D012987:Soil; D013057:Spectrum Analysis / Q000379:methods; D014466:Ultraviolet Rays; D014965:X-Rays
D000538:Aluminum Silicates; D004396:Coloring Agents; D012987:Soil; D006861:Hydrogen Peroxide; D007501:Iron; D000077215:Clay