Enhancement of p,p'-DDT photodegradation on soil surfaces using TiO2 induced by UV-light

• Published in: Chemosphere (Oxford) Vol. 60; no. 2; pp. 266 - 273
• Main Authors: Quan, X, Zhao, X, Chen, S, Zhao, H, Chen, J, Zhao, Y
• Format: Journal Article
• Language: English
• Published: Oxford Elsevier 01.07.2005
• Subjects: agricultural soils; Applied sciences; Biodegradation, Environmental; DDT (pesticide); DDT - metabolism; DDT - radiation effects; Decontamination. Miscellaneous; Earth sciences; Earth, ocean, space; Engineering and environment geology. Geothermics; Exact sciences and technology; Half-Life; humic substances; Humic Substances - toxicity; Hydrogen-Ion Concentration; insecticide residues; light intensity; Oxidation-Reduction; Photochemistry; photolysis; Photons; Pollution; Pollution, environment geology; Soil - analysis; Soil and sediments pollution; soil pH; Time Factors; Titanium - chemistry; titanium dioxide; ultraviolet radiation; Ultraviolet Rays; Water Pollutants, Chemical - metabolism; Water Pollutants, Chemical - radiation effects; Reaction intermediate; Organic matter; Insecticide; Environmental factor; Soil surfaces; Soil pollution; Humic substances; Decontamination; DDT; Organochlorine compounds; p,p'-DDT; Chlorine Organic compounds; Reaction mechanism; Oxidation; Photochemical degradation; Photodegradation; UV-light; Photocatalysis; Pesticides; Property of soil; Endocrine disruptor; Heterogeneous catalysis; Ultraviolet radiation; Kinetics; Titanium oxide; Photooxidation; Degradation product; TiO2
• ISSN: 0045-6535; 1879-1298
• DOI: 10.1016/j.chemosphere.2004.11.044

Enhancement of p,p'-DDT photodegradation on soil surfaces using TiO2 induced by UV-light was mainly investigated in this work. After being spiked with p,p'-DDT, soil samples loaded with different doses of TiO2 (0%, 0.5%, 1%, 2%, and 3% wt) were exposed to UV-light irradiation for 24 h. The results indicated that the photodegradation of p,p'-DDT followed the pseudo-first-order kinetics. TiO2 accelerated the photodegradation of p,p'-DDT significantly as indicated by the half-life reduction from 23.3 h to 10.4 h, corresponding to the TiO2 content from 0% to 3% respectively. In addition, the effects of soil pH, photon flux and humic substances on p,p'-DDT degradation were investigated. The photodegradation rate increased with the increase of the soil pH and photon flux. The humic substances (2% wt) inhibited the p,p'-DDT photodegradation by reducing the amount of light available to excite the p,p'-DDT and TiO2 or by quenching radicals capable of oxidizing p,p'-DDT. p,p'-DDE, p,p'-DDD and DDMU were main degradation intermediates and they were further degraded in the presence of TiO2.