title: Photocatalytic degradation of p,p'-DDT under UV and visible light using interstitial N-doped TiO₂.
abstract: 1,1,1-trichloro-2,2-bis(p-chlorophenyl)ethane (or p,p'-DDT) is one of the most persistent pesticides. It is resistant to breakdown in nature and cause the water contamination problem. In this work, a major objective was to demonstrate the application of N-doped TiO2 in degradation and mineralization of the p,p'-DDT under UV and visible light in aqueous solution. The N-doped TiO2 nanopowders were prepared by a simple modified sol-gel procedure using diethanolamine (DEA) as a nitrogen source. The catalyst characteristics were investigated using XRD, SEM, TEM, and XPS. The adsorption and photocatalytic oxidation of p,p'-DDT using the synthesized N-doped TiO2 under UV and visible light were conducted in a batch photocatalytic experiment. The kinetics and p,p'-DDT degradation performance of the N-doped TiO2 were evaluated. Results show that the N-doped TiO2 can degrade p,p'-DDT effectively under both UV and visible lights. The rate constant of the p,p'-DDT degradation under UV light was only 0.0121 min(-1), whereas the rate constant of the p,p'-DDT degradation under visible light was 0.1282 min(-1). Under visible light, the 100% degradation of p,p'-DDT were obtained from N-doped TiO2 catalyst. The reaction rate of p,p'-DDT degradation using N-doped TiO2 under visible light was sixfold higher than that under UV light. According to Langmuir-Hinshelwood model, the adsorption equilibrium constant (K) for the N-doped TiO2 under visible light was 0.03078 L mg(-1), and the apparent reaction rate constant (k) was 1.3941 mg L(-1)-min. Major intermediates detected during the p,p'-DDT degradation were p,p'-DDE, o,p'-DDE, p,p'-DDD and p,p'-DDD. Results from this work can be applied further for the breakdown of p,p'-DDT molecule in the real contaminated water using this technology.
authors.affiliation: a Department of Environmental Engineering , King Mongkut's University of Technology Thonburi , Bangkok , Thailand.
authors.forename: Jirapat
authors.initials: J
authors.lastname: Ananpattarachai
authors.forename: Puangrat
authors.initials: P
authors.lastname: Kajitvichyanukul
mesh_terms: D003634:DDT / Q000737:chemistry*; D007306:Insecticides / Q000737:chemistry*; D008027:Light; D009584:Nitrogen / Q000737:chemistry; D010782:Photolysis; D014025:Titanium / Q000737:chemistry*; D014466:Ultraviolet Rays; D014874:Water Pollutants, Chemical / Q000737:chemistry*
chemical_list: D007306:Insecticides; D014874:Water Pollutants, Chemical; C009495:titanium dioxide; D003634:DDT; D014025:Titanium; D009584:Nitrogen
keywords: DDT; N-doped TiO2; degradation; oxidation; photocatalyst; visible light