title: Effects of sonication on decolorization of C.I. Reactive Red 198 in UV/ZnO system.
abstract: This study discusses the effects of ultrasound (US) irradiation on the decolorization of C.I. Reactive Red 198 (RR198) in UV/ZnO system. The influences of ZnO dosage, pH and the addition of NaCl or a radical scavenger were evaluated. The decolorization rate of RR198 increased with the ZnO dosage in 0.1-1g/l and with pH in the UV/ZnO system. US accelerated the decolorization of RR198 in the UV-based system. The enhancement in the presence of NaCl can be attributed to an increase in the partitioning of RR198 upon cavitation implosion in US/ZnO system. At pH 7, the decolorization rate constants of UV/US/ZnO, UV/ZnO, US/ZnO, UV/US and US were 0.0739, 0.0534, 0.0022, 0.0020 and 0.0013 min(-1), respectively. The decolorization rate was effectively inhibited by adding 1-butanol to UV/ZnO and UV/US/ZnO systems, suggesting that the main mechanism of RR198 destruction is chemical oxidation by hydroxyl radicals in the bulk liquid. The experimental results revealed that the UV/US/ZnO system cannot only completely decolorize RR198 but can effectively mineralize RR198.
authors.affiliation: Department of Environmental Engineering, Da-Yeh University, 112, Shan-Jiau Road, Da-Tsuen, Chang-Hua, Taiwan, ROC. chunghsinwu@yahoo.com.tw <chunghsinwu@yahoo.com.tw>
authors.forename: Chung-Hsin
authors.initials: CH
authors.lastname: Wu
mesh_terms: D003116:Color; D004396:Coloring Agents / Q000737:chemistry / Q000528:radiation effects; D006863:Hydrogen-Ion Concentration; D009282:Naphthalenesulfonates / Q000737:chemistry / Q000528:radiation effects; D012965:Sodium Chloride / Q000737:chemistry; D013010:Sonication; D014227:Triazines / Q000737:chemistry / Q000528:radiation effects; D014466:Ultraviolet Rays; D014865:Waste Disposal, Fluid / Q000379:methods*; D014874:Water Pollutants, Chemical / Q000737:chemistry / Q000528:radiation effects; D018508:Water Purification / Q000379:methods*; D015034:Zinc Oxide / Q000737:chemistry
chemical_list: D004396:Coloring Agents; D009282:Naphthalenesulfonates; D014227:Triazines; D014874:Water Pollutants, Chemical; D012965:Sodium Chloride; C514337:reactive red 198; D015034:Zinc Oxide