title: Removal of binary azo dyes from water by UV-irradiated degradation in TiO2 suspensions.
abstract: Photodegradation and mineralization of single and binary Acid Orange 7 (AO7) and Reactive Red 2 (RR2) under UV irradiation in TiO(2) suspensions was examined. Experiments were conducted as a function of initial pH, TiO(2) dose, and initial dye concentration. First-order derivative spectrophotometric method was used to simultaneously analyze AO7 and RR2 in binary solutions. The Langmuir-Hinshelwood kinetic model was applied to evaluate and compare the apparent rate constants for the photodegradation of both dyes in single and binary solutions. It was shown that photodegradation of both dyes in binary solution was slower than those in single solution under comparable conditions. Moreover, the difference between the apparent rate constants of RR2 and AO7 became smaller in contrast to the cases of single solutions. After 20-min UV irradiation with 0.5 g/L TiO(2), complete removal of single 0.086 mM AO7 and 0.086 mM RR2 at pH 6.8 was obtained, but only 60% and 45% of binary 0.086 mM AO7 and 0.086 mM RR2 was removed, respectively.
authors.affiliation: Department of Chemical Engineering and Materials Science, Yuan Ze University, Chung-Li 32003, Taiwan. rsjuang@saturn.yzu.edu.tw
authors.forename: Ruey-Shin
authors.initials: RS
authors.lastname: Juang
authors.forename: Su-Hsia
authors.initials: SH
authors.lastname: Lin
authors.forename: Pei-Ying
authors.initials: PY
authors.lastname: Hsueh
mesh_terms: D000327:Adsorption; D001391:Azo Compounds / Q000302:isolation & purification*; D004396:Coloring Agents / Q000302:isolation & purification*; D010777:Photochemistry; D014025:Titanium / Q000737:chemistry*; D014466:Ultraviolet Rays; D014874:Water Pollutants, Chemical / Q000302:isolation & purification*
chemical_list: D001391:Azo Compounds; D004396:Coloring Agents; D014874:Water Pollutants, Chemical; C009495:titanium dioxide; D014025:Titanium