title: Adsorption and photocatalytic decolorization of a synthetic dye erythrosine on anatase TiO2 and ZnO surfaces.
abstract: The UV radiation assisted photocatalytic decolorization/degradation kinetics of an anionic dye erythrosine (ER), has been studied over TiO2 and ZnO surfaces. Since adsorption is the prerequisite condition for decolorization/degradation of dye molecules in presence of heterogeneous catalysis, the Langmuir and Freundlich isotherms were examined to verify the adsorption intensity. Standard adsorption free energy measurement implies that the adsorption of ER on both TiO2 and ZnO surfaces is spontaneous endothermic process. The effect of catalyst loading (TiO2/ZnO) revealed the fact that the maximum decolorization rate is obtained under an optimized catalyst loading condition. The decolorization efficiency was also investigated over the pH range of 5.0-10.0 indicating that increasing pH enhances decolorization efficiency. The influence of H2O2 on decolorization efficiency was found noticeable since it is a hydroxyl radical provider. The kinetic study of this degradation indicates that under the experimental condition, the decolorization mechanism follows zero order kinetics on the basis of Langmuir-Hinshelwood (L-H) heterogeneous reaction mechanism.
authors.affiliation: Department of Chemistry, Shahjalal University of Science and Technology, Sylhet-3114, Bangladesh. mahtazim@yahoo.com
authors.forename: M A
authors.initials: MA
authors.lastname: Hasnat
authors.forename: M M
authors.initials: MM
authors.lastname: Uddin
authors.forename: A J F
authors.initials: AJ
authors.lastname: Samed
authors.forename: S S
authors.initials: SS
authors.lastname: Alam
authors.forename: S
authors.initials: S
authors.lastname: Hossain
mesh_terms: D000327:Adsorption; D002384:Catalysis; D003116:Color; D004396:Coloring Agents; D052918:Environmental Restoration and Remediation / Q000379:methods*; D004923:Erythrosine / Q000737:chemistry / Q000528:radiation effects*; D006863:Hydrogen-Ion Concentration; D007700:Kinetics; D010777:Photochemistry / Q000379:methods*; D013499:Surface Properties; D014025:Titanium; D014466:Ultraviolet Rays; D015034:Zinc Oxide
chemical_list: D004396:Coloring Agents; C009495:titanium dioxide; D014025:Titanium; D004923:Erythrosine; D015034:Zinc Oxide