Journal of North Khorasan

Abstract Backgrounds & Objectives: Since of heavy metal such as chromium in the environment has a major risk, including skin cancer and lung and kidney and liver damage. Aim of present study was investigation removal of Cr (VI) using photo-chemical and photo-catalytical process such as UV/ZnO, UV/TiO2 and UV/H2O2 from aqueous solution. Material & Methods: In this study, factors affecting recovery processes such as catalyst concentration (0.05-0.15 g / L), the concentration of H2O2 (0.5-1.5 mol / L) and pH were investigated, initial substrate concentrations between 0.1 to 15 mg/L was varied. Stock solution of chromium (VI) was prepared using the solubility of potassium dichromate (K2Cr2O7) in distilled water. Residual concentration of chromium was measured by spectrophotometer at wavelength 540 nm. Results: The results showed that with increasing TiO2, ZnO nanoparticles , H2O2 concentration and decreasing pH increased the efficiency of Cr removal. Also removal efficiency decreased with increasing initial concentration of Cr (VI). Maximum reduction of Cr(VI) with ZnO was Occurred in 4 to 8 pH range. With increasing pH, the removal efficiency for TiO2 and H2O2 decreased. The results showed that reduction of Cr(VI) follows approximately Langmuir–Hinshelwood first-order kinetics model. Conclusion: The obtained results indicate that can be used UV/ZnO, UV/H2O2 and UV/TiO2 to remove Cr(VI) from aqueous solutions, as a friendly environmental treatment processes and without residual