HEAVY METALS AND CYANIDE REMOVAL USING PHOTO-CATALYTIC OXIDATION IN GALVANIZATION WORKSHOPS

Industrial wastewater from galvanization workshops located in meet Ghamer city at Dakahlya governorate in Egypt contains high concentrations of copper, chromium, nickel, zinc and cyanide which violating the Egyptian environmental standard. Three commercial TiO2 specimens were tested in this work namely: TiO2 Degussa P25 (80% anatase, 20% rutile), TiO2 Aldrich (100% anatase) and TiO2 Aldrich (100% rutile) and added with 0.3 ml/l hydrogen peroxide. At optimum operating conditions: TiO2 Degussa P25 photo catalyst (0.25 g l-1), 0.3 ml/l H2O2, PH =11 and temp = 298°C and time photolysis of 30 min., The results confirmed that TiO2 Degussa P25 shows the best photo catalytic activity in the removal of cyanides. The removal efficiency reaches 80%. By increasing time and dose of catalyst give no effect in quality of effluent. So, addition of 1 ml/l hydrogen peroxide to the photo catalytic reaction increases the removal efficiency to 99.8%. Also, 80% of (Cr6+), 70% (Ni2+) and 94.5% (Zn2+) metal ions have been photo catalytically removed from cyanide solution.