Abstract:
Photocatalysis is a novel technology in water/wastewater treatment process. By illumination thesemiconductor with ultraviolet light, electron-hole pairs are formed. These charge carriers arecapable of reducing or oxidizing pollutant species in solution. In general photocatalysis consists of2 steps: the adsorption process and irradiation process. The later part is the major subject of this study.In this study Chromium(VI) or Cr(VI) removal from synthetic wastewater by UV-irradiatedtitanium dioxide is extensively investigated. Role of pH, TiO2 dosage, organic and inorganicadditives on photocatalysis of Cr(VI) are examined and discussed. It is found that the optimum pHfor Cr(VI) removal after prolonged UV-irradiation is at pH 3 with 59.40 percents Cr(VI) removalefficiency. The photoreduction rate was pseudo-first-order with respect to the initial concentrationwithin the experimental range. In the presence of formate ions, The Cr(VI) removal efficiency isenhanced to 82.46 percents. On contrary, chloride, sulfate and phosphate ions prohibited thephotocatalytic reduction process. Tentative schemes of reaction mechanism for these effect are alsogiven.