Simultaneous Removal of Methylene Blue and Hexavalent Chromium From Water Using TiO 2 /Fe(III)/H 2 O 2 /Sunlight

The objective of the present work was the simultaneous removal of methylene blue (MB) and hexavalent chromium from water using the combined system TiO 2 /Fe(III)/solar. The comparison between the three processes, i.e ., iron cycle (Fe(III)/solar), photocatalytic reactions (TiO 2 /solar), and the combined system (TiO 2 /Fe(III)/solar) for single and simultaneous removal cases was investigated. The results show that only the TiO 2 /Fe(III)/solar system ensures a complete simultaneous removal. A total simultaneous removal of Cr(VI) and MB at a concentration of 30 ppm for each substrate was achieved under natural sunlight within 5 h by the use of 0.16 g/L of TiO 2 and 40 ppm of Fe(III). The effects of concentration ratio of substances, solution pH and the presence of H 2 O 2 in the combined system were investigated. Finally, based on the obtained results, a removal pathway of both pollutants by TiO 2 /Fe(III)/H 2 O 2 /solar system was proposed. This fast synergistic combined system is a significant option for both oxidation and reduction reactions.