Cr(VI) photocatalytic reduction under sunlight followed by Cr(III) extraction from TiO2 surface

• Photocatalytic reduction of Cr(VI) under natural solar light.
• Identification of trivalent chromium species deposed into TiO2 surface.
• Extraction of trivalent chromium from TiO2 surface using citric acid and EDTA.
• Regeneration of TiO2 particles.

The main objective of this work was the extraction of Cr(III) from TiO2 surface deposited after Cr(VI) reduction by TiO2 solar photocatalysis. The results show that the reduction of Cr(VI) to Cr(III) by TiO2 under natural sunlight is total after 2 h using tartaric acid (A.T) as a hole scavenger under the following conditions: [Cr(VI)]: 20 ppm, [TiO2]: 2 g/L, [A.T]: 60 ppm and pH: 2.2. The produced Cr(III) is divided between deposited onto TiO2 surface (39.75%) and in the solution (60.25%). The Cr(III) removal from TiO2 surface by the sequential extraction after three washing were 90.13% and 42.62% using citric acid and EDTA respectively.