Photoxidation of As3+ to As5+ in the presence of TiO2 under lighting conditions of a lamp and sunlight

Abstract

Efforts to reduce arsenic contamination in water has led to the use of several processes of remediation. Photocatalysis remains one of the techniques yielding better results with lower material and operational costs. In the present study, we obtained the photoxidation of arsenite to arsenate in minutes. We use TiO2 as a photocatalizer with UV and solar lighting. We used an aqueous solution with As III and As V 1 mg/L concentration. The most outstanding results were obtained with 0.1 grams of TiO2 in 150 mL of the solution of As III, reaching a photoxidation to As V of 99% in 4 hours in the reactor with UV lamp. Photoxidation to As V was 94% in 6 hours with a solar lighting prototype using 2 grams of TiO2, in 3 L of a solution of As III. We verified that the As V is adsorbed in the TiO2 powder with or without the presence of light. Regardless of the same conditions, As III was not absorbed. Photoxidation in natural sunlight is somewhat slower compared to the use of a UV lamp, but the energy savings is 100%, providing a significant environmental and sustainability value to the process.