Abstract

A new technology for arsenic (As) removal have been addressed by mean of the design and construction of a treatment prototype equipment. This prototype is mainly composed of a solar collector as a photo-reactor and the use of a bi-functional material based on a specific semiconductor (TiO2) and an activated carbon (AC). Preliminary results about the influence of the radiation wavelength (UV and/or Visible) and the radiation flux (W/m2) on the photo-oxidation of As (III) was obtained in a laboratory scale. For this, it was considered a small-scale photo-reactor with different configurations of UV-Vis lamps, 200ml of As (III) solution and a selected load of material suspended in the contaminant solution. It was observed that the incorporation of visible lamps increases the radiation flux in about 40W/m2, however, the photo-oxidation time increases up 90 minutes, demonstrating that the photo-efficiency of the system is more influenced by the wavelength of the light instead of the radiation power. Then, the prototype was built as a photo-reactor type coupled to a composite parabolic collector (CPC), and a simulated solar illumination system. The efficiency to remove As was evaluated for a synthetic solution of As (III) (1000 and 5000 ppb, pH 4). In presence of TiO2-AC a higher adsorption capacity of As (V) and lower time for disappearance of As (III) were observed, with respect to using TiO2 alone, demonstrating a synergistic effect between both solids. In summary, it was determined that the system TiO2-AC presented a high removal efficiency (> 90%), which involves the photo-oxidation of As (III) between 30-60 min and the progressive adsorption of As (V), reaching irrigation water quality standards.