Determination of the parameters for photocatalytic degradation from Chromium hexavalent to Chromium trivalent in a solar parabolic cylindrical concentrator in a simulated sample from tanning

The purpose of this study is to determine the efficiency of photocatalytic​ reduction (UV/TiO₂) from Hexavalent Chrome to Trivalent Chrome using a solar parabolic cylindrical concentrator for a simulated effluent sample from the tanning processes. For this purpose, a model of the solar parabolic cylindrical reactor was used, which was considered the most suitable for the capture of radiation and for its mobilization. The independent variables of the simulated liquid effluent sample were pH, temperature (T), flow (Q), hexavalent chrome concentration and dependent variables were the efficiency of the results, solar radiation and titanium dioxide concentration [TiO₂]. The optimum processing values were: pH= 3.75; Q= 8.2; T= 30; [TiO₂]= 30g. The results of the simulated samples were decreasing from 0.183 mg/L to the values of the maximum permissible limits (MPL) of 0.4 mg/l. In the results carried out before the photocatalytic treatment of the actual tannery sample from the Rio Seco Industrial Park, 326.95 mg/L was obtained, the concentration of hexavalent chromium was 173.28 mg/L. After the photocatalytic treatment, 58.85 mg/L and 25.89 mg/L were obtained respectively, with a reduction of the efficiency from 3 to 1. It is feasible to perform the photocatalytic​ treatment using the Parabolic Cylinder Reactor on a semi-industrial scale for the reduction of Cr⁺⁶ to Cr⁺³. The research solves the current problems of the tanning companies in Arequipa. The optimal operation conditions are an exposure time of 4 h, between 10 am and 2.00 pm, with a radiation intensity of 875 W/m².