USE OF PHOTOCATALYSIS FOR THE REMOVAL OF Fe AND Cu

Background: The advancement of the mining industry implies the generation of acid drainage because operations consume between 2% and 4.5% of water demand. In addition, it is estimated that 50,000 tons of waste will be produced, of which 33% represents wastewater stored in tailings tanks. These effluents contain heavy metals such as Fe and Cu that represent a serious danger to society. Aim: The objective of this study is to evaluate the application of photocatalysis for the removal of Fe and Cu in industrial wastewater. This involves the control of process parameters: the catalyst dose (TiO2), pH, and time (days). Methods: The method used is experimental, controlling the process variables through a factorial design. The process variables were monitored applying the 33 factorial design, that is, 3 factors with 3 levels without repetitions. The tests were conducted under conditions with a catalyst at doses of 1.2 and 3 g/L, pH of 2.5 and 8, and a retention time of 1, 2, and 3 days. Therefore, the combination of the factors resulted in 27 experimental units. Results and Discussion: For the photocatalysis application time, in 2 days there were fewer concentrations of Fe and Cu, reaching 0.02 and 0.09 ppm, respectively. In the case of pH, a value of 8 resulted in lower concentrations of Fe and Cu. The optimal dose of the catalyst was 0.5 g/L of TiO2. The removal efficiency was 99.99% for Fe and 99.97% for Cu. In the factor analysis, it is observed that pH has the greatest influence on the removal of Fe and Cu, followed by the time factor. A strong interaction between the two variables is also observed. Conclusions: In conclusion, it was possible to remove Fe and Cu through the application of photocatalysis in synthetic wastewater. The optimal conditions were: pH 8, application time of 2 days, catalyst dose (TiO2) 0.5 g/L, and a removal efficiency greater than 99.90%. These values were similar to those reported by other authors.