Sunlight Irradiated Pyrite-Fenton System for Advanced Oxidative Treatment of Textile Dyes Mixture

In this work, the advanced oxidation technology was investigated through the degradation of a solution composed of four textile dyes, more complex than the solutions used in similar researches. For this purpose, heterogeneous photo-Fenton process was applied, using the mineral pyrite as iron catalyst and sunlight as a radiation source. This research aimed to identify and determine the most appropriate experimental conditions to conduct the treatment, revealing the influence of the variables pH and iron and H 2 O 2 concentrations on degradation efficiency. The highest degradation (99.74%) and organic matter conversion (95.03%) were observed at pH 3, using 100 mg·L −1 of H 2 O 2 and 0.5 g·L −1 of pyrite for 60 min. Under these conditions, non-linear pseudo-first order and linear pseudo-first order and pseudo-second order kinetic models described the reaction kinetics the treatment (accuracy > 91%). The toxicity analysis revealed a possible formation of toxic intermediates, as the natural development of seed species and the mollusc Biomphalaria glabrata was affected. In general, the adequacy of the proposed treatment and the good use of pyrite in Fenton’s heterogeneous systems were evidenced.