Degradation of Acid Orange II by FeOCl/Biochar-Catalyzed Heterogeneous Fenton Oxidation

In recent years, the rapid development of industry has led to the discharge of large quantities of pollutants, including harmful dyes, into water sources, thereby posing potential threats to human health and the environment. FeOCl and biochar have their own shortcomings as a mediator in the heterogeneous Fenton process. To make both materials useful, FeOCl supported on bamboo biochar (FeOCl/BC) was prepared by calcination using FeCl3·6H2O and bamboo powder as raw materials, and the composite’s catalytic activities were explored with acid orange II (AO-II) as the target pollutant. The degradation efficiency of FeOCl/BC composites on AO-II was determined by testing the mass ratio of FeOCl and BC, initial pH, temperature, H2O2 concentration, catalyst addition, addition of coexisting inorganic anions, and natural organic matter. The addition of biochar to FeOCl increased the activation of H2O2 to generate •OH for the removal of AO-II and accelerated the cycle of Fe3+/Fe2+. The removal rate of AO-II by the Fe1C0.2 composite was 97.1% when the mass ratio of FeOCl and BC was 1:0.2 (Fe1C0.2), which was higher than that of the pure components (FeOCl or BC) at pH = 6.1. Moreover, after five reuses, the Fe1C0.2 composite still showed high degradation activity for AO-II, with 83.3% degradation and low activity loss. The capture experiments on the active material showed that the removal of AO-II by the Fe1C0.2 composite was mainly dominated by •OH; however, •O2− and h+ played minor roles. The synthesized Fe1C0.2 composite could be applied for organic contaminants such as AO-II with high removal efficiency.