p-Arsanilic acid decontamination over a wide pH range using biochar-supported manganese ferrite material as an effective persulfate catalyst: Performances and mechanisms

Abstract

Direct chemical oxidation and pure adsorption could not effectively remove p-Arsanilic acid (p-ASA) and the released inorganic arsenic. Herein, one novel biochar supported MnFe₂O₄ (MFB) was synthesized and adopted for p-ASA degradation and synchronous adsorption of the generated inorganic arsenic. The MFB/persulfate (PS) system could remain effective under a wide pH range (3.0–9.0), and the released arsenic could be removed simultaneously by MFB.

Mechanism investigation revealed that the functional groups of MFB (i.e. O–C=O and C=O), Fe and Mn oxides on MFB all contributed to PS activation. O₂^·− and ¹O₂ were the main reactive oxygen species (ROS) responsible for p-ASA degradation, and ¹O₂ was the predominant ROS. Besides, the MFB  possessed superior reusability. Therefore, it is expected to develop a potential method for organic arsenic contaminants removal via an oxidation-adsorption process, and the results could also shed light on the better understanding of the PS activation mechanisms.