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.

Highlight

•	Satisfactory p-ASA degradation was achieved in a wide pH range.
•	Simultaneous removal of p-ASA and the released arsenic was achieved in biochar supported MnFe2O4/persulfate system.
•	Generation abundant reactive oxygen species via redox cycles between Mn and Fe.

Funding

National Natural Science Foundation of China(51709103)

Natural Science Foundation of Hunan Province, China(2018JJ3242)

Science and Technology Innovation Leading Plan of High Tech Industry in Hunan Province(2021GK4055)

Training Program for Excellent Young Innovators of Changsha(kq1802020)