Self-assembled Fe3+@spores as a sustainable heterogeneous Fenton catalyst for arsenite removal

Abstract

The removal of arsenic from natural water has recently attracted the attention of the scientific community and health care departments. We developed a novel heterogeneous Fenton catalyst based on Fe3+-loaded Bacillus. subtilis spores (i.e., Fe3+@spores microspheres) providing a dual functional role for As(III) oxidation and subsequently for As(V) adsorption. The heterogeneous Fenton catalyst exhibited excellent removal efficiency for As(III), reaching approximately 97.50 % of As(III) removed in 90 min. The mechanism of As(V) adsorption was characterized by using Fourier transform infrared (FTIR) spectra and X-ray photoelectron spectroscopy (XPS), demonstrating that the form of Fe-O-As plays a key role in As(V) adsorption. The heterogeneous Fenton catalyst exhibited excellent ion tolerance in the presence of interferential ions (e. g., HCO3−, HPO4−, CO32−, NO3−, and Cl−) and adaption to different water environments (e. g., deionized water, tap water, and lake water). Moreover, the spores recovered by centrifugation could be reused at least 10 times. Thus, the developed catalyst exhibited potent advantages, such as eco-friendliness, low cost, ease of accessibility and storage, and recyclability. These characteristics suggested that the proposed catalyst has great potential application for arsenic removal in the treatment of contaminated waters.