Efficient removal of bisphenol A by a novel biochar-based Fe/C granule via persulfate activation: Performance, mechanism, and toxicity assessment

Abstract

Fe–C microelectrolysis is an efficient wastewater treatment technology for biorefractory pollutants. However, the poor stability and complicated separation mechanism of microelectrolytic materials hinder their application in advanced oxidation processes. Thus, herein, catalytic Fe–C microelectrolysis granules (FeBCGs) were prepared using Fe powder and sawdust and were used as persulfate (PS) activators for bisphenol A (BPA) removal. The effects of the calcination temperature, Fe/sawdust mass ratio, FeBCG concentration, PS concentration, initial pH, and initial BPA concentration were investigated. Under optimal conditions ([FeBCG]0 = 0.5 g/L, [PS]0 = 1 mM, without pH adjustment), the BPA removal efficiency reached 100% within 20 min. The FeBCGs presented numerous functional groups and a porous structure, which are beneficial for PS activation and BPA removal. The BPA degradation mechanism was elucidated via radical capture experiments, electron paramagnetic resonance spectroscopy, electrochemical analysis, density functional theory calculations, and high-performance liquid chromatography–mass spectrometry, which revealed that SO4•−, •OH, O2•−, 1O2, and electron transfer contributed to BPA removal. Additionally, the ecotoxicity of the intermediates was evaluated. The FeBCGs exhibited high stability and resistance to inorganic anions and natural organic matter. These findings may provide guidelines for the design and development of integrated microelectrolysis materials coupled with advanced oxidation processes for water treatment.