Enhancing peroxymonosulfate activation of Fe-Al layered double hydroxide by dissolved organic matter: Performance and mechanism

In this study, peroxymonosulfate (PMS) activation of FeAl layered double hydroxide (FeAl-LDH) was enhanced by compounding dissolved organic matter (DOM). The characterization and catalytic performance of FeAl-LDH and DOM-LDH were investigated. The results revealed that the physicochemical properties of DOM-LDH were superior to FeAl-LDH: (i) The higher proportion of Fe(II) was found in DOM-LDH, mainly existed in the form of trans-coordinated octahedral Fe(II); (ii) DOM-LDH showed a flower-like morphology with larger specific surface area, pore width and pore volume; (iii) More functional groups and surface oxygen vacancies were found in DOM-LDH. Moreover, DOM promoted the process of PMS activation by accelerating Fe(III) reduction with humic acid-like compounds. The results of electron paramagnetic resonance (EPR) and quenching experiments indicated that more reactive oxygen species (ROS) were generated in DOM-LDH/PMS system, •OH was considered as the dominant ROS for Bisphenol A (BPA) degradation. As a result, the degradation efficiency for BPA (20 mg L-1) in FeAl-LDH/PMS system was increased from 60% to 93% within 60 min after the introduction of DOM. This work is expected to facilitate the design and application of Fe(II)/PMS system for environmental protection.