Deciphering highly resistant characteristics to different pHs of oxygen vacancy-rich Fe2Co1-LDH/PS system for bisphenol A degradation

This first-attempt study explored interactive function of oxygen vacancies, transition metals, and surface hydroxyl groups for persulfate (PS) activation, at different pH conditions. Oxygen vacancy-rich Fe2Co1-LDHs was fabricated via calcination in hydrogen atmosphere. The Fe2Co1-LDH possessed the maximal concentration of oxygen vacancies and abundant hydroxyl groups for effective functioning according to the characterization through X-ray photoelectron spectroscopy (XPS) and electron paramagnetic resonance (EPR). The BPA-degrading efficiency in the LDHs/PS system indicated that Fe2Co1-LDH exhibited the most promising activated performance since oxygen vacancies could improve the catalytic efficiency to enhance electron transport phenomena between the Fe and Co. N-2 experiments proved that the presence of oxygen vacancies could promote the production of O-1(2) and O-2(center dot-). Phosphate and pH effect experiments showed the Fe2Co1-LDH/PS system stably maintained operation performance over a wide pH range for bisphenol A (BPA) removal with the effect of surface hydroxyl groups. Practical samples had little effect on the removal of BPA. According to the quenching experiments and EPR technology, SO4 center dot- was the main active radicals in acid and neutral conditions and apparently the OH center dot played the crucial role at alkaline pHs. Two different major reaction routes at different pH levels in the Fe2Co1-LDH/PS system for mechanisms of BPA degradation were proposed herein. The Chemical intermediates of BPA degradation were identified by gas chromatography-mass spectrophotometry (GC-MS) analysis, and degradation pathways were proposed for system optimization.