Enhanced degradation performance of p-chlorophenol in photo-Fenton reaction activated by nano-Fe0 encapsulated in hydrothermal carbon: Improved Fe(III)/Fe(II) cycle

In this study, heterogeneous Fenton-like catalyst, nano-Fe° encapsulated in hydrothermal carbon (Fe°/HTCC), was prepared via a green chemistry route, aiming at increasing the degradation efficiency of p-chlorophenol (4-CP) by controlling the stability of the catalyst and Fe(III)/Fe(II) cycling in the advanced oxidation process. The degradation of 4-CP by heterogeneous Fenton reactions was conducted with the assistance of visible light, which was monitored with the aid of the HPLC and total organic carbon analysis. The results revealed that Fe°/HTCC composite markedly enhanced both the degradation (100 %) and the mineralization efficiency (∼73.9 %) for 100 mg/L 4-CP within 60 min at pH 4.0. More importantly, the catalyst presented a high stability to resist the side oxidation, where the removal efficiency was maintained even after 5 successive cycling experiments. Electron spin resonance confirmed that in the presence of both HTCC and visible light irradiation greatly enhanced the production of •OH for the degradation and mineralization of 4-CP, which can be attributed to the enhancement of Fe(III)/Fe(II) cycling. This study paves a new way toward the rational design of Fe°–carbon composites as heterogeneous Fenton-like catalysts for potential applications into wastewater treatment.