Enhanced Heterogeneous Fenton-like Process for Sulfamethazine Removal via Dual-Reaction-Center Fe-Mo/rGO Catalyst

Abstract

A heterogeneous Fenton-like catalyst with single redox site has a rate-limiting step in oxidant activation, which limited its application in wastewater purification. To overcome this, a bimetallic doping strategy was designed to prepare a heterogeneous Fenton-like catalyst (Fe-Mo/rGO) with a double-reaction center. Combined with electrochemical impedance spectroscopy and density functional theory calculation, it was confirmed that the formation of an electron-rich Mo center and an electron-deficient Fe center through the constructed Fe-O-Mo and Mo-S-C bonding bridges induced a higher electron transfer capability in the Fe-Mo/rGO catalyst. The designed Fe-Mo/rGO catalyst exhibited excellent sulfamethazine (SMT) degradation efficiency in a broad pH range (4.8–8.4). The catalytic performance was hardly affected by inorganic anions (Cl−, SO42− and HCO3−) in the complicated and variable water environment. Compared to Fe/rGO and Mo/rGO catalysts, the SMT degradation efficiency increased by about 14.6 and 1.6 times in heterogeneous Fenton-like reaction over Fe-Mo/rGO catalyst. The electron spin resonance and radical scavenger experiments proved that ·O2−/HO2· and 1O2 dominate the SMT removal in the Fe-Mo/rGO/H2O2 system. Fe and Mo, as active centers co-supported on rGO, significantly enhanced the electron transfer between catalyst, oxidant, and pollutants, which accelerated the reactive oxygen species generation and effectively improved the SMT degradation. Our findings offer a novel perspective to enhance the performance of heterogeneous Fenton-like catalysts by accelerating the electron transfer rate in the degradation of organic pollutants.

Study and Application Status of Ultrasound in Organic Wastewater Treatment

“…There are multiple transition metal elements that can initiate the Fenton-like catalytic process, including Fe, Cu, Mn, and Pb [63,64], while Fe-based catalysts and Cubased catalysts are common ones. Fe-based Fenton-like catalysts consist of synthetic catalysts such as MnFe 2 O 4 /biochar, Fe-Mo/rGo [15], Fe/Cu@γ-Al 2 O 3 [16], and Fe/Acidmontmorillonite [65], iron ores, solid waste such as coal fly ash, slag, and gangue [6,[66][67][68][69], and zero-valent iron. Table 3 summarizes the system, reaction conditions, and effects of typical ultrasound and FE methods for degrading organic wastewater.…”

“…In order to effectively eliminate organic pollutants in wastewater, many methods have been explored, and they can be divided into a chemical oxidation degradation process [13], biochemical degradation process [14], and physicochemical degradation process. However, every method has shortcomings [15]. Against this backdrop, some physical fields such as an ultrasound field, MW field, and UV/visible light field were introduced to compensate for these shortcomings, thus enhancing the treatment efficiency of wastewater.…”