Iron Carbon Catalyst Initiated the Generation of Active Free Radicals without Oxidants for Decontamination of Methylene Blue from Waters

Abstract

In conventional oxidation technologies for treatment of contaminated waters, secondary pollution of the aqueous environment often occurs because of the additional oxidants generated during the process. To avoid this problem, Fe/NG catalyst composites without additives were developed in this study for decontamination of methylene blue (MB) from waters. The Fe/NG catalyst, composed of carbon nitride and iron chloride (FeCl3∙6H2O), was prepared by high temperature pyrolysis. It is an exceptionally efficient, recoverable, and sustainable catalyst for degradation of organic matter. The morphological characteristics, chemical structure, and surface properties of the catalyst composites were investigated. The catalyst exhibited high MB removal efficiency (100%) within 30 min under ambient temperature and dark conditions. The experiments indicated that an MB degradation effect was also applicable under most acid–base conditions (pH = 2–10). The characterization results using electron spin resonance and analysis of intermediate products demonstrated that free radicals such as∙OH and∙O2− were produced from the Fe/NG composites in the heterogeneous system, which resulted in the high MB degradation efficiency. Moreover, the catalysis reaction generated reducing substances, triggering iron carbon micro-electrolysis to spontaneously develop a microcurrent, which assisted the degradation of MB. This study demonstrates the feasibility of Fe/NG catalysts that spontaneously generate active species for degrading pollutants in an aqueous environment at normal temperature, providing an attractive approach for treating organic-contaminated waters.

In Situ Coupling Carbon Defective C3N5 Nanosheet with Ag2CO3 for Effective Degradation of Methylene Blue and Tetracycline Hydrochloride

“…In order to clarify the degradation pathways of MB and TC-HCl, the intermediates of their photocatalytic processes were determined by LC-MS. Figure S3a show the m / z values of MB photodegradation at 90 min in the presence of a CNAC-10 catalyst, and intermediate signal peaks with different m / z values can be observed. Based on the LC-MS data and previous reports, two possible degradation pathways of MB were proposed ( Figure 10 a) [ 64 , 65 , 66 , 67 ]. In pathway I, the original MB ( m / z = 284) was converted to intermediate M1 ( m / z = 228) by S-Cl bond breaking and demethylation processes, followed by deamination and desulfonation reactions to produce intermediates M2 ( m / z = 173) and M3 ( m / z = 110).…”

Enhanced photocatalytic performance of a rGO-Ca2Fe2O5 nanocomposite for photodegradation of emergent pollutants

“…The pH of the effluent solution was adjusted using 0.05 M HCl and 0.05 M NaOH. The pH of the reaction system plays a major role for the photocatalytic performance because it may prevent the production of reactive radicals and reduce redox reactions on the surface of the photocatalyst [43][44][45] . The degradation efficiency of 5rGO-CFO for degradation of MB was analyzed in an acidic (pH 3) and basic (pH 9) reaction system, while the original pH of the MB solution was neutral (pH 7).…”