Fe-MOF-derived carbon compounds as catalysts for trichloroethylene degradation via persulfate oxidation: Role of precursor template and pyrolysis temperature

Abstract

Trichloroethylene (TCE) commonly exists in contaminated water as a persistent toxic pollutant. The advanced oxidation of persulfate (PS) is a promising method for degrading organic pollutants. Heterogeneous Fe-carbon composites prepared by pyrolysis with metal–organic frameworks (MOFs) have attracted attention. However, the intrinsic relationship between the physicochemical properties and catalytic performance of MOF-derived carbon compounds via PS is unclear. This study investigates TCE removal by Fe-MOF-derived carbon (MFC) with PS. The effects of the precursor template structure, pyrolysis temperature, and coexisting substances on TCE removal over the MFC/PS system are examined. Fe-MOF-derived from different precursor templates presented different TCE removal rates of 75.2–85.0%. The pyrolysis temperature of MFC alters the pore size, phase composition, and other properties, thereby affecting electron transport in the materials and catalyzing the degradation process. The total TCE removal reached 85.8% with MFC600, derived from MF88B and pyrolyzed at 600 ℃. This catalyst demonstrated excellent performance for PS degradation over a wide pH range (3−9). Moreover, free-radical and nonradical pathways coexist in the MFC600/PS system. During the TCE degradation process, oxygen vacancies, Fe species (Fe0, Fe3N, Fe3C, and Fe3O4), and N species (pyridinic N and graphitic N) were active centers in the material and played a major role in catalytic degradation. They participated in the subsequent generation of HO•, SO4•-, and •O2-, and 1O2. Furthermore, a possible degradation mechanism is proposed. This study elucidates the control of the physicochemical properties of carbon-based catalysts by exploiting MOF diversity.