Constructing Ni4/Fe@Fe3O4-g-C3N4 nanocomposites for highly efficient degradation of carbon tetrachloride from aqueous solution.

Catalytic hydrodechlorination is one of the most potential remediation methods for chlorinated organic pollutants. In this study, Ni4/Fe@Fe3O4-g-C3N4 (NFFOCN) nanocomposites were synthesized for carbon tetrachloride (CT) removal and characterized by SEM, XPS and FTIR. The characterization results demonstrated that the special functional groups of g-C3N4, especially NH groups, effectively alleviated the aggregation of nanoparticles. In addition, the C and N groups of g-C3N4 enhanced the catalytic dechlorination of CT by providing binding sites. The experimental results showed that NFFOCN could effectively remove CT over a wide initial pH range of 3-9, and the CT removal efficiency reached 94.7% after 35 min with only 0.15 g/L of NFFOCN at pH 5.5. The Cl-, SO42-, and HCO3- promoted the removal of CT, while HA and NO3- had the opposite effect. Furthermore, good sequential CT removal by NFFOCN nanocomposites was observed, and the CT removal efficiency reached 77.3% after four cycles. Based on the identification of products, a possible degradation pathway of CT was proposed. Moreover, the main mechanisms regarding CT removal included the direct reduction of nZVI (about 40.51%), adsorption (around 34.79%), and hydrodechlorination of CT by Ni0 using H2 (about 19.40%).