Synthesis of C/nZVI composites and its application in the remediation of cadmium - arsenic contaminated environments

Simultaneous remediation of cadmium (Cd) and arsenic (As) pollution is a great challenge due to the opposite chemical properties of Cd and As. In this study, carbon-supported nano-zero-valent iron (C/nZVI) was prepared through carbon thermal reduction and applied it to the remediation of Cd- and As-contaminated environments. The C/nZVI composites prepared with Fe–C ratio of 1:10 and pyrolysis temperature at 800 °C have better removal and immobilized effects on Cd and As pollution compared with other C/nZVI composites. Dissolved organic matter and nZVI in C/nZVI composites are involved in the adsorption of Cd and As. Arsenic exists on the surface of the C/nZVI composites in the form of H₂AsO₄⁻ and HAsO₄²⁻, while Cd exists on the surface of the materials in the form of CdCO₃, Cd–O and CdFe₂O₄. C/nZVI-10-800 significantly reduced the Cd and As content of Chinese cabbages (23.13% and 47.32% in aerial parts, respectively) during the remediation of As- and Cd-co-contaminated soils. This study demonstrated that C/nZVI composites are a promising material for Cd and As pollution remediation.