High-efficiency removal of Cd(ii) and As(iii) from irrigation water using a S-Fe-C composite: performance and mechanisms

Addressing Cd(ii) and As(iii) pollution in agricultural irrigation is crucial for ecological and public health protection. This study introduces a S-Fe-C composite (SFC) to improve Cd(ii) and As(iii) removal from irrigation water. Characterization showed homogeneous S-nZVI nanoflake distribution within BC, enhancing adsorption capacities to 405 mg g-1 for Cd(ii) and 349 mg g-1 for As(iii). The adsorption process adhered to pseudo-second order kinetics and the Langmuir isotherm. BC can prevent S-nZVI aggregation and enhance electron mobility. Ca2+ and Mg2+ reduced Cd(ii) removal, whereas As(iii) and PO43- facilitated it. The efficacy of SFC stemmed from chemical precipitation, surface complexation, ion exchange, oxidation and Fe-Cd-As complex formation. Remarkably, SFC maintained its magnetic properties after five cycles, indicating its potential for recyclability. These results demonstrate the great potential of SFC as a functional material for simultaneous remediation of cadmium-arsenic contaminated irrigation water, which is critical for agricultural productivity and environmental health.