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

Abstract

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.