A mechanically robust chitosan-based macroporous foam for sustainable Se(IV) elimination from wastewater

The contamination of water resources by selenium (Se), particularly in the highly toxic Se(IV) oxidation state, poses a significant environmental and public health concern due to its detrimental impacts on humans and aquatic ecosystems. In this work, we report a novel composite foam (CFC) by incorporating chitosan (CS), cellulose nanofibers (CNF) and iron oxyhydroxide (FeOOH) nanoparticles through a one-pot fabrication process. The CFC foam features a three-dimensional porous structure, conferring both exceptional mechanical strength and superior adsorption performance for Se(IV), with a maximum equilibrium adsorption capacity of 90 mg/g achieved within 3 h. It maintained stable removal efficiency across a wide pH range and demonstrated strong resistance to interference from common anions and ionic strength variations. The primary adsorption mechanism involves electrostatic interactions and complexation between Se(IV) and functional groups presented in the CFC foam. Molecular dynamics simulations further confirmed the stability and effectiveness of Se(IV) adsorption at the molecular level. Additionally, CFC foam exhibited satisfactory practical applicability and durability, maintaining high Se(IV) removal performance over sequential adsorption processes. This study highlights the potential of CFC foam as an effective and sustainable material for Se(IV) remediation in wastewater, offering a promising solution for mitigating Se pollution and improving water quality.