Mercury-containing wastewater poses a severe threat to human health owing to the extreme toxicity and bioaccumulation of Hg2+. However, the practical application of Hg2+ adsorbents is often limited by insufficient structural stability, recyclability, and selectivity under competitive ion conditions. Herein, a natural polymer-based, recyclable adsorbent was constructed by immobilizing silane-modified MoS2 nanosheets within a multicomponent carboxymethyl chitosan/poly(vinyl alcohol)/cellulose nanocrystal (CMC/PVA/CNC) network using glutaraldehyde as a cross-linker. This three-dimensional polymer framework effectively stabilizes MoS2 nanosheets while maintaining the accessibility of sulfur-containing active sites. Under optimal conditions (MS loading of 40% and pH 5.5), the adsorbent achieved a maximum Hg2+ adsorption capacity of 216.49 mg·g-1. More importantly, over 80% of the initial Hg2+ removal efficiency was retained after nine consecutive adsorption-desorption cycles, demonstrating excellent structural durability. The adsorbent exhibited pronounced selectivity toward Hg2+ in mixed-ion systems containing Cd2+, Cu2+, and Pb2+, with distribution coefficients 2 orders of magnitude higher than those of competing ions. Mechanistic investigations revealed that Hg2+ capture arises from cooperative coordination with -NH2, -OH, and -SH functionalities accompanied by redox transformation to Hg2SO4. This work highlights a rational immobilization strategy for designing stable and selective adsorbents suitable for complex heavy-metal wastewater remediation.
Li et al. (Fri,) studied this question.