Multicomponent Polymer Network Immobilizing MoS ₂ Nanosheets for Stable Hg ²⁺ Capture under Competitive Ion Conditions

Mercury-containing wastewater poses a severe threat to human health owing to the extreme toxicity and bioaccumulation of Hg 2+ . However, the practical application of Hg 2+ 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 MoS 2 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 MoS 2 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 Hg 2+ adsorption capacity of 216.49 mg·g –1 . More importantly, over 80% of the initial Hg 2+ removal efficiency was retained after nine consecutive adsorption–desorption cycles, demonstrating excellent structural durability. The adsorbent exhibited pronounced selectivity toward Hg 2+ in mixed-ion systems containing Cd 2+, Cu 2+, and Pb 2+, with distribution coefficients 2 orders of magnitude higher than those of competing ions. Mechanistic investigations revealed that Hg 2+ capture arises from cooperative coordination with –NH 2, −OH, and –SH functionalities accompanied by redox transformation to Hg 2 SO 4 . This work highlights a rational immobilization strategy for designing stable and selective adsorbents suitable for complex heavy-metal wastewater remediation.