Millimeter-sized MoS2@PDA@CER nanocomposite for efficient, selective, and scalable Hg(II) removal from water

Efficient decontamination of toxic mercury from water remains a critical challenge. MoS 2 nanoadsorbents exhibit significant advantages for mercury capture due to the strong soft-soft interactions between Hg(II) and sulfur. However, conventional MoS 2 nanosheets or MoS 2 -based nanocomposites are often hindered by practical limitations, including difficulty in separation and recovery, pore blockage, nanoparticle leaching, and high pressure drop in flow-through systems. Herein, we report a millimeter-sized nanocomposite (MoS 2 @PDA@CER) fabricated by coating MoS 2 nanosheets onto a cation exchange resin via a polydopamine (PDA) adhesive layer. The millimeter-scale architecture enables easy separation and superior hydraulics for flow-through operation. MoS 2 @PDA@CER exhibits broad pH applicability (1–8), ultra-high adsorption capacity (1168.18 mg/g at pH 5), rapid adsorption kinetics (equilibrium within 1 h), and exceptional selectivity toward Hg(II). These outstanding properties are attributed to the synergy between the unique millimeter-sized structure of the resin support and the strong affinity of MoS 2 for Hg(II). Furthermore, the nanocomposite demonstrates deep purification capability, effectively treating various trace mercury-contaminated waters to meet drinking water standards. It also shows excellent reusability, with no significant loss in adsorption capacity after 10 cycles. In fixed-bed column tests, MoS 2 @PDA@CER successfully treated ∼3000 BV of Hg(II)-spiked wastewater, with effluent complying with the Chinese integrated wastewater discharge standard (50 μg/L); notably, the first 900 BV even met the drinking water standard (1 μg/L). All the results indicate that MoS 2 @PDA@CER is a scalable and efficient adsorbent for the remediation of mercury-contaminated wastewater.