S-O dual-site coordination and spatial confinement of tartaric acid modified MoS2 anchored on sugarcane bagasse biochar for efficient removal of Pb2+ ions from water

Lead (Pb 2+ ) pollution in industrial wastewater poses severe threats to human nervous system and ecological security due to its high toxicity, bioaccumulation and non-biodegradability. Although MoS 2 nanosheets exhibit excellent affinity for Pb 2+ , their adsorption performance is constrained by nanosheet stacking and limited accessible active site separation performance. Herein, tartaric acid (TA)-functionalized MoS 2 nanosheets were confined within a sugarcane bagasse-derived biochar (BC) scaffold to construct TA-MoS 2 /BC. The porous carbon framework suppresses MoS 2 nanosheet restacking and creates accessible mesoporous channels for Pb 2+ transport, while TA introduces oxygen-containing groups that cooperate with sulfur sites for strong Pb 2+ binding. TA-MoS 2 /BC exhibited a high Langmuir adsorption capacity of 1073.27 mg·g −1 , together with a kinetic adsorption capacity of 726.60 mg·g −1 , which was 1.47 and 2.44 times higher than pure TA-MoS 2 and raw biochar, respectively. After five adsorption-desorption cycles, the composite retained 77.8% of its initial adsorption capacity, demonstrating satisfactory reusability. XPS and DFT analyses confirmed that adjacent S/O dual sites dominated Pb 2+ capture, showing a low adsorption energy of −5.24 eV and charge transfer of 1.068 e. Intraparticle diffusion analysis revealed a multi-stage mass-transfer process, and TA-MoS 2 /BC showed the highest initial diffusion rate constant of 48.25 mg·g −1 ·h -1/2 , confirming that the confined porous structure promoted Pb 2+ migration toward internal active sites. This work provides a confinement-coordination dual-regulation strategy for Pb 2+ removal while offering a value-added route for converting sugarcane bagasse waste into a functional carbon scaffold.