Bifunctional N/S-Coordinated Thiadiazole–Triazine Porous Organic Polymer for Efficient Hg(II) Immobilization in Aqueous–Soil Systems

Mercury (Hg) contamination in water and soil poses severe ecological and human health risks, yet conventional sorbents often suffer from limited capacity, selectivity, and stability. Here, we report a bifunctional porous organic polymer (AMTD-TCT) rationally constructed by covalently crosslinking 2-amino-5-mercapto-1,3,4-thiadiazole with trichlorotriazine, thereby integrating abundant sulfur and nitrogen coordination sites within a stable mesoporous framework. AMTD-TCT exhibits an ultrahigh Hg(II) adsorption capacity of 1257.7 mg g⁻¹, far exceeding most reported porous sorbents. Adsorption follows monolayer chemisorption, governed by strong S–Hg and N–Hg coordination and Na⁺/Hg²⁺ ion exchange, while hierarchical porosity ensures rapid diffusion and efficient utilization of active sites. The polymer maintains robust performance over a wide pH range and demonstrates strong retention with minimal desorption, underscoring its environmental durability. These findings highlight AMTD-TCT as a highly effective and scalable platform for Hg(II) remediation in complex aqueous–soil systems and illustrate a generalizable molecular design strategy for developing multifunctional porous polymers in advanced separation and purification technologies.