Efficient and Selective Removal of Hg(II) from Aqueous Solution by a Highly Stable Amino Isonicotinic-Based Coordination Polymer

The development of a stable, efficient, and highly selective Hg(II) adsorbent is important for sewage treatment and for human health. This study presents a new isonicotinic acid-based coordination polymer (CP-1-NH2), investigates its Hg(II) removal performance, and proposes a mechanism of Hg(II) removal by CP-1-NH2. A large number of uncoordinated amino groups are retained during the formation of the coordination framework with nicotinic acid groups, enabling the selective and efficient capture of Hg2+ ions. The maximum adsorption capacity is 116.32 mg/g. The environmentally friendly ligands avoid secondary pollution caused by S-containing compounds. CP-1-NH2 also resists interference by coexisting ions in aqueous solutions. CP-1-NH2 demonstrated a high removal performance during the entire adsorption process, which occurs in a single-crystal state. The regeneration performance was retained after multiple cycles. The possible adsorption mechanism was systematically verified through Fourier transform infrared transform and X-ray photoelectron spectroscopies. The amino-functionalized materials exhibit a high affinity for Hg(II). This work provides new design considerations for crystalline metal-organic framework adsorbents.