Efficient adsorption of lead ions by sulfur-rich conjugated microporous polymers aerogels with high selectivity

Lead is one of the primary sources of heavy metal pollutants that threaten the health of life, but it is extensively used in industrial production, especially for acid batteries. Developing effective and highly selective absorbents for lead ions in various water bodies is vital for human health and resource recovery. In this work, two hydrophilic and functionalized conjugated microporous polymer aerogels (SCMP) were rationally designed for selective removal of lead ions from aqueous solution via a two-step method, i.e., Sonogashira-Hagihara coupling copolymerization followed by sulfonation. As expected, the SCMP displayed an impressive anti-interference ability with selectivity for Pb²⁺ (70 %) over Cu²⁺ (1.9 %) and Zn²⁺ (6.1 %) in a complex multi-ion environment. Based on experimental results and theoretical density-functional theory (DFT) calculations, the proposed mechanism demonstrated that the outstanding selectivity arises from synergistic effects of electrostatic interactions, ion exchange and strong coordination between sulfonic acid groups and Pb²⁺. In real application, the monolithic SCMP as an efficient filter achieved over 91 % retention efficiency for Pb²⁺ within continuous multi-ion water, surpassing that of Cu²⁺ (22 %) and Zn²⁺ (33 %). Our work was expected to provide a platform for the design and fabrication of efficient adsorbents for removing heavy metal ions from wastewater and create more significant opportunities for functionality optimization of conjugated microporous polymer materials.