Construction of Microporous Lignin-Based Hypercross-Linked Polymers with High Surface Areas for Enhanced Iodine Capture

The development of highly efficient, green, and economical materials for radioactive iodine capture has great significance in the safe development of nuclear energy. Here, organosolv lignin (OL) extracted from poplar sawdust was first used to synthesize a series of microporous lignin-based hypercross-linked polymers (LHCPs). Specifically, lignin-based copolymers (LCPs) were synthesized by the grafted copolymerization of OL combined with 4-vinylbenzyl chloride and divinylbenzene, and then the in situ Friedel-Crafts reaction was performed with the structure of LCPs to obtain LHCPs with a high Brunauer-Emmett-Teller surface area (S-BET: 1076.32-1449.56 m(2)/g), hierarchical pore structure, and good stability. Interestingly, the polarity of LCPs and porosity of LHCPs can be well-controlled by adjusting the feeding amount of lignin. Taking advantage of abundant O-containing groups of the lignin skeleton as well as the high BET surface area of LHCPs, these lignin-based polymers were first applied to iodine adsorption, and LHCP-3 displayed an enhanced iodine vapor adsorption capacity of up to 253 wt % at 348 K and 1 bar. In addition, these LHCPs were also used for the adsorption of an iodine solution, and they exhibited a fast adsorption rate and good reusability, and adsorption isotherms can be better matched with Freundlich models. This study offered a feasible way to develop the fascinating microporous lignin-based polymers, which can not only increase the added value of lignin from biorefineries but also provide promising adsorbents for environmental remediation.