Highly Flexible Interconnected Lis Porous Hydrogels with Self-Regulating Nanonetwork Structure for Marine Lithium Recovery

Abstract

LIS films, foams or granules have been fabricated to immobilize LIS to overcome powder loss for Li extraction from seawater. However, the practical application is still restricted by their low swell ability and poor flexibility to withstand harsh marine environment for a long time. Here, a highly elastic interconnected porous LIS nanocomposite hydrogel with tunable pore structure and flexibility is prepared by using LIS (λ-MnO 2 ) as a pore self-modifier during the in-situ fabrication of polypyrrole (PPy) and polyvinyl alcohol (PVA) interpenetrate hydrogel (IG) ( denoted as λ-MnO 2 @IG ). Due to the strong coordination/chelation and electrostatic interactions between λ-MnO 2 nanoparticle and polymer chains, the λ-MnO 2 @IG shows well-dispersed λ-MnO 2 nanoparticles and rich network structure. Even at marine environment (pH 8.3), the λ-MnO 2 @IG hydrogel exhibits superior Li adsorption performance (20.6 mg g -1 HMO), outperforming most adsorbents containing-LIS. Specially, the porous hydrogel is easy to recycle and exhibits super-stable cyclic Li extraction performance due to the further-improved pore size in continuous regeneration process . This study provides a self-regulating strategy to design LIS porous hydrogels with controllable porosity, high flexibility, and excellent cycle stability to address the growing Li-demanding challenges.

Keywords: nanonetwork hydrogel, Li+ ion-sieves, self-regulating pore, Flexible