摘要
Forward osmosis (FO) has emerged as a promising technology for lithium resource recovery owing to its low energy consumption. However, conventional FO membranes, typically featuring thick separation layers and defect-prone porous structures, suffer from low lithium recovery rates and processing efficiency. Herein, a thermos-responsive UiO-67-PNIPAM composite was constructed as a functional interlayer to dynamically regulate aqueous-phase monomer transport during interfacial polymerization. By leveraging the temperature-responsive nature of PNIPAM and controlling the organic-phase temperature, a vertical temperature gradient was established within the interlayer due to uneven heat transfer. In the upper, warmer region, PNIPAM adopts a collapsed conformation with reduced amide accessibility, exhibiting weak interaction with m-phenylenediamine, thereby enabling rapid monomer release. In the lower, cooler region, extended PNIPAM chains, with amide groups fully exposed, enhance interactions with m-phenylenediamine and hinder its diffusion to the reaction interface. This synergistic regulation promoted a self-terminating IP process, culminating in an ultrathin and dense separation layer. Furthermore, elevated temperature facilitated the escape of dissolved gases from both phases, leading to the formation of pronounced ridge-and-valley structures on the separation layer. This morphology increased the effective water permeation area and water storage capacity. As a result, the UiO-67-PNIPAM interlayer membrane achieved a water flux of 28.30 L m −2 h −1 in FO mode, representing a 100.28% improvement over the conventional membrane. Its reverse salt flux was significantly reduced to 1.44 g m −2 h −1 , a decrease of 47.26%. In lithium recovery tests, the membrane exhibited a high lithium recovery rate, demonstrating its strong potential for efficient lithium extraction.
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