Selective separation Li+/Co2+ via FCDI system with UiO-66-NH2 incorporated polyamide sulfonamide composite membrane and acid resistance evaluation

The recycling of lithium-ion batteries (LIBs) presents significant challenges due to the absence of robust acid-resistant membranes capable of selective ion separation under harsh acidic conditions, commonly encountered in hydrometallurgical processes. This study developed a novel PSA-BTSC (polysulfonamide with 1,3,5-benzenetrisulfonyl chloride) composite membrane integrated with UiO-66-NH 2 nanoparticles, aiming to enhance both acid resistance and ion separation performance. Experimental results demonstrated that the PSA-BTSC membrane achieved a Li+/Co 2+ separation factor of 28.02 and retained 85.8 % permeability for Li + while maintaining 91.1 % rejection for Co 2+ after 30 days of immersion in 1 M HCl, showcasing superior acid resistance compared to conventional PA-TMC (polyamide with 1,3,5-benzenetricarbonyl trichloride) membranes, whose Co 2+ rejection dropped drastically to 19.4 %. Surface charge analysis and pore size distribution indicated that PA-TMC membranes suffered partial hydrolysis and pore enlargement, resulting in a reduction of separation efficiency. In contrast, the sulfonyl groups in PSA-BTSC membranes conferred enhanced stability against acid-induced degradation. Additionally, density functional theory (DFT) simulations highlighted the higher activation energy barrier (2.63 eV) for sulfonamide bond hydrolysis compared to amide bonds (1.57 eV), emphasizing the superior stability of the PSA structure. These findings highlighted the superior stability and acid resistance of PSA-BTSC membranes, positioning them as promising materials for applications requiring high stability in acidic environments, such as the processing of lithium battery leachates.