Constructing sponge-like structured molecularly imprinted composite membranes for acteoside separation

The separation performance of molecularly imprinted composite membranes (MICMs) for acteoside (ACT) was often limited by their microstructural design. This study proposed a novel strategy to enhance the performance by introducing hollow mesoporous carbon spheres (HMCs) into the MICM matrix, through which sponge-like structured molecularly imprinted composite membranes (SMICMs) were successfully constructed. In this structure, HMCs served two key functions: they induced surface roughening and pore formation in the membrane matrix, and also optimized the internal architecture of the membrane. Benefiting from the sponge-like structure, the SMICMs exhibited three major advantages: (1) the structure provided a large specific surface area, which significantly increased the surface density of ACT-specific imprinted sites (ACT-SISs) and effectively improved the adsorption selectivity; (2) the interconnected hierarchical pore network formed by HMCs, together with their intrinsic cavities, offered sufficient and easily accessible storage space for ACT molecules, leading to high adsorption capacity; and (3) the rough surface morphology and internal interconnected channels, acting in synergy with the abundant ACT-SISs and the multi-level cavities, remarkably enhanced the permeation selectivity for ACT molecules. Owing to these sponge-like structural features constructed primarily by HMCs, the SMICMs achieved an adsorption capacity of 177.3 mg g^-1 for ACT, an adsorption selectivity of 4.35, and a permeation selectivity of 9.62. The development of SMICMs offers a new approach for the efficient separation of natural products.