Mass transfer enhancement for rapid, selective extraction of pharmaceuticals by enlarging the microporous on isostructural zeolitic imidazolate Framework-8

Mixed pharmaceuticals with diverse structures in water can cause inevitable adverse impact to water environment. Selective removal and recognition for a specific one rapidly is of highly demand. Zeolitic Imidazolate Framework-8 (ZIF-8), which is a typical porous material, has been proved to be a promising material because of its good stability together with a high surface area and fine-tunable pore sizes. However, the adsorption performance for larger molecular sizes (>1nm) is hindered by the inherent microporous structure. Herein, we report a facile template-induced strategy to systematically synthesize a series of ZIF-8 based isostructural hierarchical porous adsorbent. By systematically investigating the adsorption for different pharmaceuticals with diverse chemical structures, a significant enhancement for initial adsorption rate (57.76 mg/g∙min) was obtained for ibuprofen and which is × 10.9 times higher than that of the pristine one (5.29 mg/g∙min), suggesting that both the unsaturated coordinated sites and the enlarged porous windows overcome the mass transfer bottleneck via generating hierarchical pores. By investigating eight pharmaceuticals with totally different chemical structures over the hierarchical porous ZIF-8, a high selectivity ranging from 6.12 mg/g to 216.32 mg/g can be observed. The mechanisms were explored by theoretical calculations using DFT method. The adsorption performance is evaluated in a dynamic adsorption experiment. This study gives a novel insight into fabricating hierarchical porous adsorbent for diverse micropollutants elimination selectively and rapidly.