Amino acid assisted templating synthesis of hierarchical zeolitic imidazolate framework-8 for efficient arsenate removal.

We report the strategy of using the cationic surfactant cetyltrimethylammonium bromide (CTAB) and amino acid L-histidine (His) as co-templates to produce hierarchical ZIF-8 in an aqueous system at room temperature. The hierarchical ZIF-8 had both meso- and microporous structure, resulting in a high mesopore volume as well as specific surface area which can be controlled by the synthesis conditions. We put forward the hypothesis for the formation of a mesoporous structure and the enhancement of the porosity of ZIF-8 that the histidine plays a key role on the stabilization of CTAB micelles and avoiding the production of unexpected by-products therefore promotes the fabrication of pure phase ZIF-8 containing the mesopores interconnected with micropores. The prepared hierarchical ZIF-8 exhibited an excellent performance as a new kind of porous absorbent for efficient removal of the toxic arsenate.