Modification of ZIF-8 with triethylamine molecules for enhanced iodine and bromine adsorption

Abstract

We report a new way to enhance halogen capping properties of ZIF-8 and to protect its structure in a slightly acidic medium. We observed that triethylamine additive in hydrothermal conditions results in modification of the ZIF-8 structure. Triethylamine molecules, which are trapped inside pores, increase the rate of iodine sorption both from hexane and methanol solutions. Moreover, the solution of iodine in methanol has an acidic medium, and it leads to the decomposition of non-modified ZIF-8 sample, while sample obtained in water with triethylamine preserve structure and effectively adsorb iodine. However, bromine molecules were capped by both ZIF-8 samples after 5 min of contact. It makes an eco-friendly scalable hydrothermal synthesis of ZIF-8 more attractive because it combines high crystallinity and porosity of obtained materials with modifications allowed to enhance iodine capping properties and chemical stability.