Introduction of hydrogen bond recognition sites in ZIF‐71 for effective separation of bio‐diols in aqueous solutions

Abstract

AbstractThe bio‐based diols 1,3‐propanediol (1,3‐PDO) and 2,3‐butanediol (2,3‐BDO) can form strong hydrogen bonds with water, which increases the separation difficulty of diols in aqueous solutions. Herein, a series of mixed‐linker ZIF‐71‐clnImx samples with hydrogen bond–van der Waals (vdW) dual recognition sites have been constructed using 4‐chloro‐5‐nitroimidazole (clnIm) linkers to substitute partially for the original 4,5‐dichloroimidazole (dclIm) linkers of the ZIF‐71 framework. The experimental and calculated results show that ZIF‐71‐clnImx with appropriate clnIm substitution proportion (x = 7.6 and 12.8 mol%) can strengthen the interaction between ZIF‐71‐clnImx and 2,3‐BDO and enhance the adsorption and mass transfer of 2,3‐BDO, thus achieving the efficient separation of 2,3‐BDO/1,3‐PDO. Molecular simulation results further verify that 2,3‐BDO can simultaneously form strong H bonds with the –NO2 of the clnIm linker and weak vdW interactions with the –Cl of the dclIm linker, which are the mixed recognition sites for 2,3‐BDO adsorption intensification in aqueous solution for ZIF‐71‐clnImx.