Effects of regulator ratio and guest molecule diffusion on VOCs adsorption by defective UiO-67: Experimental and theoretical insights

Abstract

• Optimum proportion of benzoic acid for synthesis of more defects UiO-67. • Defects, methyl and benzene ring enhance π-π interaction to promote VOCs adsorption. • Multiple experiments and DFT calculation analyze interaction between VOCs and MOFs. The harm that is caused by volatile organic compounds (VOCs) has attracted worldwide attention. In production, industrial processes such as fossil fuel combustion, plastics, and paints have caused complex and diverse VOCs emissions. Therefore, studying the phenomenon and influencing factors of typical VOCs adsorption is of practical significance for the treatment of multicomponent VOCs. In this work, defective UiO-67 was prepared by changing the amount of benzoic acid. Then, the adsorption performance was tested, and the adsorption kinetics were considered. The experimental results showed that the 67-ben-10 sample (for which the molar ratio of Zr 4+ to benzoic acid was 1:10) achieved the maximum toluene adsorption capacity (480 mg g −1 ), which was due to the presence of more adsorption sites, higher benzoate content, strong π-π stacking and excellent adsorption diffusion behavior. In addition, the adsorption properties of the 67-ben-10 benzene series (BTX: benzene, toluene, o-xylene, p-xylene and m-xylene) and acetone were further investigated. The results showed that the adsorption performance was related to the polarizability of the VOCs molecules, the method of pore entry and the molecular size. Finally, through desorption experiments, density functional theory (DFT) and kinetics, the binding energy was confirmed to play an important role in adsorption and diffusion.