Effect of Functional Groups on the I2 Sorption Kinetics of Isostructural Metal-Organic Frameworks

In this work, the effect of functional groups on I-2 sorption kinetics is investigated using two different types of isostructural metal-organic frameworks, UiO-66-X series (X = H, Br, NO2, NH2, (OH)(2), and (COOH)(2)) and M-2(m-DOBDC) series, (M = Co2+, Mg2+, and Ni2+; m-DOBDC4- = 4,6-dioxo-1,3-benzenedicarboxylate). Among the UiO-66-X series, UiO-66-(COOH)(2) exhibits the fastest sorption kinetics and the highest sorption capacity due to dipole-induced dipole interactions between carboxylic acid groups and I-2 molecules. In addition, faster I-2 chemisorption is observed in M-2(m-DOBDC) because of electrophilic aromatic substitution of m-DOBDC4- with I-2. The I-2 sorption mechanisms are further supported by fitting the I-2 adsorption kinetics data to pseudo-first-order and pseudo-second-order kinetic models.

Automated summary

The study investigated the effect of functional groups on I-2 sorption kinetics using two types of isostructural metal-organic frameworks. UiO-66-(COOH)2 showed the fastest sorption kinetics and highest sorption capacity, while M-2(m-DOBDC) displayed faster chemisorption due to electrophilic aromatic substitution. The mechanisms of I-2 sorption were further supported by fitting the data to pseudo-first-order and pseudo-second-order kinetic models.