Highly defective UiO-66: One-pot synthesis and synergistic adsorption of bisphenol A

Highly defective UiO-66 was prepared using a one-pot solvothermal approach with benzoic acid as a defect modulator. • The pore structure and hydrophilicity of UiO-66 can be regulated by tuning the load of benzoic acid. • BPA adsorption by UiO-66-B3 is a spontaneous exothermic process dominated by monolayer chemisorption. • The excellent BPA adsorption performance of UiO-66-B3 arises from a synergistic process. UiO-66, a Zr-based metal-organic framework (MOF), shows great potential in adsorption, catalysis, water treatment, and chemical shielding. Defect engineering has been employed to further enhance its adsorption performance. Nevertheless, conventional defective UiO-66 suffers from time-consuming synthesis and fragile porous structure, and its adsorption capacity needs further improvement. In this study, a highly defective UiO-66 (denoted as UiO-66-BX, where X = 0, 1, 2, 3, 4, and 5) was synthesized using a one-pot solvothermal approach, with BA as the defect modulator to trigger competitive coordination. Its adsorption performance was demonstrated using bisphenol A (BPA). The results demonstrated that the adsorption data of the UiO-66-B3 for BPA in wastewater were well-fitted by the pseudo-second-order kinetic model and the Langmuir model, and both Δ G and Δ H were below 0, indicating that it is a spontaneous exothermic process dominated by monolayer chemisorption. Meanwhile, the theoretical adsorption capacity of the UiO-66-B3 can be up to 340.14 mg∙g −1 at 298.15 K. Additionally, adsorption by the UiO-66-B3 showed excellent tolerance to high ionic strength (variation in the adsorption capacity <7%) and good reusability (variation in adsorption capacity <10%). The excellent adsorption performance of the UiO-66-B3 can be attributed to a synergistic process involving mesopore-induced pore filling, hydrogen bonding between Zr-OH sites and phenolic -OH, coordination bonding between Zr 4+ and O in -OH, and π-π stacking of benzene rings. This study provides a promising strategy for the development of defect-rich UiO-66 for efficient pollutant removal. Download: Download high-res image (210KB) Download: Download full-size image