Pore-expanded UiO-66 pellets for efficient bisphenol A adsorption

Pore expansion of the microporous metal–organic frameworks (MOFs) has caused most attraction in water treatment, but it is still challenging for MOFs shaping during the industrialization progress. Herein, pore-expanded UiO-66 pellet was fabricated to efficiently adsorb bisphenol A (BPA), which comprises the hierarchically porous UiO-66 (HP-UiO-66) powders well-distributed in the alginate-Ca²⁺ network. The mesopore percentage of HP-UiO-66 can be controlled by selective thermolysis of the hemilabile linker 2-nitroterephthalic acid (NO₂-BDC) for the first time. The N₂ adsorption/desorption tests show that the fabricated UiO-66 pellets well preserved the porosity of the original 0.25HP-UiO-66 powders, and the UiO-66 pellets had the excellent adsorption performance towards BPA with adsorption capacity up to 235.1 mg/g under neutral condition. Besides, the mechanism for BPA adsorption was revealed to be Zr-O bonding and π-π interaction by the analysis of X-ray photoelectron spectroscopy (XPS), and hydrogen bonding was simulated by density functional theory (DFT) calculation. Moreover, it was found that 1 g of the UiO-66 pellets with pore expansion can decontaminate >3 L water containing 100 mg/L BPA from continuous stream, and the high regenerative rate indicates the future industrial applications.