Construction and properties of UiO-66-based bulk high-efficiency boron adsorbents

Recent research efforts have increasingly focused on the synthesis of high-efficiency boron adsorbents, particularly bulk MOFs-based materials rather than powders adsorbents. Herien, a novel GO/UiO-66 aerogel bulk adsorbent was successfully prepared using a facile solvothermal method combined with ascorbic acid thermal reduction. This adsorbent demonstrates effective boron removal from aqueous solutions at 0.08 M boron solution and addresses the challenge of recovering MOFs powders. Consequently, at an initial pH of 10, the adsorption capacity of the GO/UiO-66–4 aerogel reached as high as 81.7 mg/g, and adsorption equilibrium was achieved within 120 min. The pseudo-second-order model effectively described the adsorption kinetics with a correlation coefficient (R²) of 0.9997, suggesting that the adsorption process was chemisorption-dominated. Furthermore, both the Henry and Freundlich models accurately depicted the adsorption isotherm, indicating that the boron adsorption by UiO-66 was a spontaneous endothermic reaction. In addition, the critical limiting factors influencing the adsorption capacity of the adsorbent were investigated. The findings indicated that the active sites on the UiO-66 surface were the predominant factor determining its adsorption capacity. Importantly, this work offers significant insights into the development of bulk MOFs-based adsorbents, as the adsorbent exhibits high boron selectivity and maintains stability over 10 cycles.