Monolithic Co-doped UiO-66-OH metal-organic gels for removal of tetracycline from water

Abstract

Metal-organic frameworks (MOFs) have become a focal point of interest owing to their ability to remove contaminants from wastewater. However, the typical powder form of MOFs is difficult to recover after use, which hinders their practical application. In this research, UiO-66-OH gel was synthesized at room temperature. On this basis, Co was doped into UiO-66-OH gel to obtain a series of Co@U-OH-X composites. The [email protected] exhibited an adsorption capacity for TC that was 5.1 times higher compared to the UiO-66-OH gel. Furthermore, the influence of pH, coexisting ions, humic acid, and original concentration of TC on the adsorption of [email protected] was examined. The composite materials demonstrated an exceptional capacity to adsorb TC (182.31 mg g⁻¹), which surpassed the performance of numerous previously documented adsorbents. The pseudo-second-order kinetic model and the Freundlich isotherm model efficiently accounted for the adsorptive interaction. Thermodynamic adsorption analyses indicated that the interaction occurred spontaneously and accompanied by heat absorption. After four cycles, there was only a 12.7 % reduction in the removal rate of TC, which suggested that the composite materials were recyclable. [email protected] showed remarkable adsorption capacity even in settings with minimal TC concentration. The exceptional adsorptive performance, superior recyclability and aqueous stability established Co@U-OH-X composites as a viable adsorbent contender for eliminating TC.