Highly efficient adsorption of thorium(iv) from aqueous solutions by functionalized UiO-66 with abundant phosphonic acid active sites

Abstract

This study introduces UiO-66-PO₃, a novel functionalized metal–organic framework (MOF) tailored for efficient thorium separation and enrichment from wastewater. UiO-66-PO₃ was synthesized by amination reaction between UiO-66-NH₂ and 2-carboxyethylphosphonic acid. Comprehensive characterization techniques confirmed its successful synthesis and revealed its unique properties. UiO-66-PO₃ exhibited a remarkable theoretical maximum adsorption capacity of 320.0 mg g⁻¹ for Th(IV) under optimized conditions. Its exceptional hydrophilicity significantly enhanced the adsorption capacity compared to UiO-66-NH₂. Furthermore, UiO-66-PO₃ retained over 89% of its initial adsorption capacity for Th(IV) after five adsorption–desorption cycles, highlighting excellent regeneration capabilities. UiO-66-PO₃ emerges as a promising adsorbent for thorium separation due to its high adsorption capacity, regeneration performance, and tunable properties.