Defective UiO-66 embedded with biodegradable chelating agent iminodisuccinic acid (IDSA) for heavy metal ions removal

Given the severe threat posed by heavy metal pollution to both the ecological environment and human health, the development of green, efficient and sustainable adsorbents has become a major research focus. Herein, a novel heavy metal ions adsorbent (De-UiO-66-IDSA) was synthesized by functionalizing defect UiO-66 with the biodegradable chelating agent iminodisuccinic acid (IDSA). The effects of different factors on the adsorption of Pb²⁺, Cu²⁺ and Cd²⁺ by UiO-66-IDSA were investigated, including IDSA loading, contact time, adsorbent dosage and pH. Batch adsorption experiments showed that the adsorption kinetics followed PSO model, while the isotherm data were best described by the Langmuir model, indicating a monolayer chemisorption process. The maximum adsorption capacities for Pb²⁺, Cu²⁺ and Cd²⁺ were 377.40, 163.60, and 204.10 mg/g at 298 K, respectively and the adsorption was spontaneous and endothermic. Moreover, regeneration experiments demonstrated that the adsorbent retained over 75 % of its removal efficiency for all three metal ions after 5 cycles. These results highlight the great potential of De-UiO-66-IDSA as a green, high-performance, and a regenerable adsorbent capable of effectively eliminating heavy metal ions from aqueous media.