Structural Defect Construction of Acid and Iron Dual-Modified UiO-66-NH2 for Enhanced Arsenic Capture in Wastewater

In this paper, UiO-66-NH 2 was synthesized by a solvothermal method. Two defects were induced by the introduction of an acid modifier and an iron source during synthesis. The effect of the acid modifier on the degree of defects and adsorption properties of the material was investigated by adjusting the type of acid modifier. The results showed that the addition of Fe and benzoic acid yielded the largest specific surface area in UiO-66-NH 2 with abundant defect structures. This enabled Fe-UiO-66-NH 2 -BA to achieve 78.83% arsenic removal within 60 s. The adsorption process followed pseudo-second kinetics and the Langmuir isothermal model. Notably, the adsorption capacity of Fe-UiO-66-NH 2 -BA for arsenic in wastewater at pH 11 (2010 mg/g) was superior to those of most of the reported MOF adsorbents. The excellent arsenic adsorption capacity can be attributed to the formation of free Lewis acid sites and ligand complexation by MOF deletion linkage defects, and the adsorbent can still maintain > 80% adsorption capacity after five cycles of regeneration. In conclusion, Fe-UiO-66-NH 2 -BA, as an efficient adsorbent for efficient capture of arsenic from wastewater, provides a new concept for water purification technology.