Fabrication of lanthanum-modified MOF-808 for phosphate and arsenic(V) removal from wastewater

Abstract

Here, a lanthanum-modified metal-organic framework (La-MOF-808) fabricated by a solvothermal method was applied to remove phosphate or arsenic(V) from water. The physicochemical properties of the new adsorbent, including its morphology, pore size, and crystal structure, were determined. Notably, the incorporation of lanthanum slightly changed the structure of MOF-808, but La-BTC formed during loading. In addition, the factors affecting the adsorption performance (La: Zr molar ratio, temperature, concentration, ion strength, pH, and coexisting ions) were discussed. The results indicated that La-MOF-808 had the best adsorption performance for phosphate or arsenic(V) under a La: Zr mole ratio of 0.75. The reaction for capturing phosphate or arsenic(V) was rapid, and the maximum uptake capacities for phosphate and arsenic(V) were 287.71 mg g-1 and 217.54 mg g-1, respectively. XPS and FT-IR analyses confirmed that electrostatic interactions and hydroxyl group played major roles in the adsorption of phosphate or arsenic(V) by 0.75La-MOF-808. The absorbent could be regenerated after five adsorption-desorption cycles and showed only a negligible drop in its phosphate and arsenic(V) removal capacity. Therefore, 0.75La-MOF-808 is an effective adsorbent for phosphate and arsenic(V) and has a promising future for environmental remediation treatment.