Aspartic acid derivative-based MOFs: A promising green material for simultaneous removal of phosphorus and arsenic(V) in contaminated spring water

Abstract

Metal-organic frameworks (MOFs) based on amino acids and their derivatives are biocompatible and environmentally friendly and have excellent practical application value in wastewater treatment. In this work, four MOFs based on aspartic acid derivatives were synthesized using Zr(IV) as the central ions and aspartic acid, succinic acid, fumaric acid, and malic acid as organic ligands. These were used for the simultaneous removal of phosphorus and arsenic from wastewater. The results showed that the maximum adsorption capacities of the aspartic acid-based Zr-asp MOF for phosphorus and arsenic(V) were 88.30 mg P g−1, 109.75 mg As g−1, respectively, in a single system, and 32.00 mg P g−1 and 59.75 mg As g−1, respectively, in a binary system of coexisting phosphorus and arsenic; these capacities were over a broad pH range of 5.0–9.0. Also, Zr-asp can be recycled at least 4 times. The Langmuir isothermal adsorption model and pseudo-second-order model can be employed to describe the adsorption behavior of phosphorus and arsenic(V) well on the MOFs based on aspartic acid derivatives in both the single-pollutant and two-pollutant systems. The mechanism of phosphorus and arsenic(V) reaction on MOFs was mainly electrostatic attraction and coordination reaction accompanied by ligand exchange, and the hydroxyl group on the surface of the material plays a key role. All the results indicated that the synthesized MOFs based on aspartic acid derivatives are ideal eco-friendly candidates for phosphorus and arsenic(V) removal in complex actual bodies of water.