Facile fabrication of microstructure-tunable aluminum-based metal–organic frameworks for exceptional phosphorus recovery from water

Abstract

The recovery of phosphorus from phosphorus-contaminated water is of great significance to prevent the eutrophication of natural water and overcome the shortage of phosphorus resources. To increase the effectiveness of phosphorus removal from water, aluminum metal–organic frameworks (Al-MOFs) with different microstructures were synthesized in this study by varying the ratio of metal centers (Al) to organic ligands (terephthalic acid, BDC) in the precursor solution. For the precursor solution of a 10:1 M ratio of Al3+ to BDC, the synthesized Al-MOF exhibited the maximum phosphorus adsorption capacity (100.37 mg P/g). The pseudo-second-order kinetic model indicated a better fit for the experimental data obtained from the adsorption of phosphorus onto the synthesized Al-MOFs. The synthesized Al-MOFs appeared highly effective in removing phosphorus from water at an initial pH of 3.0 to 9.0. In addition, phosphorus adsorption onto Al-MOFs is not seriously affected by the presence of coexisting ions in water such as Ca2+, Mg2+, CO32–, HCO3–, NO3–, and Cl-. After five cycles of adsorption–desorption, the phosphorus recovery efficiency of the synthesized Al-MOFs decreased by only 15%. The phosphorus adsorption onto synthesized Al-MOFs is mainly governed by electrostatic interaction, complexation, and ligand exchange mechanisms.