Synthesis of a novel magnetic biomass-MOF composite for the efficient removal of phosphates: Adsorption mechanism and characterization study

The adverse effects of eutrophication have prompted the use of various remediation techniques for phosphate (PO 4 3– ) removal owing to it being the major causative agent. Herein, the influence of different solvents and ratios of 2-aminoterepthalic acid on the efficiency of magnetic biomass metal–organic framework composites based on the in situ growth of NH 2 -MIL-101 (Fe) onto magnetized peanut husks towards PO 4 3– removal was assessed via the adsorption technique. The magnetic biocomposite labelled as MPN@NH 2 -MIL-101 (Fe) exhibited the best efficiency owing to its mesoporous structures and presence of abundant oxygen and nitrogen possessing functional groups. Adsorption results confirmed MPN@NH 2 -MIL-101 (Fe) to have a high adsorption capacity of (14.0 ± 0.3) mg·L −1 at a PO 4 3− concentration of 20 mg·L −1 with an associated high stability within pH 2–10. The adsorption kinetics for the process was well described by both Elovich and pseudo-second-order kinetic models and was mediated by both internal diffusion and liquid film diffusion. The Temkin and Freundlich models fitted the equilibrium data well signifying occurrence of both physical and chemical adsorption on a heterogeneous surface. It is concluded that MPN@NH 2 -MIL-101 (Fe) is a promising adsorbent for the effective removal of phosphate from a water body.