Iron (Fe) metal-organic frameworks: a new class of superior and sustainable phosphate adsorbents

Abstract To mitigate harmful algae blooms, chemicals are applied to the water that immobilize phosphate through adsorption. Metal-organic frameworks (MOFs) have recently emerged as a promising class of solid adsorbents for a wide variety of water pollutants, including phosphate. In the context of algae blooms however, limited knowledge exists regarding the performance of low-cost MOFs, their chemical stability in dilute phosphate concentrations and how they compare to other types of commonly used adsorbents. In this study, three iron based and low-cost MOFs were compared against commercial adsorbents in a relevant context. Overall, the MOFs exhibited a superior performance in terms of kinetics and adsorption capacity over a wide range of concentrations. The examination of the pore structure data revealed direct correlations with the adsorption kinetics. The comparison of the material cost and the adsorption capacity at ultra-low concentrations places these MOFs in a position to compete against commercial adsorbents. The exposure of the MOFs to dilute phosphate solutions resulted in negligible linker losses.