Metal-organic frameworks and their composites for the adsorption and sensing of phosphate

The adsorption and sensing of phosphate (P) are extremely appealing procedures to reduce and anticipate the effect of eutrophication. Recent advances in materials science enabled the design and development of new porous materials to be accurately controlled on the nanometer scale. In this context, one of the most attractive type of porous solids that have received tremendous interest in the last two decades is metal–organic frameworks (MOFs) which are currently under extensive investigation to tackle several environmental issues such as eutrophication caused mainly by the excessive use of phosphate fertilizers. The high surface area and unique degree of tunability of MOFs in terms of porosity, multiple functionalities and stability across wide ranges of pH and temperature imparted MOFs with unprecedented properties compared to other classical solids which are very suitable for both adsorption and sensing. In this perspective, we highlight the utilization of MOFs and their composites in the removal and sensing of phosphate from/in different mediums. The review article spotlights meritorious examples of different MOFs and their hybrid materials to provide the readers with a great understanding of the role of existing organic functions, metal nodes and the presence of defects in MOFs in the uptake and sensing of P and discuss how the presence of a second component with MOFs increases the adsorption efficiency as well as the sensing capability together with regeneration cycles, promoting thus the removal and identification of phosphate. It also explains the mechanism involved in both processes and provides a fair comparison with existing adsorbents and sensors. Finally, we will debate the limitations, challenges, and prospects of using MOFs in phosphate uptake and detection and how this can be applied to the real samples and industrial effluents.