Aluminum-fumarate based MOF: A promising environmentally friendly adsorbent for the removal of phosphate

The removal of excessive phosphate from water is very important to avoid eutrophication. For this purpose, metal-organic frameworks (MOFs) have recently attracted great attention in phosphate adsorption due to their outstanding physicochemical features. However, most of the used MOFs in the adsorption of phosphate are based on those synthesized from organic ligands derived from petroleum sources such as tricarboxylic (BTC) and dicarboxylic acid (BDC), which can negatively impact the environment. Consequently, using stable MOF synthesized from an eco-friendly ligand is highly desired. In this work, Aluminum based fumarate MOF (Al-Fum) was used in the adsorption of phosphate from water and subsequently compared with other Al-MOF derived dicarboxylic acid (Al-BDC) and tricarboxylic acid (Al-BTC). The phosphate adsorption performance of the different synthesized Al-MOFs was evaluated with the help of different batch experiments related to the effect of adsorbent/adsorbate concentrations, the contact time, the pH and the temperature. Interestingly, Al-Fum displayed the highest adsorption capacity (67,62 mg P/g) compared to Al-BDC (47,58 mg P/g) and Al-BTC (23,17 mg P/g) at RT (22,2 °C). The regeneration of Al-Fum was tested for several cycles showing continuous adsorption capacity and stability. This work opens a new avenue toward the development and use of more environmentally friendly and reused MOFs for the removal of phosphate from water.