Novel aluminum/lanthanum-based metal organic frameworks for phosphate removal from water

Excessive phosphate can lead to eutrophication and cause many ecological crises, which need to be effectively removed. Recently, metal-organic frameworks (MOFs) showed great effect on removing pollutants due to their special physicochemical features. In this study, La, Al and fumaric acid, as elements with higher affinity to phosphate and one environmentally friendly linker, respectively, were used to explore the environmentally friendly MOFs with high phosphate removal efficiency. Five F-Al/La MOFs with different mole ratio of Al and La ions were synthesized and characterized. F-Al and F-La has uniformly ordered particle structure and a sheet-like structure, respectively. According to the result of this study, the adsorption capacity of F-Al/La MOFs for phosphate was continuously enhanced by increasing La content. F-La exhibited the highest phosphate capture capacity of 101.80 mg P/g, which was almost twice of F-Al (53.11 mg P/g). Compared to F-Al, F-La showed good phosphate removal efficiency in a relatively wide pH range and natural water. In the further investigation, it indicated that the potential phosphate adsorption mechanisms employed by F-La mainly involved inner-sphere surface complexation and surface precipitation, while F-Al underwent more electrostatic interaction than F-La. This work developed one environmentally friendly F-La MOF material for phosphate removing from eutrophication water.