Studies on the removal of phosphate in water through adsorption using a novel Zn-MOF and its derived materials

A novel zinc-based metal–organic framework, {[Zn3(atz)2(pda)2]·2(H2O)}n (Zn-MOF; Hatz is 5-aminote-1H-terazole; H2pda is malonic acid), was prepared using the solvothermal method. Carbonization of the prepared Zn-MOF was conducted under elevated temperatures to investigate its phosphate adsorption performance. Through pre-adsorption experiments, the optimal carbonization temperature of 500 °C was determined, yielding Zn-MOF-500. Besides, multiple characterization methods were used to analyze the properties of Zn-MOF and Zn-MOF-500 materials before and after the adsorption of phosphate ions. The results showed that the BET surface area of Zn-MOF-500 was 18.57 m2/g, which was 16.37 times larger than that of the BET surface area of Zn-MOF. At 25 °C, Zn-MOF and Zn-MOF-500 exhibited an adsorption capacity of 123.44 and 226.07 mg/g, respectively. Based on the adsorption isotherms and the adsorption kinetics, the adsorption of PO43- occurs via monolayer. X-ray diffractometry (XRD) and X-ray photoelectron spectroscopy (XPS) analysis showed that P was adsorbed on Zn-MOF and Zn-MOF-500 as the zinc hydrogen phosphate and zinc phosphate ions, respectively.