Preparation and Adsorption Behavior of Ce(III)-MOF for Phosphate and Fluoride Ion Removal from Aqueous Solutions

The discharge of inorganic pollutants like phosphateand fluorideis a cause of mounting concern to the world due to the substantialenvironmental and human health risk. Adsorption is one of the mostcommon and affordable technologies widely utilized for removing inorganicpollutants such as phosphate and fluoride anions. Investigating efficientsorbents for the adsorption of these pollutants is extremely importantand challenging. This work aimed at studying the adsorption efficiencyof the Ce(III)-BDC metal-organic framework (MOF) for the removalof these anions from an aqueous solution using a batch mode. PowderX-ray diffraction (XRD), Fourier transform infrared (FTIR), thermogravimetricanalysis (TGA), Brunauer-Emmett-Teller (BET), and scanningelectron microscopy-energy dispersive X-ray analysis (SEM-EDX) techniquesevidenced the successful synthesis of Ce(III)-BDC MOF in water asa solvent without any energy input within a short reaction time. Theoutstanding removal efficiency of phosphate and fluoride was exhibitedat an optimized pH (3, 4), adsorbent dose (0.20, 0.35 g), contacttime (3, 6 h), agitation speed (120, 100 rpm), and concentration (10,15 ppm) for each ion, respectively. The experiment on the effect ofcoexisting ions demonstrated that SO4 (2-) and PO4 (3-) ions are the primary interferingions in phosphate and fluoride adsorption, respectively, while theHCO(3) (-) and Cl- ionswere found to have interfered less. Furthermore, the isotherm experimentshowed that the equilibrium data fitted well with the Langmuir isothermmodel and the kinetic data correlated well with the pseudo-second-ordermodel for both ions. The results of thermodynamic parameters suchas & UDelta;H & DEG;, & UDelta;G & DEG;,and & UDelta;S & DEG; evidenced an endothermic and spontaneousprocess. The regeneration of the adsorbent made using water and NaOHsolution showed the easy regeneration of the sorbent Ce(III)-BDC MOF,which can be reused four times, revealing its potential applicationfor the removal of these anions from aqueous environment.