YNTHESIS, CHARACTERIZATION AND SORPTION BEHEVIOUR OF Ce-MOF FOR THE REMOVAL OF PHOSPHATE AND FLUORIDE IONS FROM AQUEOUS SOLUTION

Abstract

The wastewater treatment industry has identified the discharge of inorganic anions such as phosphate and fluoride into water as a risk to the natural environment and human health. Among various methods used to remove phosphate and fluoride anions, adsorption is widely used because of its low cost, ease of use and simplicity. In this study, cerium-based organic metal frameworks was proposed as adsorbent to remove phosphate and fluoride ions from water.. The aim of this work was to study the capacity of Ce-MOF for the removal of phosphate and fluoride ions from aqueous solution using a batch adsorption method. Ce-MOF was synthesized by hydrothermal method and characterized using PZC, XRD, FTIR and TGA techniques. The maximum removal efficiency of phosphate and fluoride by Ce-MOF occurred at; pH ( 3, 4); Dose (0.2 g, 0.35 g) ; contact time (3 h, 6 h); agitation speed (120, 100 rpm) and concentration (10ppm, 15ppm) for each, respectively The isotherm experiment showed that equilibrium data were fitted both Freundlich and Langmuir isotherm models, but, Langmuir model was better fitted compared to Freundlich model which indicated the monolayer adsorption process takes place on the adsorbent. From kinetic study, the correlation coefficient (R2) close to 1, linear plot graph, indicates that the kinetic adsorption can be described very well fitted using pseudo-second-order kinetics equation both phosphate and fluoride ions. Thermodynamic parameters such as enthalpy change (∆Hº), free energy change (∆Gº) and entropy change (∆Sº) were studied, and the adsorption process of Ce-MOF was found to be endothermic, spontaneous and with high degree of randomness. The regeneration of the adsorbate was investigated by using water and NaOH solution, the result revealed that Ce-MOF can be easily regenerated and reused four times.