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

Mitin Belaye; Abi M Taddesse; Endale Teju; Manuel Sanchez-Sanchez; Jemal M Yassin

doi:10.1021/acsomega.3c02290

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

ACS Omega. 2023 Jun 16;8(26):23860-23869. doi: 10.1021/acsomega.3c02290. eCollection 2023 Jul 4.

Authors

Mitin Belaye¹, Abi M Taddesse¹, Endale Teju¹, Manuel Sanchez-Sanchez², Jemal M Yassin³

Affiliations

¹ Department of Chemistry, Haramaya University, P.O.Box 138, 138 Dire Dawa, Ethiopia.
² Instituto de Catálisis y Petroleoquímica (ICP), CSIC, C/Marie Curie 2, 28049 Madrid, Spain.
³ Department of Chemistry, Debre Berhan University, P.O.Box. 445, 445 Debre Berhan, Ethiopia.

Abstract

The discharge of inorganic pollutants like phosphate and fluoride is a cause of mounting concern to the world due to the substantial environmental and human health risk. Adsorption is one of the most common and affordable technologies widely utilized for removing inorganic pollutants such as phosphate and fluoride anions. Investigating efficient sorbents for the adsorption of these pollutants is extremely important and challenging. This work aimed at studying the adsorption efficiency of the Ce(III)-BDC metal-organic framework (MOF) for the removal of these anions from an aqueous solution using a batch mode. Powder X-ray diffraction (XRD), Fourier transform infrared (FTIR), thermogravimetric analysis (TGA), Brunauer-Emmett-Teller (BET), and scanning electron microscopy-energy dispersive X-ray analysis (SEM-EDX) techniques evidenced the successful synthesis of Ce(III)-BDC MOF in water as a solvent without any energy input within a short reaction time. The outstanding removal efficiency of phosphate and fluoride was exhibited at an optimized pH (3, 4), adsorbent dose (0.20, 0.35 g), contact time (3, 6 h), agitation speed (120, 100 rpm), and concentration (10, 15 ppm) for each ion, respectively. The experiment on the effect of coexisting ions demonstrated that SO₄^2- and PO₄^3- ions are the primary interfering ions in phosphate and fluoride adsorption, respectively, while the HCO₃^- and Cl^- ions were found to have interfered less. Furthermore, the isotherm experiment showed that the equilibrium data fitted well with the Langmuir isotherm model and the kinetic data correlated well with the pseudo-second-order model for both ions. The results of thermodynamic parameters such as ΔH°, ΔG°, and ΔS° evidenced an endothermic and spontaneous process. The regeneration of the adsorbent made using water and NaOH solution showed the easy regeneration of the sorbent Ce(III)-BDC MOF, which can be reused four times, revealing its potential application for the removal of these anions from aqueous environment.