Investigation of the Sr2+ Ions Removal from Contaminated Drinking Water Using Novel CaO NPs@MOF-5 Composite Adsorbent

Abstract

In this research, nanoporous crystalline metal–organic framework-5 (MOF-5, Zn4O(BDC)3:BDC = 1,4-benzenedicarboxylate) has been appropriately synthesized through solvothermal method. Then, for the first time, calcium oxide nanoparticles (CaO NPs) as 10.4 wt% of unit were dispersed and deposited on the MOF-5 using impregnation method for the preparation the novel CaO NPs@MOF-5 composite adsorbent. The characterization study of samples performed by SEM–EDX, TEM, AFM, XRD, FTIR, XPS, solid state 13C MAS NMR and TGA techniques. The removal process of strontium-II (Sr2+) ions by the CaO NPs@MOF-5 composite was operated under variant experimental conditions including pH, adsorbent dose, contact time, initial concentration, and the adsorbent type at room temperature and the pursuant monitoring was accomplished via the ICP-AES technique. The adsorption isotherm models including Langmuir, Freundlich, Temkin and Harkins–Jura have also been applied. The experimental adsorption isotherm is successfully illustrated by the Freundlich model. The ICP-AES results confirmed the adsorption of Sr2+ on the composite active surface after 40 min at room temperature and the yield calculated as 99.34%. The reaction kinetic information was studied by utilizing the pseudo first and second orders kinetic models. The adsorption kinetics was in good consistency with the pseudo second order models. Furthermore, the evaluation of the thermodynamic parameters such as ΔG0, ΔH0 and ΔS0, specified that the adsorption process of Sr2+ was spontaneous and describes a physic-chemical adsorption properties and plus the exothermic basis of the adsorption.