Nd-BTC metal-organic framework (MOF); synthesis, characterization and investigation on its adsorption behavior toward cesium and strontium ions

Abstract

In the present study, the synthesis and characterization of metal organic framework (MOF) was done with neodymium as a basic metal and benzene tricarboxylic acid (BTC) as a ligand with solvothermal method. In order to characterize the morphology and structure of the obtained adsorbent, XRD, FTIR, SEM, TG/DSC, and nitrogen adsorption/desorption methods were used. Then atomic absorption and ICP analysis is applied to determine the feasibility of metal-organic framework for sorption of cesium and strontium. Adsorption performance of Cs and Sr adsorbent was evaluated under the factors affecting adsorption experiments (initial solution pH, contact time, initial concentration of metal ion and temperature). The maximum adsorption capacity for cesium and strontium by adsorbent was obtained at pH 8. The kinetic data was analyzed by the pseudo-first-order, pseudo-second order, intra-particle diffusion, Elovich modified Freundlich kinetic models and the experimental data has a good correlation with the pseudo-second-order model. The equilibrium data were fitted to three isotherm models: Freundlich, Langmuir and Temkin. The Langmuir model was better described adsorption process and Maximum adsorption capacity was obtained 86 and 58 mg/g for Cs and Sr ions respectively. Thermodynamics parameters such as free energy change (ΔG° < 0), enthalpy (ΔH° > 0) and entropy (ΔS° > 0) were also calculated which represent spontaneous and endothermic nature of adsorption along with increasing irregularities at the solid-solution interface.