Adsorption of cadmium ion from aqueous solutions by copper-based metal organic framework: equilibrium modeling and kinetic studies

Abstract

In the present study, the adsorption behavior of copper-based metal organic framework (Cu-MOF) in the removal of cadmium ion (Cd 2+ ) from aqueous solution was investigated. The Cu-MOF prepared by solvothermal method was characterized by BET, FTIR, SEM and EDX techniques. Effect of adsorption parameters such as initial Cd 2+ concentration (20-100 mg/L), contact time (20-60 min) and adsorbent dosage (0.1-0.5 g) on the removal efficiency and equilibrium adsorption capacity was investigated at fixed pH and temperature. The results obtained from the batch mode adsorption studies revealed that at initial Cd 2+ concentration of 20 mg/L, contact time of 60 min and adsorbent dosage of 0.5 g, the removal efficiency and equilibrium adsorption capacity of Cd 2+ from the process were 98.62% and 1.9724 mg/g, respectively. The experimental data were evaluated by Langmuir and Freundlich isotherm models. The data fitted well with the Langmuir isotherm, and monolayer adsorption capacity of the Cu-MOF was 219.05 mg/g. The kinetic data were analyzed by using pseudo-first-order, pseudo-second-order and intraparticle diffusion models. The kinetic studies showed that pseudo-second-order model exhibited high correlation coefficients for all the initial Cd 2+ concentrations studied, thus indicating that the theoretical amount of Cd 2+ adsorbed agreed to the experimental values of Cd 2+ adsorbed.