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

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.