A study on adsorption of cadmium(II) ions from aqueous solution using Luffa cylindrica

摘要

In the present study, the removal characteristics of Cadmium(II) through adsorption on Luffa cylindrica, as a natural adsorbent, under batch equilibrium and fixed-bed column experiments were investigated. The effects of pH, contact time, adsorbent dosage, and initial solution concentration on the uptake of metal ions by the adsorbent in batch operation were examined. Batch equilibrium data were used for linear fittings of the Langmuir and Freundlich isotherms. The adsorption behavior of Cd(II) ions fitted both isotherms but followed Langmuir isotherm most precisely (R-2 = 0.987), with a maximum monolayer adsorption capacity of 6.711 mg/g. The capacity of Luffa to adsorb Cd(II) in a fixed-bed column was investigated as well. The effect of operating parameters such as flow rate and inlet Cd(II) concentration on the sorption characteristics of Luffa was studied by assessing breakthrough curve. The data confirmed that the total amount of sorbed Cd(II) and equilibrium Cd(II) uptake decreased with increasing flow rate and increased with increasing inlet Cd(II) concentration. The Adams-Bohart model was applied to experimental data to predict the initial part of breakthrough curves and to determine the characteristic parameters of the column useful for process design. The results show that Luffa has high possibility to be used as effective and economical adsorbent for Cd(II) removal.