Modeling and simulation of the continuous adsorption of ‎cadmium (II) ion by Luffa Cylindrica biosorbent using CFD-RSM ‎combined method ‎

Cadmium (II) is one of the most harmful heavy metal ions and its persistency in groundwater ‎has been an increasing issue for decades. This study aims to evaluate the adsorption of Cd (II) by ‎natural Luffa Cylindrica adsorbent using a computational fluid dynamics approach (CFD). After ‎validation of the numerical results with the experimental data, the impact of bed length and ‎porosity parameters on the adsorption rate was investigated. Furthermore, the impact of fluid ‎flowrate, initial cadmium (II) concentration, bed length, and bed porosity was investigated ‎using experimental design. Based on the optimization method, the optimum conditions were ‎found to be initial concentration, 50 mg/L; flow rate, 10.612 mL/min; bed porosity, 0.66; and ‎bed length, 14.51 cm. The maximum amount of cadmium ions adsorbed was 122.05 mg, and the ‎maximum equilibrium adsorption capacity was 20.21 mg/g. The study showed that the increase ‎in fluid flow rate and porosity led to a decrease in the amount of adsorption, while an increase ‎in the initial concentration and length of the bed resulted in an increase in the amount of ‎adsorption‏.‏