Cadmium and Lead Removal from Aqueous Solution by Grape Stalk Wastes: Modeling of a Fixed-Bed Column

Grape stalk wastes generated in the wine production process were used for the removal of cadmium and lead ions from aqueous solutions. The experimental breakthrough curves (BTC) were obtained from fixed-bed columns. Experiments were carried out to evaluate the influence of both inlet metal concentration and sorbent particle size. The experimental data were fitted to the Thomas model, a well-established fixed-bed sorption model. The theoretical sorption capacities obtained by the Thomas model were in good agreement with the breakthrough capacities determined from the sorption data. The CXTFIT code was used to determine the transport and sorption parameters of the convective-dispersive equation (CDE) and the two-site deterministic nonequilibrium (TSM/CDE) model by adjusting the models to the experimental breakthrough curves. The results showed that sorption capacities as well as both transport and sorption parameters were affected by the initial metal concentration as well as by the sorbent particle size.