[Dynamic adsorption of cadmium (II) in water on modified peanut shells]

Peanut shells modified by potassium permanganate were used as absorbents for cadmium (II) removal in a fixed bed. The effects of influencing parameters such as bed height (ranging between 30 and 50 cm), initial concentration (ranging between 0.55 and 11.00 mg x L (-1)) and influent flow rate (ranging between 15.11 and 37.00 mL x min(-1)) were studied and the corresponding breakthrough curves were obtained. This result indicated that the column packed with modified peanut shells had good adsorption properties for cadmium (II) removal. In the initial adsorption stage cadmium (II) outflow concentration was less than 0.001 mg x L(-1). According to different operating conditions the operation time reached 2-62 h and the removal rate was above 54%. The height of mass transfer zone was primarily driven by initial concentration and influent flow rate. The height of mass transfer zone kept substantially unchanged and the breakthrough time increased with the increase of bed height. The height of mass transfer zone increased and the breakthrough time decreased with the elevated initial concentration and influent flow rate. The bed depth service time (BDST) model was used to fit the experiment data resulting in a good effect with R2 > 0.99 under low concentration. The operation time can be accurately predicted using the BDST model.