Evaluation of the adsorptive capacity of peanut hull pellets for heavy metals in solution

This study assessed the potential of peanut hull pellets to capture metal ions from wastewater and compared their performance to that of raw peanut hulls and a commercial grade ion-exchange resin. The uptake of Cu2+, Cd2+, Zn2+, and Pb2+ onto these media was investigated using a system of standardized batch adsorbers under steady state and transient rate conditions. The influence of the pelletizing process on the rate of metal ion sorption was evaluated by comparing the rate and extent of metal ion uptake onto peanut hull pellets vs. raw peanut hulls. Although a slight reduction in rate of adsorption was apparent for metal ion adsorption onto the pellets, equilibrium capacity was unaffected. Peanut hull pellets are an effective adsorbent for metal ion removal. Though their capacity is lower than that of commercial grade ion-exchange resins, their low cost makes them an attractive option for the treatment of low-strength metal ion waste streams in once-through fixed bed applications. (C) 2000 Elsevier Science Ltd. All rights reserved.