Lead and Cadmium removal from aqueous medium using coir pith as adsorbent : batch and fixed bed column studies

Abstract

Coir pith was used as an alternative to commonly available adsorbents for heavy metal ion removal from aqueous solutions. Batch and fixed bed column experiments were conducted to study adsorption characteristics of Cd and Pb onto coir pith. Coir pith is an effective adsorbent for Pb and Cd removal. The adsorbent dose, metal ion concentration and the solution pH affects the degree of adsorption. The maximum adsorption was observed at solution pH values above 5. The equilibrium data was satisfactorily fitted to Langmuir and Freundlich isotherms. Pb showed higher adsorption capacity compared to Cd under the experimental conditions. Kinetic studies revealed that Pb and Cd uptake was fast within first 10 to 15 min of contact time and data fits to pseudo second-order model. Breakthrough curve data fits to linear Bed Depth Service Time (BDST) model and bed capacities for Pb and Cd were 41 and 28 mg/g of coir pith respectively.