Preparation and characterization of novel bio ion exchanger from medicinal herb waste (chicory) for the removal of Pb2+ and Cd2+ from aqueous solutions

Abstract The ion exchange method has great potential for the removal of heavy metal ions from aqueous solutions. In this study, after the pre-selection experiments among 14 medicinal herb wastes, the ion exchange capacity of the raw chicory waste and its modified forms were evaluated for the removal of Pb 2+ and Cd 2+ from aqueous solutions. Furthermore, kinetics, equilibrium isotherms, and column studies were conducted. Modification of the raw chicory waste by CaCl 2 increased the cation exchange capacity as well as the Pb 2+ and Cd 2+ removal efficiency. The maximum adsorption capacities were increased from 103.1 and 53.8 mg g −1 by raw chicory waste to 123.5 and 64.5 mg g −1 by modified chicory waste for Pb 2+ and Cd 2+ , respectively. Exchange of Pb 2+ and Cd 2+ ions with alkali metals (Na + and K + ) and alkaline earth metals (Ca 2+ and Mg 2+ ) onto the waste surface during the removal experiments indicated that the ion exchange could be the dominant mechanism for the removal of Pb 2+ and Cd 2 . In addition, the regeneration of raw and modified chicory waste loaded by Pb 2+ and Cd 2+ with distilled water was not possible, while eluting the waste using CaCl 2 , NaCl and HNO 3 could effectively recover both metals. It was concluded that the prepared bio ion exchanger from chicory waste could be a promising and low-cost alternative to synthetic resins for the removal of heavy metals from the water and wastewater.