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

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 Pb2+ and Cd2+ from aqueous solutions. Furthermore, kinetics, equilibrium isotherms, and column studies were conducted. Modification of the raw chicory waste by CaCl2 increased the cation exchange capacity as well as the Pb2+ and Cd2+ 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 Pb2+ and Cd2+, respectively. Exchange of Pb2+ and Cd2+ ions with alkali metals (Na+ and K+) and alkaline earth metals (Ca2+ and Mg2+) onto the waste surface during the removal experiments indicated that the ion exchange could be the dominant mechanism for the removal of Pb2+ and Cd-2. In addition, the regeneration of raw and modified chicory waste loaded by Pb2+ and Cd2+ with distilled water was not possible, while eluting the waste using CaCl2, NaCl and HNO3 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.