Stability and Reusability of Magnetic-Cored Dendrimers for Heavy Metal Adsorption

Abstract

This thesis deals with the study of the stability and reusability of magnetic-cored dendrimers (MDs) for heavy metal adsorption. MDs terminalized with amine groups were synthesized, characterized, and investigated to adsorb heavy metal ions. Hydrochloric acid was chosen as desorption agent to evaluate the regeneration performance. The affinity order of adsorption on the MD was Pb2+> Ni2+> Cd2+and the different preference arose from the dissimilar electro-negativity of the heavy metal(Pb2+:2.33, Ni2+:1.91, Cd2+:1.69). Regeneration and leaching test were also conducted for the practical application. After seven regeneration cycles, adsorption efficiency was retained approximately 80%, but removal efficiency was gradually decreased to 55% after fifteen cycles due to the insufficient desorption of loaded heavy metal on the MD and adsorbent loss in the acidic condition during desorption process. Alumina coating on the surface of magnetic core significantly enhanced their tolerance and as a result, the alumina-coated MD exhibited much higher stability and durability than MD even in the harsh acidic condition.