A survey of multi-component sorption models for the competitive removal of heavy metal ions using bush mango and flamboyant biomasses

Abstract

This manuscript reports the sorption of Cd2+, Pb2+ and Ni2+ ions in binary mixtures using raw and acid-treated flamboyant and bush mango biomasses. Surface chemistry of these biomasses was tailored for heavy metal sorption using a tartaric acid treatment. Sorption studies showed that Pb2+ caused a strong antagonistic effect on the removal of Cd2+ and Ni2+ in binary mixtures using both raw and acid-treated sorbents where the electrostatic interactions may play an important role in heavy metal removal. XPS and FTIR characterization results confirmed the role of acid functional groups of bush mango and flamboyant biomasses in the single and multi-component removal of heavy metal ions. On the other hand, capabilities and limitations of a set of multi-component isotherm equations were analyzed in the modeling of the competitive sorption behavior of these sorbents. These isotherms included the non-modified, modified and extended version of Langmuir, Sips and Redlich-Peterson equations and the Sheindorf-Rebhun-Sheintuch and IAST – Sips models for multi-component systems. Results showed that the modeling of the competitive sorption of Cd2+, Pb2+ and Ni2+ on these lignocellulosic sorbents is challenging with tested isotherms. However, the multi-component Sips equation obtained from IAST was the most effective isotherm for modeling this antagonistic heavy metal sorption. This isotherm model is promising for process design and optimization of water treatment strategies for the multi-component removal of heavy metal ions using these and other lignocellulosic biomasses.