Adsorption of copper–citrate complexes on chitosan: Equilibrium modeling

The effects of complexes on the adsorption of copper from citrate solutions using chitosan were investigated. Various copper to citrate ratios and solution pHs were used to determine the copper adsorption capacity on the chitosan and a mathematical model was developed to simulate the copper adsorption process. According to the model, the three parameters influencing the copper adsorption capacity are the fraction of protonated amine groups (RNH3+), the fraction of anionic copper–citrate complexes (CuL− and CuL24-), and the fraction of anionic citrate complexes (HL2−, H2L−, and L3−). The copper adsorption capacities onto chitosan at varying copper–citrate ratios and solution pHs can be predicted by the mathematical model. With such a model to facilitate understand the copper adsorption mechanisms at varying copper–citrate ratios and solution pHs, the copper adsorption efficiency can be increased by the adjustment of the copper–citrate ratio and solution pH.