Adsorption separation of Ni(II) ions by dialdehyde o-phenylenediamine starch from aqueous solution

Removal of nickel(II) ions from aqueous solution by using dialdehyde o-phenylenediamine starch (DASPDA) was investigated. The DASPDA was prepared from a reaction between dialdehyde starch (DAS) and o-phenylenediamine, and characterized by element analysis, FT-IR spectra and SEM. The FT-IR, results showed that DASPDA has different functional groups compared with DAS and these functional groups are able to react with metal ion in aqueous solution. Batch adsorption experiments were conducted to study the main parameters such as adsorption time, pH, initial Ni(II) ion concentrations and temperature. The adsorption results revealed that the optimal pH was 5.0, the equilibrium time was about 120 min, and the adsorption capacity increased with the increase of substitution DS (0.33, 0.49 and 0.90) of the DASPDA. Moreover, the Freundlich adsorption isotherm gave a satisfactory fit of the equilibrium, and the adsorption process is endothermic. The chelating of Ni(II) ions to DASPDA by adsorption is enhanced as the temperature increases.