Poly(sodium acrylate) hydrogels as potential pH-sensitive sorbents for the removal of model organic and inorganic pollutants from water

Abstract

Anionic poly(sodium acrylate), PANa, hydrogels bearing negatively charged -COO -groups were used as sorbents for the removal of colored organic or inorganic model pollutants, namely Crystal Violet and Cu 2+, from water. It was found that PANa hydrogels adsorb stronger Cu 2+ ions than Crystal Violet, as a consequence of the formation of coordination complexes between the hydrogel and the metal ions, while just electrostatic interactions are the major driving forces for Crystal Violet. Furthermore, the influence of pH, i.e. the neutralization degree i of the hydrogel, on its adsorption efficiency was investigated. It is shown that the adsorption of Cu 2+ ions follows stoichiometry, namely one metal ion per two carboxylate anions. On the contrary, the adsorption of Crystal Violet is much lower than the charged stoichiometry.