Designed pendant chain covalently bonded to silica gel for cation removal

The precursor 1,4-bis(3-aminopropyl)piperazine organofunctionalized silica gel reacted with methylacrylate to yield a new inorganic–organic chelating material, by adopting a heterogeneous and divergent synthetic approach. The synthesized materials were characterized through elemental analyses and spectroscopic techniques such as infrared, nuclear magnetic nuclei of carbon-13 and silicon-29. Due to the increment of basic centers attached to the pendant chains the metal adsorption capability of the final chelating material, was found to be higher than its precursor. The adsorption of metal ions from aqueous solution followed the order Cu 2+ > Ni 2+ > Co 2+. Both Langmuir and Freundlich models were found to be applicable for the adsorption of copper, with the equilibrium parameter value within zero to one. The competitive sorption behavior, with variation of pH, was favorable for the separation of copper from binary mixtures with nickel and cobalt. When sodium, potassium and magnesium cations are present in the medium little effects on adsorption were observed, thus suggesting that the synthesized material can be useful for removal of toxic/heavy metal ions from natural and wastewater systems.