Chelating resins have been considered to be suitable materials for the recovery of heavy metals in water treatments. A chelating resin based on modified poly(styrene-alt-maleic anhydride) with Melamine was synthesized. This modified resin was further reacted with 1,2-diaminoethan in the presence of ultrasonic irradiation for the preparation of a tridimensional chelating resin on the nanoscale for the recovery of heavy metals from aqueous solutions. The adsorption behavior cobalt (II) ions was investigated by the synthesis of chelating resins at various pH’s. The prepared resins showed a good tendency for removing the cobalt (II) ions from aqueous solution, even at acidic pH. The resin was characterized by Fourier transform infrared spectroscopy, scanning electron microscopy, X-ray diffraction analysis.The adsorption process of cobalt (II) on SMA, SMA-M and SMA-M- E were tested with Langmuir isotherm model and the isotherm constants were deduced from this.