The present invention relates to an adsorbent material made from the radiation induced graft polymerization of vinylic monomers on a poly-olefinic base material which can be further modified to contain metal adsorbing functional groups. Among the imparted functional groups, the ethylenediamine (EDA) modified and grafted adsorbent showed the highest percentage adsorption ranging from 70% – 99.5% after testing in 1 – 100 ppm Cr(III) solutions. The bound Cr(III) ions were easily stripped off from the adsorbent by a hydrochloric acid solution, achieving 80% percentage desorption. This demonstrates adsorbent reusability, an important merit for materials in this field of application. The adsorbent showed very high selectivity towards Cr(III) even in the presence of Na, Mg and Fe ions. This material can be used for the removal of heavy metals dissolved in liquids, such as in wastewater treatment. The present invention, more specifically, is used for the purpose of removing trivalent chromium from industrial wastewater, particularly from tanning wastewater effluents.