Elastomeric nanocomposite foams for the removal of heavy metal ions from water

We report the fabrication and utilization of elastomeric polymer nanocomposite foams for the efficient removal of Pb²⁺ and Hg²⁺ heavy metal ions from polluted water. The polydimethylsiloxane (PDMS) foams are properly modified in order to become hydrophilic and allow the polluted water to penetrate in their volume. The ZnSe colloidal nanocrystals (NCs) that decorate the surface of the foams, act as active components able to entrap the metal ions. In this way, after the dipping of the nanocomposite foams in water polluted with Pb²⁺ or Hg²⁺, a cation exchange reaction takes place, and the heavy metal ions are successfully removed. The removal capacity for the Pb²⁺ ions exceeds 98% and the removal of Hg²⁺ ions approaches almost 100% in the studied concentrations region of 20-40 ppm. The reaction is concluded after 24 h, but it should be noticed that after the first hour, more than 95% of both the metal ions is removed. The color of the foams changes upon heavy metal ions entrapment, providing thus the opportunity of an easy detection of the presence of the ions in water. Taking into account that the fabricated foams provide good elastic properties and resistance to heat, they can be used in different conditions of water remediation.