Adsorption of cadmium ions on thiol or sulfonic-functionalized poly(dimethylsiloxane) networks

• Thiol/sulfonic poly(dimethylsiloxane) network was obtained by a simple methodology.
• Cd (II) was absorbed efficiently from ethanol and/or water solution on the networks.
• Langmuir/Freundlich model describes adsorption in ethanol/water, respectively.
• Modified sulfonic-PDMS material was able to interact with water efficiently.

Thiol or sulfonic-functionalized poly(dimethylsiloxane) elastomeric networks were prepared from 3-mercaptopropyltrimethoxysilane or the oxidized silane. The characterization of these materials using infrared spectroscopy (IR) and 13C/29Si nuclear magnetic resonance (NMR) suggested that the materials were functionalized with the aforementioned groups and that the networks are composed of linear segments of PDMS crosslinked by nodes of silsesquioxanes, which contain T3 and/or T2 type silicon. The thermogravimetric analysis of the polymeric networks revealed that they exhibit good thermal stability. The adsorption capacities for cadmium ions in ethanolic solutions were 0.33 and 0.89 mmol g−1 for the thiol- and sulfonic-functionalized PDMS networks, respectively. In water solution the material with thiol group do not adsorbed Cd (II), however, the network with sulfonic group adsorbed 0.70 mmol g−1. In ethanol, the linearization of the adsorption isotherms revealed that the Langmuir model describes the interaction between the adsorbate–adsorbent, in water, the Freundlich adsorption model described the metal adsorption for the sulfonic-functionalized PDMS.

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