Temperature-swing adsorption of precious metal ions onto poly(2-(dimethylamino)ethyl methacrylate) gel

The temperature-swing adsorption (TSA) of heavy metal ions onto 2-(dimethylamino)ethyl methacrylate (DMAEMA) gel has been examined. The DMAEMA gel adsorbs precious metal ions (Pt(IV), Au(III), and Pd(II)) in HCl aqueous media as a result of the electrostatic interactions between the protonated amino groups in the gel and the anionic chloro complexes, while it is inactive against Cu(II) and Ni(II) cations. The amount of Pt(IV) ions adsorbed onto the DMAEMA gel decreases linearly with an increase in temperature. The TSA operation was successfully carried out; the DMAEMA gel repeatedly adsorbed and desorbed Pt(IV) ions in the temperature-swing operation between 20 °C and 60 °C. The TSA technique using the DMAEMA gel is simple, environment-friendly, and potentially applicable in various separation processes for precious metals in industries.