Facile preparation of thioether/hydroxyl functionalized polyhedral oligomeric silsesquioxanes hybrid polymer for ultrahigh selective adsorption of silver(I) ions

It is a difficult task to remove Ag(I) ions selectively from the complex wastewater containing low concentration of silver(I) ions and high concentration of interfering ions. In this work, the polyhedral oligomeric silsesquioxanes (POSS) hybrid polymer (PSDT) functionalized with thioether/hydroxyl groups was facilely synthesized by photo-initiated thiol-ene polymerization of vinylPOSS and 1, 4-dithiothreitol. The PSDT showed ultrahigh selectivity to Ag(I) ions in a wide pH range, which could completely remove trace level of Ag(I) ions (1 mg L −1 ) from the complex wastewater containing concentrated interfering ions such as Pb(II), Cu(II), Ni(II), Zn(II), Ca(II) and Fe(III) ions (each 200 mg L −1 ), nevertheless, those interfering ions were hardly adsorbed on the PSDT polymer. Moreover, the maximum adsorption capacity for Ag(I) by PSDT was 303 mg g −1 at pH 0.5, and the distribution coefficient ( K d ) for Ag(I) ions could reach 1,620,000 mL g −1 , which was significantly greater than most of the adsorbent materials reported. The high sulfur content (5.93 mmol g −1 ) of nanostructured PSDT and the formation of a stable five-membered Ag(I)-chelated ring may be the major causes for the ultrahigh selective adsorption of Ag(I) ions by PSDT.