An Imidazole Thione-Modified Polyhedral Oligomeric Silsesquioxane for Selective Detection and Adsorptive Recovery of Au(III) from Aqueous Solutions

Developing a material toward simultaneous detection and recovery of gold ions (Au­(III)) is highly desirable for the economy and the environment. Herein, we report a highly efficient dual-function material for simultaneous Au­(III) detection and recovery by simply introducing abundant imidazole thione and thioether groups in one system. This material, that is, an imidazole thione-modified polyhedral oligomeric silsesquioxane (POSS-2), was prepared by a mild reaction of an imidazolium-containing POSS and sulfur at ambient temperature. The POSS-2 suspension in water can rapidly and selectively detect Au­(III) with a very low limit of detection of 1.2 ppb by fluorescence quenching or a visualized color change from white to dark orange. POSS-2 can also selectively and efficiently capture Au­(III) with a maximum adsorption uptake of 1486.5 mg/g. The adsorption process well fits with the pseudo-second-order kinetic and Langmuir models. The intriguing dual-function performance is better than most of the previous Au­(III) probes or adsorbents. The mechanism study reveals that the detection and adsorption behavior are mainly caused by the redox reaction and coordination between imidazole thione and thioether groups and Au­(III). Furthermore, POSS-2 was successfully utilized to extract gold without interference from a discard CPU. These results indicate the potential application of the present dual-function material for Au­(III) detection and recovery from aqueous solutions. More dual-functional materials could be designed and prepared by this simple strategy.