Selective adsorption of silver(I) by dimercaptosuccinic acid (DMSA) functionalized polyhedral oligomeric silsesquioxane (POSS)-based hybrid polymer: Behavior and mechanism

Effective and selective recovery of precious metal silver (Ag(I)) from wastewater can promote resource recycling and mitigate environmental pollution. In this study, dimercaptosuccinic acid (DMSA) functionalized polyhedral oligomeric silsesquioxane (POSS)-based hybrid polymer (DPHP) was synthesized and employed for the adsorption of Ag(I) from aqueous solution. The obtained adsorbent was characterized using SEM-EDS, XPS, solid-state 13 C NMR, and 29 Si NMR spectra. Batch adsorption experiments were conducted to evaluate the adsorption performance of DPHP for Ag(I). The results revealed that the maximum adsorption capacity of DPHP for Ag(I) was 494.65 mg g −1 at pH 4, and the adsorption process could be well described by pseudo-second-order and Sips models. Thermodynamic studies implied the adsorption of Ag(I) was an endothermic and spontaneous adsorption process in nature. Adsorption and desorption experiments demonstrated that the regeneration efficiency of DPHP remained above 83 % after five cycles and the preconcentration factor of DPHP was determined to be 125. Furthermore, DPHP exhibited selectivity to Ag(I) in solutions containing a variety of competitive metal ions and simulated industrial wastewater. Based on density functional theory (DFT) calculations, as well as XPS, FTIR, and Raman analyses, the interaction between Ag(I) and DPHP involved electrostatic attraction, ion exchange, and coordination, with the coordination mainly between thioether and carboxy groups and Ag(I) ions. Overall, DPHP is a promising adsorbent for the recovery of Ag(I) from aqueous solutions.