Silver(I) sorption by silica gels chemically modified with mercaptopropyl or dipropyl disulfide groups

Abstract

The sorption of silver(I) from nitric and hydrochloric acid solutions with silica gels chemically modified with mercaptopropyl groups (MPSG) and dipropyl disulfide groups (DDSG) has been studied. For nitric acid solutions, the highest silver(I) recovery factor (99.0–99.9%) is reached in the acidity range between 5 M HNO 3 and pH 8 for MPSG and between 2 M HNO 3 and pH 8 for DDSG. In the sorption of silver(I) from hydrochloric acid solutions with MPSG, the recovery factor is 99% at pH 2–7. The recovery of silver(I) from chloride solutions with DDSG depends significantly on the chloride ion concentration. The treatment of silver-containing DDSG with a water-ethanol or water-dimethylformamide solution of Michler thioketone yields an intensely colored, reddish claret, mixed-ligand silver(I) complex on the sorbent surface. The diffuse reflectance spectrum of this complex shows a band peaking at 520 nm.