Extraction and separation of Pd(ii)/Pt(iv) by neutral sulfur-containing extractant from hydrochloric acid medium

Recycling platinum group metals from secondary resources has always been a difficult task in research. In this work, the extraction and separation of Pd(ii)/Pt(iv) by the application of 2-mercaptobenzimidazole from hydrochloric acid medium was investigated. At first, the effects of the experimental conditions were studied to optimize the parameters of extraction and separation, such as time, acidity, salinity and extractant concentration. Then, the extraction mechanisms of Pd(ii)/Pt(iv) were confirmed by UV-vis, FT-IR and electrostatic potential (ESP) map analysis. Moreover, through the screening of various stripping agents, a feasible strategy to separate Pd(ii)/Pt (iv) was proposed. Subsequently, 92.1% Pd(ii) and 98.7% Pt(iv) were successfully obtained by two-stage extraction and Pd(ii)/Pt(iv) were separated from the loaded organic phase using thiourea as the stripping agent. Finally, 2-mercaptobenzimidazole also showed excellent selectivity for recovering individual Pd(ii)/Pt(iv) from multi-metal solutions.