Extraction and separation of Pd(Ⅱ), Pt(Ⅳ), Fe(Ⅲ), Zn(Ⅱ), Cu(Ⅱ) and Ag(Ⅰ) from hydrochloric acid solutions with selected cyanamides as novel extractants

摘要

Three structurally related novel extractants namely: N,N-dihexylcyanamide (DHCY), N, N-di(2-ethylhexyl)cyanamide (DEHCY) and N,N-di-octylcyanamide (DOCY) were synthesized in our laboratory and characterized by different techniques. The general method for synthesizing these extractants was based on the reaction of relevant secondary amines with cyanogen bromide in presence of sodium acetate anhydride. Their extracting ability in toluene as a diluent for Pd(Ⅱ), Pt(Ⅳ), Fe(Ⅲ), Zn(Ⅱ), Cu(ⅡI) and Ag(Ⅰ) from hydrochloric acid media has been studied. The extraction of hydrochloric acid was studied also. Pd(Ⅱ) was strongly extracted by these extractants at low hydrochloric acid concentrations and the extraction decreased with increasing hydrochloric acid concentration while the reverse was obtained in the extraction of Pt(IV), Fe(III) and Zn(II). Under similar extraction conditions Cu(Ⅱ) and Ag(Ⅰ) were found poorly extracted. Hydrochloric acid was extracted only in its high concentration region. A systematic investigation has been carried out on the extraction of Pd(II) using two of the synthesized extractants. Pd(Ⅱ) was extracted as a solvated complex with the composition, metalxhloride ion:extractant = 1:2:2. The extracted species were studied also using IR spectra.