Studies of two-phase equilibria by liquid-liquid segmented flow extraction of dithiocarbamic acids into various solvents.
A method for the study of two-phase equilibria by extraction in liquid-liquid segmented flow is presented. The main advantage of the method is the very rapid equilibration achieved. In many cases a contact time of 5 sec is sufficient. By performing the measurements needed on-line with the extraction the total residence time of a substance studied in the system can be kept below 10 sec. This makes it possible to study two-phase equilibria of moderately unstable compounds. Other advantages are the semi-enclosed design, which minimizes contact with solvent fumes and increases the speed of operation after the system has been set up. The system has been used for a study of the two-phase equilibria of dithiocarbamic acids. The dithiocarbamates are often used for the separation and preconcentration of metals, and co-extraction of the reagent can cause severe interference in the final determination. By means of the extraction constants presented, the extraction of diethyldithiocarbamic acid and pyrrolidine-dithiocarbamic acid into Freon 113, carbon tetrachloride, methyl isobutyl ketone and chloroform can be estimated.
Bäckström
K
K
Department of Analytical Chemistry, The Royal Institute of Technology, S-100 44 Stockholm, Sweden.
Danielsson
L G
LG
Ingman
F
F
Huazhang
Z
Z