Optimization of the Supercritical Fluid Extraction of Primary Aromatic Amines

Abstract
A systematic evaluation of the parameters affecting the supercritical fluid extraction (SFE) of the following primary aromatic amines was performed: 1,4-phenylenediamine, 2,4-diaminotoluene, benzidine, 4,4″-methylenebis(2-chloroaniline), 3,3″-dimethylbenzidine, and 3,3-dichlorobenzidine. Nitrous oxide was utilized as the supercritical fluid, along with six different chemical modifiers. The effect of modifier concentration was examined, as were the effects of pressure, extraction temperature, time, and volume. 1,6-Hexanediamine in methanol was demonstrated to be an effective SFE modifier. The extraction was optimized with a modifier concentration of 5% in methanol, a pressure of 350 atm, three extraction volumes, and two modifier addition cycles.