Extraction p-Aminobenzene Sulfonic Acid from Dilute Solution by Chemical Complexation with Aliquat 336

Based on systematic investigation and analysis of literature, p-aminobenzene sulfonic acid is selected as a typical amphoteric organics to be separated from dilute solution. A chlorinated quaternary ammonium salt, Aliquat 336, is used as complexing agent. Since the pH of aqueous solution is an important factor in chemical complexation extraction of the solutes, its effect on extraction equilibrium is especially studied in the experiments. The effects of type of diluents, concentration of complexing agent and salt on distribution ratio D are also investigated. By using Mass Action Law, an expression of equilibrium distribution ratio for p-aminobenzene sulfonic acid/ Aliquat 336/ diluent system is proposed. The results show that the precision of the model parameters fitting are quite satisfactory. Distribution ratio D is higher in inert diluent and the sequence is benzene tetrachloromethane chloroform n-octanol. The existence of salt can reduce D rapidly. Meanwhile, the extraction behavior by Aliquat 336 was compared with that by Alamine 336, and there was a wider efficient pH region for Aliquat 336.