Liquid – Liquid Extraction of Hydrochloric Acid from Aqueous Solutions by Tri-n-dodecylamine and Tri-n-octylamine / diluents

Abstract

The extraction of HCl from aqueous solutions using two types of long-chain tertiary amines tri-n- dodecylamine/ kerosene and tri-n-octylamine/ kerosene in the presence of octanol-1 or tributyl phosphate as modifier has been studied. The effect of mixing time, HCl concentration in the aqueous phase, amine concentration, organic to aqueous phase ratio, modifier percentage in the organic phase, NaCl concentration in the aqueous phase and temperature were studied. The effect of some diluents such as: toluene, benzene and xylene on HCl extraction was also investigated and found to follow the order:
Benzene > toluene > kerosene + 10% octanol-1 ≈ xylene
Tri-n-dodecylamine and tri-n-octylamine showed a great affinity towards HCl in all tested diluents. Both amines (TDA and TOA) can be successfully used for HCl recovery from aqueous acidic solutions.
Water was found to be effective to strip HCl from the acid loaded organic phase and more than 95% of HCl can be recovered in three stripping stages at Vaq/Vorg = 20/1 and 75 °C.