Extraction Equilibria of Hydrochloric Acid by Trioctylamine in Low-Polar Organic Solvents

Abstract

Two-phase emf titrations have been performed for the extraction of hydrochloric acid from aqueous solution containing 1 M NaCl (M=mol dm−3) by trioctylamine (TOA) dissolved in cyclohexane, toluene, benzene, chlorobenzene, nitrobenzene, cyclohexane–benzene mixtures, and benzene–nitrobenzene mixtures. It has been found that the extraction is accompanied with the formation of monomeric trioctylammonium chloride and its successive aggregation from dimer to micell (n-mer) in organic phase: ‾TOA+H++Cl−=‾TOAHCl, Kd; (‾TOAHCl)i−1+‾TOAHCl=(‾TOAHCl)i, \barKi(i=2,3,···,n), where the concentration quotients of successive aggregation, \barKi, satisfy the relation 2 \barK2=3\barK3⁄2=···=n\barKn⁄(n−1). The quotients Kd and \barK2 vary with the total volume fraction of TOA in organic phase, ΨR°, according to equations, In Kd=1nKd°+gΨR° and 1n \barK2=1n\barK2°+h\barΨR°. Diluent effect on the equilibrium constants Kd° and \barK2° are discussed in detail based on the theory of regular solution.

Separation of Protocatechuic Acid Using Di-(2-ethylhexyl)phosphoric Acid in Isobutyl Acetate, Toluene, and Petroleum Ether

“…The average extraction efficiency is approximately 58.84% in IBA, 12.29% in toluene, and 10.86% in petroleum ether. Thus, the distribution coefficient was found to be increased with the acid concentration, which may be due to the higher driving force to accommodate the acid in the organic phase, and also may be due to the emaciation of the bond between the acid and water molecules as acid molecules become more available in the aqueous phase …”

“…Thus, the distribution coefficient was found to be increased with the acid concentration, which may be due to the higher driving force to accommodate the acid in the organic phase, and also may be due to the emaciation of the bond between the acid and water molecules as acid molecules become more available in the aqueous phase. 63 The two main factors affecting the extractability of the carboxylic acid in physical extraction are the extent of hydration of the acid and the energy of the bond to the water molecule. 64,65 The probable reason for the low values of distribution coefficients (<1) and extraction efficiency may be due to the higher affinity of PCA for water than diluents, which makes it difficult to separate.…”

Effect of temperature on equilibria for physical and reactive extraction of protocatechuic acid

“…With an increase in PCA concentration from 0.001 to 0.01 kmol m À3 E % (extraction efficiency) was found to improve, with the highest E% obtained at 0.01 kmol m À3 of PCA. This behavior can be attributed to the increase in driving force to house PCA in the organic phase and also the emaciation of the bond amongst water molecules and acid molecules due to the more accessibility of molecules of PCA in aqueous phase [51].…”

Coupled reaction and solvent extraction process to form Li2CO3: Mechanism and product characterization

“…N235 is a typical industrial mixed reagent for trioctyl amine (TOA). Both TOA and N235 are typical extractants for HCl recovery from waste water . Isooctanol is a typical polar organic reagent, which is always used as diluent.…”