Extraction of sulfuric acid with tri-n-laurylamine in benzene

Analyses of the organic phase showed that in the extraction of sulfuric acid in concentrations csub(H2SO4)sup(0)<=0.5csub(A), hydrated normal amine sulfate is formed as a monomer. The hydration number depends on the concentration of the sulfate in the organic phase (for csub(A)=0.5-0.1 mole/l, c'sub(H2O)=3-0.4). The mean degree of association of normal amine sulfate is practically independent of the concentration of water in the organic phase. During the conversion of normal amine sulfate to hydrosulfate, water is displaced from the molecule of the normal sulfate and the sulfuric acid is bound to the freed bonds. When csub(H2SO4)sup(0)=2csub(A), only amine hydrosulfate hydrated with one molecule exists in the organic phase as dimer. The degree of association depends on the activity of water in the system. For asub(w)→0 the hydrated dimer is converted to an anhydrous trimer. During the study of the effect of alcohol on the extraction of sulfuric acid with TLA, normal amine sulfate was found to be solvated by two molecules of alcohol, hydrosulfate by one molecule. The solvation of the SO42- group affects the formation of amine hydrosulfate. The hydrosulfate is formed at higher csub(H2SO4)sup(0) concentrations. The structure of the organic phase was suggested, based on all the data obtained and on previous results. Six-membered rings composed of the links AH+, HSO4-, and H2O or of the links AH+ and HSO4- only are formed in the organic phase, depending on whether higher or lower activities of water occur in the system. (author)