Multiple-Acid Equilibria in Adsorption of Carboxylic Acids from Dilute Aqueous Solution

Abstract

Equilibria were measured for adsorption of carboxylic acids from aqueous, binary-acid mixtures of lactic and succinic acids and acetic and formic acids onto basic polymeric sorbents. The experimentally determined adsorption isotherms compared well with model predictions, confirming that simple extensions from adsorption of individual acids apply. Fixed-bed studies were carried out that establish the efficacy of chromatographic fractionation of lactic and succinic acids using basic polymeric sorbents. Finally, sequential thermal and solvent regeneration of lactic and acetic acid-laden sorbents was investigated as a method to fractionate among coadsorbed volatile and nonvolatile acids. Essentially complete removal of the acetic acid from the acid-laden sorbent was achieved by vaporization under the conditions used; a small amount of loss of lactic acid (about 11%) was observed.

Investigating the differences in acid separation behaviour on weak base ion exchange resins

“…The results, here, indicate possibility of incomplete dissociation of the resin salt. The sorption capacity of this resin above this concentration level was higher than the theoretical capacity of the resin, similar to the observations made by Husson and King (1999a) and, hence, no further evaluation was possible using the present treatment.…”

“…Figs. 6 and 7 compare the equilibrium data of this work (indicated by bold lines) and also using similar data from some of the earlier works (Kunin, 1958;Adams et al, 1969;Bhandari et al, 1992Bhandari et al, , 1996Takatsuji & Yoshida, 1997;Husson & King, 1999a). In contrast to the earlier reports on the individual sorption equilibrium curves and isolated treatment of the same, it is now possible for us to have a clearer picture of sorption behaviour on di!erent weak base resins.…”

“…Husson and King (1999a) attributed it to higher level of adsorption as against monolayer sorption and then correlated the sorption data using modi"ed Langmuir isotherm equation. The theoretical treatment of this work has potential to explain higher values of sorption on the basis of double layer.…”

“…In many instances, acid sorption was considered irreversible and the sorption equilibrium was interpreted in terms of simple Langmuir-or Freundlich-type isotherm. The application of Langmuir-or Freundlich-type isotherm was, however, not found satisfactory in some cases (Husson & King, 1999a) and anomalous nature of sorption equilibria was also indicated with polybasic acids (Bhandari et al, 1997). The experimental and theoretical information on acid sorption is largely incomplete due to the following: 1.…”

Exchange characteristics of monocarboxylic acids and monosulfonic acids onto anion-exchange resins

“…However, there are few fundamental researches on adsorption of organic compounds by anionexchange resins [9][10][11][12][13]; the information on the adsorption characteristics of organic acids onto anion-exchange resins is not sufficient.…”