Browsing by Author "B.V. Apparao"

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Adsorption of ethylene glycol and its higher homologues at the mercury/aqueous solution interface
(1979) B.V. Apparao; M.V. Ramanamurti
Adsorption of ethylene glycol, propan-1,2-diol and butan-1,4-diol at the Hg/0.10 mol kg-1 KCl (aq.) solution interface evaluated through equilibrium double layer capacity measurements indicated congruency of adsorption isotherms with respect to both electrode charge (σM) and potential (E); applicability of Langmuir's adsorption isotherm; quadratic dependence of ΔḠo on E and single stable orientation with the hydrocarbon chain facing the electrode and functional group in solution throughout the coverage region for all these compounds. Surface excess, standard free energy of adsorption and the anodic shift of Epzc are in the order: ethylene glycol < propan-1,2-diol < butan-1,4-diol. The shift of charge corresponding to maximum adsorption towards less negative charges in passing from ethylene glycol to butan-1,4-diol has been explained with the help of an equation given by Damaskin and Frumkin.
Specific adsorption of acetate ions at the mercury-lithium acetate (AQ) interface
(1978) M.V. Ramanamurti; B.V. Apparao
Specific adsorption of acetate ions at the mercury-lithium acetate (aq) interface has been investigated using both differential capacity and electrocapillary measurements. Variation of charge due to surface excess of lithium ions (q+) and of charge due to specifically adsorbed acetate ions (q-1 with electrode charge (qM) have been discussed. Such discussion inferred superequivalent adsorption of acetate ions at all positive charges for concentrations of lithium acetate ≥0.20 M whereas Esin-Markov plots predicted the absence of specific adsorption; the prediction of Esin-Markov plots has been shown to be faulty under certain conditions. The plots of φM-2vs q-1 at constant qM for acetate ion resembled the corresponding plots for F- and BF-4 ions; the slope of these plots is negative up to coverages corresponding to 0.20 M lithium acetate. The identification of the isotherm parameter, (∂φM-2/∂q-1)q with the reciprocal of inner layer capacity at constant charge (-1Ci) has been questioned. © 1978.