Abstract
The cation binding behavior of arabate was investigated by conductivity measurements with reference to the various colligative properties of arabate reported previously. The equivalent conductance of arabic anion, Λp, was found to be about 6 (Ω-1.cm-1.eq-1) from the conductivity titration curves of arabic acid with tetra-n-butylammonium hydroxide (TBA-OH). Using the value of Λp = 6, cation binding of arabate was estimated by the conductivity measurement of TBA-arabate at a constant concentration of 1.2 × 10-2 (eq/kg) in the presence of various added salts, and the binding curves were found to be of Langmuir type. Since the saturated amounts of cation binding, x∞ were observed to be similar to each other among cations of the same valency, since they increased with the valence number of cations, the interactions of arabate with cations were suggested to be due to electrostatic force. The present results are discussed in terms of the estimation methods of cation binding behavior of arabate.
