TITLE:
Sorption of Denatonium to Kaolinite Clay from Water
AUTHORS:
Garry S. Crosson, Stephanie Thorpe, Yun-Yun Zhou, James Dawson
KEYWORDS:
Denatonium; Sorption Isotherms; Kaolinite; Clay Minerals; Water Quality
JOURNAL NAME:
Journal of Environmental Protection,
Vol.4 No.9,
August
28,
2013
ABSTRACT: Denatonium
benzoate is an aversive agent proposed for use in certain anti-freeze
formulations to reduce poisoning events of pets and humans. Unfortunately, the
sorption properties of denatonium cations to soil and/or soil components have
not been investigated. In this paper, denatonium sorption to reference
kaolinite clay under varied pH, ionic strength, and cation identity is described. The data clearly indicate that the nature of the background electrolyte cation modulates denatonium sorption
with enhanced sorption occurring the presence of potassium ions versus minimal
sorption occurring in a calcium chloride electrolyte at each pH studied as
estimated using Dubinin-Raduskevich (D-R) isotherms. The effect of background
electrolyte concentration on sorption was consistent with an ion-exchange
process wherein the sorption capacity increased with decreased background
electrolyte concentration. An interesting and unexpected observation of
increased sorption capacity (estimated using the D-R model) with decreasing pH
was observed in 10 mM CaCl2 in contrast to an observed and expected increase in denatonium sorption to
kaolinite in the presence of either of 10 mM NaCl or 10 mM KCl. Estimates of
the mean sorption energy using D-R isotherms ranging from 2.65 kJ/mol in 10 mM CaCl2 at pH 4 to 4.68 kJ/mol at pH 10 suggesting that the sorption process is not exclusively ion-exchange.