Abstract: The adsorption of quinoline by Na+- and Ca2+-montmorillonite, illite, and kaolinite in water suspensions was studied for varying physico-chemical conditions. The shapes of the adsorption isotherms depended upon these imposed environmental conditions, which were quinoline concentration, pH, salinity, time, and temperature.
In order to be in the range of concentrations of organic materials in natural waters, these studies covered the concentration range, from 0 to several hundred ppm. Of the variables studied, pH was critical. Throughout the pH range 8.5–6.0, adsorption increased as pH decreased. The change in adsorption as salinity increased depended on pit, clay mineral, and quinoline concentration. In our experiments, samples reached equilibrium within 2–3 hr, and moderate temperature changes made little difference in adsorption amounts.
Under the same conditions, Na+-montmorillonite adsorbed the most quinoline, kaolinite the least, and Ca2+-montmorillonite and illite intermediate amounts.
Two mechanisms seem to control this adsorption : ion exchange and molecular adsorption. This paper attempts to explain the effects of the physico-chemical environment on adsorption by these two mechanisms.