Models for tetracycline in aquatic environments

The interactions of tetracycline with model clay adsorbents has been studied as a function of suspension pH, ionic strength, and adsorbate concentration. The model clay adsorbents were the Na, Ca, and dodecyltrimethylammonium forms of bentonite and a tannic acid covered bentonite. The adsorption isotherms were of the Langmuir type and the adsorption capacity decreases in the order tannic acid-clay > Ca-clay > Na-clay > dodecyltrimethylammonium-clay. The adsorption onto the clay substrates decreases as the ionic strength and pH increases.