Ammonium adsorption from synthetic and real mining wastewaters by eight-clay based adsorbents

The main purpose of this study was to examine commercial clay-based adsorbents without modifications for ammonium adsorption and compare their ability to reduce the amount of ammonium from a liquid phase. For the first time, to our knowledge, bentonite, chabazite, clinoptilolite, and phillipsite were tested for ammonium adsorption in the same study. The comparison of the materials was conducted in both simulated and real wastewaters to obtain reliable information about their performance in real conditions. It was found that all the adsorbents possessed ammonium removal capacity, but the amount reduced depended on the pH and other cations present in the examined liquid. Experimental isotherms were compared with the Langmuir, Freundlich, and Sips isotherms. Among these three isotherm models, the best fit was found with the Sips model in all of the cases. It was also observed that zeolite from Sigma–Aldrich had the best maximum ammonium adsorption capacity of the examined adsorbents. All in all, in different conditions, the zeolite and the two chabazites were the best ones to adsorb ammonium.