Evaluation of pumice stone as an alternative low-cost adsorbent for atenolol removal, an emerging contaminant

Atenolol is a β-blocker considered to be an emerging contaminant due to its potential risk to aquatic ecosystems and human health. The removal of atenolol from water was studied using pumice stone, an amorphous, porous, and low-cost adsorbent. The adsorption process was evaluated in ultrapure water by kinetic, pH, and isotherm batch assays; the matrix effect of wastewater and desorption using ultrapure water were evaluated as well. The adsorption of atenolol in pumice stone adjusted to the pseudo-second-order kinetic model showed fast adsorption in the first 2 h and reached final equilibrium after 48 h. The highest removal in ultrapure water was at pH 7.0. The maximum experimental adsorption capacity obtained for ultrapure water and actual wastewater ranged from 0.632 to 0.154 mg/g, respectively. The equilibrium adsorption experiments showed S-shaped isotherms following the Freundlich model and an increase in adsorption capacity as equilibrium concentration increased. Desorption was up to 55%, demonstrating the potential regeneration of the adsorbent, even on site, using ultrapure water. Furthermore, the results for atenolol, a cationic substance (pKa 9.6), suggest the application of negatively charged pumice as an adsorbent for similar substances of concern.