Operational parameters affecting the atrazine removal from water by using cyclodextrin based polymers as efficient adsorbents for cleaner technologies

In this work, the adsorption of atrazine, as emerging pollutant, from water, by using alpha-, beta- and gamma-cyclodextrin-epichlorohydrin water-insoluble copolymers, is presented and carefully investigated by using several complementary techniques. Various in batch experiments were performed, changing different parameters. The aqueous atrazine concentration were evaluated by HPLC analyses, and very interesting results were obtained when alpha-cyclodextrin-based polymer was employed. The presence of weak interactions, not affected by pH changes, involving H-bonds, van der Waals forces, with the possible formation of inclusions complexes host-guest-like between atrazine and the polymers were suggested and confirmed by FTIR-ATR spectroscopy and DSC analysis. Accordingly, the Freundlich isotherm well fitted the experimental data indicating the heterogeneous character of the adsorption process, better described by the pseudo-second order kinetic model. Overall, the thermodynamic analysis showed that the atrazine adsorption on alpha-, beta- and gamma-cyclodextrin-epichlorohydrin polymers was exothermic, exergonic occurring with an increase of entropy. Atrazine desorption experiments were carried out on alpha-EPI polymer through extraction with water, ethanol and methanol, indicating this latter as the most effective solvent for the purpose. Furthermore it was found that CD-EPI polymers can be effectively regenerated and reused at least for five times, thus promoting a circular economy. (C) 2019 Published by Elsevier B.V.