Sorption Properties of Specific Polymeric Microspheres towards Desethyl-Terbuthylazine and 2-Hydroxy-Terbuthylazine: Batch and Column Studies

This work investigates the sorption properties of poly(divinylbenzene) modified in the Diels–Alder reaction towards persistent and mobile metabolites of terbuthylazine. The batch experiments were carried out to examine the efficiency of desethyl-terbuthylazine and 2-hydroxy-terbuthylazine adsorption on the specific adsorbent and the impact of different factors on the adsorption process. Results fit well to a pseudo-second order kinetic model. It was confirmed that hydrogen bonds play an important role in the studied systems. Five times greater sorption of 2-hydroxy-terbuthylazine than desethyl-terbuthylazine was observed. The molecular structures of both metabolites exhibit complementarity to the arrangement of functional groups in the polymer but the differences in the physicochemical properties of the desethyl derivative make it a highly mobile compound with higher affinity to the aqueous phase. The equilibrium data in the batch study fit the Freundlich isotherm for 2-hydroxy-terbuthylazine, and for desethyl-terbuthylazine the Temkin and Dubinin–Radushkevich models were better. The adsorption capacities obtained under dynamic conditions were comparable with batch results. For column adsorption modeling the Bohart–Adams, Wolborska, Thomas and Yoon–Nelson models were used. The proposed microspheres can be reused easily with no significant decrease in adsorption capacity by using ethanol as eluent in the desorption.