Abstract
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.
Highlights
Herbicides, as well as their degradation products, are toxic substances that can remain for many years in various environmental compartments due to their high chemical and biochemical stability in the environment
For 2-hydroxy-terbuthylazine, which is even much better adsorbed than its parent compound, the intensity of adsorption obtained under acidic conditions was considerably smaller; such results can still be considered satisfactory
The results of this study show that hydrogen bonds have a significant impact on sorption efficiency
Summary
Herbicides, as well as their degradation products, are toxic substances that can remain for many years in various environmental compartments due to their high chemical and biochemical stability in the environment. Terbuthylazine metabolites as persistent and mobile chemicals are frequently detected in the environmental compartments in Europe, in many cases at concentrations higher than the European drinking water limit according to Directive (EU) 2020/2184 [23] equal to 0.1 μg L−1, e.g., in the range of up to 9.24 μg L−1 in surface waters for 2-hydroxyterbuthylazine and 2.90 μg L−1 and 3.50 μg L−1 for desethyl-terbuthylazine in surface water and groundwater, respectively [24,25,26,27]. A substantial analytical challenge exists related to the detection and quantification of persistent and mobile chemicals in the environmental samples It is very important, especially for those substances that have not previously been covered in the routine monitoring, which include desethyl-terbuthylazine and 2-hydroxy-terbuthylazine. The aim of this study is to examine the kinetics and mechanism of terbuthylazine metabolites adsorption in the proposed adsorbate–adsorbent systems
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