Abstract
A cyclodextrin-based polymer was prepared by crosslinking β-cyclodextrin with epichlorohydrin to be assessed as a sorbent material for cresols in packed-bed columns. Both Langmuir and Freundlich isotherms were appropriate to describe the sorption equilibrium in the conditions tested, and the thermodynamic parameters obtained for this process confirmed its exothermic nature with similar enthalpies (between − 6.8 and − 8.3 kJ/mol) for the three isomers. The removal of cresols from water was carried out in nine cycles of sorption–desorption in fixed-column experiments with the cyclodextrin hydrogel, achieving sorption capacities of 6.2, 11.6, and 15.1 mg/g for o-, m-, p-cresol, respectively. These differences in sorption capacities are due to the different chemical structures of cresols, that is, the relative position of the methyl and hydroxyl groups. However, similar sorption rates were observed for each isomer, with a mean value of 0.10 mg-cresol g-CDP–1 min–1 in all cases. The experimental data for the breakthrough and the elution curves have been successfully modeled by two effective two-parameter equations, a dose–response model for the sorption step and a pulse-peak model for the regeneration step. The cyclodextrin polymer matrix has been proven to be an effective a good sorbent material for removing cresols from water, exhibiting remarkable reusability performance and structural stability throughout the successive elution steps carried out with methanol.
Highlights
Adsorption is a mass transfer operation, included among the advanced treatment technologies, applied to wastewater treatment and water purification usually to remove refractory pollutants
The sorption of cresol isomers in packed beds composed of hydrogel beads of a cyclodextrin-based polymer and their regeneration have been studied for nine operating cycles
No substantial differences were observed in the sorption rates for each isomer, giving a mean value of about 0.10 mg-cresol g-cyclodextrin-based polymers (CDPs)–1 min–1 in all systems
Summary
Adsorption is a mass transfer operation, included among the advanced (or tertiary) treatment technologies, applied to wastewater treatment and water purification usually to remove refractory pollutants. Cyclodextrin-based hydrogels are synthetic polymeric adsorbents that have been extensively tested for this purpose [2,3,4]. Journal of Polymers and the Environment (2022) 30:1189–1198 coconut charcoal, might show a better adsorption performance, this investigation demonstrates that these hydrogel sorbents are stable through successive sorption–desorption cycles. The present work addresses the performance of a CDP applied for the removal of cresols from water in several cycles of sorption–desorption in fixed-column experiments. Cresols are extensively used as organic reagents in different manufacturing industries, and their discharge to the aquatic environment is a matter of concern [11]. The sorption equilibrium data of o-, m- and p-cresol on the CDP have been fitted to the Freundlich and Langmuir isotherm models and the thermodynamic parameters of these processes have been calculated
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