Porous expanded vermiculite containing intercalated cetyltrimethylammonium: a versatile sorbent for the hormone ethinylestradiol from aqueous medium

In this work, a sorbent was developed based on vermiculite intercalated with cetyltrimethylammonium ions to remove the hazardous hormone molecule ethinylestradiol (EE) from the aqueous medium was developed. Characterization by infrared spectroscopy, X-ray diffraction, elemental and thermal analyses, scanning and transmission electron microscopies, N 2 adsorption–desorption and fluorescence showed that vermiculite can be intercalated with 16–19 wt% of cetyltrimethylammonium ions leading to an increase in the d 001 space from 1.15 nm for the pure vermiculite to 1.22–1.24 nm. Sorption experiments with ethinylestradiol taking into account, contact time, pH, initial concentration and amount of adsorbent showed high ethinylestradiol sorption capacities in the range 6.5–9.3 mg EE g −1 . These materials containing the hormone can be regenerated by simple solvent extraction which allowed the recovery and reuse of the adsorbent for at least five times. The obtained results suggest that hydrophobic cavities formed by the C 18 chains of the cetyltrimethylammonium molecules in the vermiculite interlayer space are responsible for the sorption of the ethinylestradiol molecules.