Vermiculite modified with alkylammonium salts: characterization and sorption of ibuprofen and paracetamol

Abstract

In this work, the clay mineral vermiculite (VT) was treated using the bromide form of quaternary alkylammonium salts—ethylhexadecyldimethylammonium (EHDDMAB), hexadecyltrimethylammonium (HDTMAB), tetradecyltrimethylammonium (TDTMAB) and tetrabutylammonium (TBAB), in order to obtain the organo-vermiculites (OVT) named as VT-EHDDMA, VT-HDTMA, VT-TDTMA and VT-TBA, respectively. These sorbents and the precursor VT were characterized using several techniques which allowed to infer the intercalation of the alkylammonium salts in the interlayer space of VT, except VT-TBA, and these materials were evaluated as sorbents for ibuprofen and paracetamol. VT and OVT presented no significant interactions with paracetamol and sorbed less than 10% of the initial concentration. On the other hand, two OVT sorbents demonstrated high efficiency in the sorption of ibuprofen, and the maximum percent removal was higher than 92% for VT-EHDDMA and VT-HDTMA, with a maximum sorption capacity of 52 ± 2 mg g−1 (VT-EHDDMA) and 54 ± 2 mg g−1 (VT-HDTMA), whereas 16 ± 2 mg g−1 was observed for VT. These results suggest that the low-cost OVT could be considered as appropriate sorbent for ibuprofen removal from aqueous medium, and probably as a promising sorbent for drugs of a wide polarity range, with neutral, acid and basic characteristics.