Adsorption of Carvone and Limonene from Caraway essential oil onto Tunisian montmorillonite clay for pharmaceutical application

To explore a novel kind of green composite material having excellent antibacterial, antifungal ability and specific-targeting capability for pharmaceutical uses, a novel kind of bio-composite was prepared using sodium purified clay as carrier of Caraway essential oil (CEO). Gas chromatography-mass spectroscopy (GC–MS) analyses of CEO reveals that Carvone (68.30%) and Limonene (22.54%) are the two major components with a minimum inhibitory concentration (MIC) value equal to 125 mg/mL against Staphylococcus (S) aureus bacteria and Candida albicans fungi. Clay from Zaghouan was purified and characterized by X-ray Photoelectron Spectroscopy (XPS), X-ray diffraction (XRD), Fourier transformed infrared spectroscopy (FT-IR) and N2 adsorption–desorption (BET method). Results obtained by chromatograph equipped with a flame ionization detector (GC-FID) show that the concentration of 130 mg/mL of essential oil and 5 h of contact with the purified clay are the optimal conditions for the bio-hybrid formation. The pseudo-second-order model can describe the kinetic study of the adsorption of Carvone and Limonene on sodium montmorillonite, and the adsorption isotherms have been established to the Langmuir type. Limonene registers a maximum adsorption value equal to 3.05 mg/g of clay however Carvone register the higher amount of adsorption (19.98 mg/g) according to its polarity and the abundance of this compound in the crude CEO. X-ray diffraction, Fourier transformed infrared spectroscopy, elemental analyses (CHN) and X-ray fluorescence characterization valid the success adsorption of CEO in sodium montmorillonite surface. The purified clay/CEO hybrid (purified clay/CEO) combined the advantages of both the clay and the essential oil used in exerting the antibacterial and antifungal activity, and thus, the composite has a double antibacterial and antifungal activity compared to the separately uses of inactive clay and CEO, suggesting the great potential application in pharmaceutical treatments.