Figure 2

Retention factor (Rf) obtained from thin layer chromatography experiments using SiOH, SiNH2 and SiCOOH as stationary phases. The mobile phase included hexane (Hex), dichloromethane (DCM), ethyl acetate (EtAc), ethanol, (EtOH) or acetic acid (AcOH) (a). Isotherms for thymol adsorption at 25 °C on the biogenic silica carriers, SiOH, SiNH2 and SiCOOH (b). TGA curves showing the initial higher thermal stability of thymol adsorbed on BSiO2 (c), and DTA curves highlighting its loading in a molecular level (d).