Recovery of hydroxytyrosol onto graphene oxide nanosheets: Equilibrium and kinetic models

Abstract

In this study, a novel nanomaterial, graphene oxide (GO), which has never been used as an adsorbent in the separation of hydroxytyrosol (HT), has been utilized. GO nanosheets were synthesized by graphite oxidation naturally, which is known as modified Hummer's method. Then, the material obtained was characterized by Fourier transform infrared spectroscopy (FTIR) and X-ray diffraction (XRD) methods. Adsorption of HT from aqueous media onto synthesized GO was found to be >85% under optimum conditions (with 0.01 mg GO in 10 mL of solution at 150 rpm for 1440 min, where pH is 9). On the other hand, equilibrium (Langmuir, Freundlich, Temkin, Dubinin-Radushkevich and Redlich-Peterson) and kinetic (pseudo-first order, pseudo-second order, Elovich and intra-particle diffusion) models have been applied for analysis and representation of data. Thermodynamic findings point out that the related adsorption system is exothermic, applicable and spontaneous. (C) 2019 Elsevier B.V. All rights reserved.