Preparation, evaluations and operating conditions optimization of nano TiO2 over graphene based materials as the photocatalyst for degradation of phenol

Abstract

The preparation of the TiO2@graphene nanocomposites is significant due to its applications in the various industries such as sensor and catalytic purposes. In this study, the TiO2 and graphene-based nanocomposites have been synthesized via a simple one-step hydrothermal procedure by use of two precursors for graphene in water and ethanol as the solvents. Our fabricated photocatalysts are eco-friendly and can be recovered easily. Besides, a comparative study between graphene (GR) and graphene oxide (GO) as the graphene precursors for the photocatalytic degradation of phenol was performed. The obtained TiO2 and graphene-based nanocomposites were characterized by XRD, FESEM, EDX, FTIR, BET, NH3-TPD, PL, Raman, EDS and TGA techniques. In addition, the central composite design coupled with the response surface methodology by the Design Expert software was employed to design the experiments, optimization, and modeling of phenol decomposition. The influences of the process variables including the; solution pH, initial phenol concentration and photocatalyst amount on phenol degradation were investigated by the response surface method. In order to examine the provided model, an analysis of variance was performed for linear and quadratic equations for GO and GR-based photocatalysts in which satisfy the statistical criteria. The titanium-graphene nanocomposites has been demonstrated more photocatalytic performance than bare TiO2. It was found that a strong coupling between TiO2 nanoparticles and graphene sheets was formed. As compared with the pristine TiO2, the photocatalytic performance of the selected GO-based catalyst improved about 28% and GR-based photocatalyst increased about 15% for degradation of phenol. The empirical model and optimum conditions for the phenol degradation were obtained. Moreover, the as-synthesized photocatalysts can be recovered easily and reuse several times through the phenol degradation.