Abstract
Hetero-photocatalytic graphene-TiO2 materials have, in the literature, been found to possess better photocatalytic activity for environmental applications compared to pure TiO2. These types of materials can be prepared in different ways; however, their photocatalytic performance and quality are not easily controlled and reproduced. Therefore, we synthetized graphene oxide-TiO2 nanoparticles by sol-gel reaction from TiCl4, as precursor, with two different methods of synthesis and with a graphene oxide (GO) loading ranging from 0 to 1.0. This approach led to a good adhesion of GO to TiO2 through the Ti-O-C bonding, which could enhance the photocatalytic performances of the materials. Overall, 0.05 wt % GO loading gave the highest rate in the photodegradation of phenol under visible light, while higher GO loadings had a negative impact on the photocatalytic performances of the composites. The 0.05 wt % GO-TiO2 composite material was confirmed to be a promising photocatalyst for water pollutant abatement. The designed synthetic approach could easily be implemented in large-scale production of the GO-TiO2 coupling materials.
Highlights
More than 80% of wastewater around the world is today released to the environment without appropriate treatment [1]
After preparing graphene oxide (GO) via a modified Hummers method from a natural graphite powder (UF2 99,5 Graphit Kropfmühl GmbH, Hauzenberg, Germany) as described elsewhere, [10], the graphene-titanium dioxide (GT) composites were synthesized by two methods, namely in static conditions (GTS) and in a stirred tank (GTD), and their properties were compared
A pure TiO2 reference, TS, was prepared by the statistic method, in the same conditions used for the GTS composites with no GO in the starting mixture
Summary
More than 80% of wastewater around the world is today released to the environment without appropriate treatment [1]. Phenolic compounds are among the possible pollutants that impact natural aquatic systems. Advance tertiary wastewater treatment technologies are still costly and often require consumption of additional chemicals and energy [2,3] In this context, solar photocatalysis has the potential to offer feasible solutions for the abatement of phenols and other emerging pollutants [6]. As reported in our previous work [10] and by other authors [6,9,11], in-situ nucleation and growth of TiO2 nanoparticles on GO sheets allows achieving strong Ti-O-C chemical linkage between the two materials, and enhances photocatalytic activity. The synthesis conditions have a strong impact on the structure of the photocatalysts, and on their ability to degrade water pollutants [12]. It was possible to compare the morphology and the photocatalytic performances of the materials prepared under stirring and in static conditions
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