Abstract
A series of reduced graphene oxide-TiO2 composites (rGO-TiO2) were prepared by hydrothermal treatment using graphite and titanium isopropoxide as raw materials. The structural, surface, electronic, and optical properties of the prepared composites were extensively characterized by N2 adsorption, FTIR, XRD, XPS, Raman spectroscopy, and DRS. GO was found to be effectively reduced and TiO2 to be in pure anatase phase in all composites obtained. Finally, experiments were performed to evaluate the effectiveness of these new materials as photocatalysts in the degradation of ethylparaben (EtP) by UV radiation. According to the band-gap energies obtained (ranging between 3.09 eV for 4% rGO-TiO2 to 2.55 eV for 30% rGO-TiO2), the rGO-TiO2 composites behave as semiconductor materials. The photocatalytic activity is highest with a rGO content of 7 wt% (7% rGO-TiO2), being higher than observed for pure TiO2 (Eg = 3.20 eV) and achieving 98.6% EtP degradation after only 40 min of treatment. However, the degradation yield decreases with higher percentages of rGO. Comparison with rGO-P25 composites showed that a better photocatalytic performance in EtP degradation is obtained with synthesized TiO2 (rGO-TiO2), probably due to the presence of the rutile phase (14.1 wt %) in commercial P25.
Highlights
Pharmaceutical and personal care products are extensively used worldwide and continuously released through wastewaters
Conclusions reduced graphene oxide (rGO)-TiO2 composites with different percentages of rGO were successfully prepared using a simple hydrothermal method
The surface area and porosity are more developed in the rGO-TiO2 composites than in the graphene oxide (GO)-P25 composites
Summary
Pharmaceutical and personal care products are extensively used worldwide and continuously released through wastewaters. These emerging pollutants cannot generally be removed by conventional wastewater treatment processes, and they have been found in treated waters and treatment plant sludge at low concentrations (ppb or ppm) [1]. 0.4% (p/p) for individual parabens and 0.8% (p/p), expressed as p-hydroxybenzoic acid, for paraben mixtures [2]. These composites are readily biodegradable under aerobic conditions, they can be considered as “pseudo-persistent” pollutants due to their high consumption and continuous release in the environment.
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