Search

In this work, nanocomposites based on titanium dioxide and reduced graphene oxide (TiO2@rGO) with different weight percentages of rGO (4, 8, and 16 wt%) were prepared by the hydrothermal/solvothermal synthesis method and thermally treated at 300 °C. The prepared nanocomposites were explored for the removal of methylene blue dye (MB) in the presence of simulated solar illumination as well as natural sunlight. The structural, morphological, chemical, and optical properties of the as-synthesized TiO2@rGO nanocomposites were characterized. The obtained results of the graphene-based nanocomposite materials indicated the existence of interactions between TiO2 and rGO, i.e., the Ti–O–C bond, which confirmed the successful integration of both components to form the TiO2@rGO nanocomposites. The addition of rGO increased the specific surface area, decreased the band gap energy, and increased the photocatalytic degradation efficiency of MB from water compared to TiO2 nanoparticles. The results of photocatalytic activity indicated that the amount of rGO in the prepared TiO2@rGO nanocomposites played a significant role in the application of different photocatalytic parameters, including the initial dye concentration, catalyst concentration, water environment, and illumination source. Our studies show that the reinforcement of the nanocomposite with 8 wt% of rGO allowed us to obtain the maximum photocatalytic decomposition performance of MB (10 mg·L−1) with a removal percentage of 99.20 after 2 h. Additionally, the obtained results show that the prepared TiO2@rGO_8 wt% nanocomposite can be used in three consecutive cycles while maintaining photocatalytic activity over 90%. [ABSTRACT FROM AUTHOR]

This work presents the immobilisation of titanium dioxide (TiO2) nanoparticles (NPs) and reduced graphene oxide (rGO)-TiO2 nanocomposite on glass sheets for photocatalytic degradation of methylene blue (MB) under different radiation sources such as ultraviolet and simulated solar radiation. The TiO2 NPs and rGO-TiO2 nanocomposite were synthesised through a simple hydrothermal method of titanium isopropoxide precursor followed by calcination treatment. Deposition of prepared photocatalysts was performed by spin-coating method. Additionally, ethylene glycol was mixed with the prepared TiO2 NPs and rGO-TiO2 nanocomposite to enhance film adhesion on the glass surface. The photocatalytic activity under ultraviolet and simulated solar irradiation was examined. Further, the influence of different water matrices (milli-Q, river, lake, and seawater) and reactive species (h+, •OH, and e−) on the photocatalytic efficiency of the immobilised rGO/TiO2 nanocomposite was careful assessed. MB dye photocatalytic degradation was found to increase with increasing irradiation time for both irradiation sources. The immobilisation of prepared photocatalysts is very convenient for environment applications, due to easy separation and reusability, and the investigated rGO/TiO2-coated glass sheets demonstrated high efficiency in removing MB dye from an aqueous medium during five consecutive cycles. [ABSTRACT FROM AUTHOR]

Plastic, which was not so long ago considered the material of the future, is today one of the biggest environmental problems. The most common type of primary microplastics that enters the aquatic environment in large numbers are fibers released during the washing of synthetic textiles. Due to their small size, they do not enter the ecosystem only through wastewater, but also through sewage treatment plants. In the present work, we tested a method for the degradation of microplastics from the wastewater of a washing machine, which is based on photocatalysis. In our study, the photocatalytic degradation of polyethylene terephthalate (PET) and polyamide (PA) fibers was carried out for 48 hours in a coved quartz beaker. The beaker contained fibers, 5 mg of TiO2 as a photocatalyst, 5 mL of Milli-Q water and a stirrer. In a photocatalytic reactor, quartz beakers were placed on a magnetic stirrer and irradiated with simulated sunlight (lamp: ULTRA-VITALUX, 230 V, 300 W, Osram). After photocatalysis, plastic samples were taken from the suspension and air-dried in a dust-free chamber. SEM analysis after photocatalytic degradation showed that the surface of the fibers became rough with clear signs of degradation, which could not be observed in the original ones. Cross-sectional FIB-SEM analysis revealed details of the damage. Changes in the chemical structure was analyzed by Raman spectroscopy, and ICP-MS analysis was used to analyze the amount of finer microplastic fiber fragments released into the suspension. In the future work, the presented degradation process will also be tested on real samples, which consist of different types of microplastic (PET, PA) and cotton fibers. [ABSTRACT FROM AUTHOR]