Development of photocatalytic paint based on TiO2 and photopolymer resin for the degradation of organic pollutants in water.

While the use of TiO2 nanoparticles in the form of slurry/suspension requires energy-intensive separation processes, its immobilization in solid support may open new opportunities in the area of sustainable water treatment technologies. In this study, a novel method for the development of photocatalytic paint based on TiO2 nanoparticles and acrylate-based photopolymer resin is reported. The paint (TiO2@polymer) was applied on substrates such as plastic petri dish and glass jar, which was polymerized/solidified by ultraviolet light irradiation. The painted petri dish and glass jar were used for the photocatalytic degradation of model organic pollutants viz. methyl orange (MO), methylene blue (MB), and indole in deionized water, simulated fresh drinking water, and tap water matrices. The photocatalytic degradation studies were performed under sunlight and UV-B light were used for. The sunlight-assisted photocatalytic degradation of MO and MB was found to be faster and more efficient than the UV-B light-assisted ones. Under UV-B light irradiation, it took 120 min to degrade about 80% of 6 ppm MB solution, whereas under sunlight irradiation it took 60 min to degrade about 90% of the same MB solution. The photocatalytic paint generated hydroxyl radical (·OH) under the UV-B and sunlight irradiation, which was studied by the terephthalic acid fluorescence tests. Further, the potential release of TiO2 during the exposure to UV irradiation was studied by single particle ICP-MS analysis.

Sucrose-Mediated Fast Synthesis of Zinc Oxide Nanoparticles for the Photocatalytic Degradation of Organic Pollutants in Water.

We report a facile method for the synthesis of zinc oxide nanoparticles (nZnOs) by rapidly heating a paste of zinc nitrate and sucrose on the hot plate at 500 °C. The transmission electron microscopy images revealed the spherical shape of the nZnO with an average size of 35 nm. The band gap and the specific surface area of the nZnO were measured to be about 3.32 eV and 80.11 m2/g, respectively. The nZnO was utilized for the photocatalytic degradation of methyl orange (MO) and methylene blue (MB) in water under the ultraviolet (UV-B) light and sunlight irradiation. Photocatalysis was performed in two types of water matrices, viz., the deionized water and the simulated fresh drinking water. Almost a complete degradation of MO and MB was obtained within 30 min of UV-B light irradiation. Under sunlight irradiation, more than 95% of the MO solution underwent degradation within 30 min. The photocatalytic stability of the nZnO was examined for five cycles, and a similar activity was found throughout the cycles. The photocatalytic generation of the hydroxyl radical (•OH) was confirmed by the terephthalic acid photoluminescence tests. Moreover, the synthesis methodology was validated by triplicating the nZnO synthesis. Every time, the nZnO demonstrated a similar photocatalytic activity, which confirmed the robustness of the synthesis procedure.