Titanium dioxide (TiO2) is a material of diverse applications commonly used as a food additive or cosmetic ingredient. Its prevalence in products of everyday use, especially in nanosize, raises concerns about safety. Current findings on the safety of titanium dioxide nanoparticles (TiO2 NPs) used as a food additive or a sunscreen compound are reviewed and systematized in this publication. Although some studies state that TiO2 NPs are not harmful to humans through ingestion or via dermal exposure, there is a considerable number of data that demonstrated their toxic effects in animal models. The final agreement on the safety of this nanomaterial has not yet been reached among researchers. There is also a lack of official, standardized guidelines for thorough characterization of TiO2 NPs in food and cosmetic products, provided by international authorities. Recent advances in the application of ‘green-synthesized’ TiO2 NPs, as well as comparative studies of the properties of ‘biogenic’ and ‘traditional’ nanoparticles, are presented. To conclude, perspectives and directions for further studies on the toxicity of TiO2 NPs are proposed.

Contamination of the environment has been a growing problem in recent years. Due to the rapid growth in human population, the expansion of cities, along with the development of industry, more and more dangerous chemicals end up in the environment, especially in soil and water. For the most part, it is not possible to effectively remove chemicals through traditional remediation techniques, because those used in treatment plants are not specifically designed for this purpose. Therefore, new approaches for water remediation are in great demand. Many efforts have been focused on applications of photocatalysis for the remediation of chemical pollutants including drugs. Titanium(IV) oxide nanoparticles have particularly been considered as potential photocatalysts due to their favorable properties. In this article, we present the problem of emerging contaminants including drugs and discuss the use of photocatalysts based on titanium(IV) oxide nanoparticles for their degradation. A wide selection of materials, starting from bare TiO2, via its hybrid and composite materials, are discussed including those based on carbonaceous materials or connections with macrocyclic structures. Examples of photodegradation experiments on TiO2-based materials including those performed with various active pharmaceutical ingredients are also included.

The natural environment is constantly under threat from man-made pollution. More and more pharmaceuticals are recognized as emerging pollutants due to their growing concentration in the environment. One such chemical is ibuprofen which has been detected in processed sewage. The ineffectiveness of water methods treatment currently used raises the need for new remediation techniques, one of such is photodegradation of pollutants. In the present study, zinc(II) and copper(II) phthalocyanines were grafted onto pure anatase TiO2 nanoparticles (5 and 15 nm) to form photocatalysts for photodecomposition of ibuprofen in water. The nanoparticles were subjected to physicochemical characterization, including: thermogravimetric analysis, X-ray powder diffraction, X-ray photoelectron spectroscopy, Brunauer–Emmett–Teller surface area analysis and particle size measurements. In addition, they were assessed by means of electron spin resonance spectroscopy to evaluate the free radical generation. The materials were also tested for their photocatalytic activity under either UV (365 nm) or visible light (665 nm) irradiation. After 6 h of irradiation, almost complete removal of ibuprofen under UV light was observed, as assessed by liquid chromatography coupled to mass spectrometry. The reaction kinetics calculations revealed that the copper(II) phthalocyanine-containing nanoparticles were acting at a faster rate than those with zinc(II) derivative. The solutions after the photoremediation experiments were subjected to Microtox® acute toxicity analysis.

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In this work, a composite material based on titanium(IV) oxide and iron(II,III) oxide was prepared using mechanothermal method. The obtained composite system was thoroughly characterized using techniques such as scanning electron microscopy, X-ray powder diffraction, thermogravimetric analysis, and nanoparticle tracking analysis. The acute toxicity of the composite material was evaluated with Microtox. In addition, the material’s photocatalytic potential was studied in photodegradation tests of ibuprofen. The composite system revealed magnetic properties of potential usage in its recovery after photocatalytic tests. However, the photocatalytic activity of TiO2–Fe3O4 was lower than that of bare TiO2. In the photocatalytic tests performed under UV (365 nm) light, a 44% reduction of initial ibuprofen concentration in the sample was noted for bare TiO2, while for TiO2–Fe3O4 composite, only a 19% reduction was observed. In visible light (525 nm), both materials achieved statistically insignificant photodegradation rates, which was contrary to the anticipated effect for TiO2–Fe3O4. The observation was explained by a side oxidation reaction of Fe3O4 to Fe2O3 by the generated reactive oxygen species (ROS) in the photocatalytic process, which significantly diminished the amount of available ROS for ibuprofen degradation. The oxidation process appearing within TiO2–Fe3O4 was evident and easily observed as the color of the material turned from gray to brown. Acute toxicity assay performed with the use of Microtox revealed reduced toxicity of TiO2–Fe3O4 (32% inhibition of the Aliivibrio fischeri bacteria cell viability according to bioluminescence emitted) when compared to bare Fe3O4 (56% inhibition), whereas bare TiO2 was non-toxic. In the study, the processes occurring during the photocatalytic reaction were analyzed and discussed in the context of the available literature data.

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