Are Titania Photocatalysts and Titanium Implants Safe? Review on the Toxicity of Titanium Compounds

Titanium and its compounds are broadly used in both industrial and domestic products, including jet engines, missiles, prostheses, implants, pigments, cosmetics, food, and photocatalysts for environmental purification and solar energy conversion. Although titanium/titania-containing materials are usually safe for human, animals and environment, increasing concerns on their negative impacts have been postulated. Accordingly, this review covers current knowledge on the toxicity of titania and titanium, in which the behaviour, bioavailability, mechanisms of action, and environmental impacts have been discussed in detail, considering both light and dark conditions. Consequently, the following conclusions have been drawn: (i) titania photocatalysts rarely cause health and environmental problems; (ii) despite the lack of proof, the possible carcinogenicity of titania powders to humans is considered by some authorities; (iii) titanium alloys, commonly applied as implant materials, possess a relatively low health risk; (iv) titania microparticles are less toxic than nanoparticles, independent of the means of exposure; (v) excessive accumulation of titanium in the environment cannot be ignored; (vi) titanium/titania-containing products should be clearly marked with health warning labels, especially for pregnant women and young children; (vi) a key knowledge gap is the lack of comprehensive data about the environmental content and the influence of titania/titanium on biodiversity and the ecological functioning of terrestrial and aquatic ecosystems

Relationships Between Fungal Contamination and Some Physicochemical Properties of Rapeseeds

The aim of this study was to evaluate some properties of rapeseed, to determine the amount of fungi including thermotolerant and xerophilic species and to specify the correlations between some physical properties of rapeseed and the number of fungi. Material was 18 samples of rapeseeds. The characteristics of seeds included volumetric weight, impurities, pH, moisture, water activity, fat content, fat acidity and critical moisture of seeds. Number of fungi were investigated on RBA, YpSs, DG18 medium at 25, 37 and 45°C. Differences between amount of rapeseed impurities and fat acidity have been revealed. The number of fungi was diversified depending on medium and incubation temperature. The largest fungi number was isolated on DG18 at 25°C. Correlations between physicochemical properties of seeds and number of isolated fungi have been pointed out. Our study demonstrated that low pH values and weight by volume of seeds as well as high acidity of fat can be used as indicators of contamination of rapeseeds by fungi

Nanomaterials for Environmental Purification and Energy Conversion

Nanomaterials, engineered structures of which a single unit is sized (in at least one dimension) between 1 to 100 nm, are probably the fastest growing market in the world [...

The Influence of The Light-Activated Titania P25 on Human Breast Cancer Cells

Cosmetics and other daily care products contain titanium(IV) oxide (titania). Since multiple risk factors can increase the chance of developing cancer, an evaluation of titania safety has become a matter of concern in recent times. However, it should be pointed out that titania as an efficient photocatalyst has been also applied for inactivation of various pathogens, environmental purification and energy conversion, which might result in significant improvement of human life. Therefore, it is worth considering titania not only as a possible cancer initiator, but also as an efficient solution against cancer cells. Accordingly, in this study, the effect of commercial titania photocatalyst P25 (Degussa/Evonik) on breast adenocarcinoma MCF7 cells (ATCC (R) HTB-22 (TM), breast adenocarcinoma cell line from human) has been investigated. The cells were treated with titania at doses of 10, 30, and 50 mu g/mL under UVA/vis irradiation and in the dark. The significant morphological alterations in living cells were observed for larger doses of titania, such as changes in the shape and the size of cells, the deviation from the normal structure, and an increase in cells' mortality. Moreover, the effect was significantly higher under irradiation than in the dark confirming strong photocatalytic activity of titania P25. In contrast, the lowest dose of titania (10 mu g/mL) did not exhibit a significant impact on MCF7 cells, similarly to the nontreated cells. Accordingly, it has been proposed that locally applied titania might be considered for a cancer therapy after necessary in vivo tests to estimate any possibilities of side effects

Nanomaterials for Environmental Purification and Energy Conversion

The Special Issue, “Nanomaterials for Environmental Purification and Energy Conversion”, describes the significant and increasing role of nanomaterials in catalysis. It is believed that the most important factor for future human development could be to use nanomaterials (nanotechnology) to solve such critical issues facing humanity such as environment, water and energy. It should be also pointed out that properties of nanomaterials differ substantially from that of bulk materials of the same composition, resulting in high reactivity. Therefore, it creates new perspectives for the catalytic processes in the broad sense. This issue was mainly dedicated as a platform for the contributions from The Symposium on Nanomaterials for Environmental Purification and Energy Conversion (SNEPEC), which was held in Sapporo, Japan in winter 2018. Accordingly, this book compiles the current state-of-the-art of research in the area of novel photocatalysts and highlights current research directions in the fields of advanced oxidation technologies, material science and nanotechnology. Written by leading experts in the field of photochemistry and chemical engineering, a collection of 17 papers, including 16 research papers and one review, covers a broad range of topics focusing on the exceptional role of catalytic nanomaterials in solving environmental and energy problems of modern societies. The majority of papers present the importance of photocatalytic nanomaterials, especially for degradation of organic pollutants and inactivation of microorganisms, but there is also a strong representation of conventional catalysis, based on nanomaterials for important processes such as catalytic hydrogen production and organic synthesis

TiO2-Modified Magnetic Nanoparticles (Fe3O4) with Antibacterial Properties

This paper presents the synthesis and characteristics of Fe3O4/C/TiO2 hybrid magnetic nanomaterials with antibacterial properties. The materials used were obtained using a microwave-assisted two-stage precipitation method. In the first stage, magnetite nanoparticles (Fe3O4) were prepared with the precipitation method, during which an additional glucose layer was placed on them. Next, the surface of Fe3O4 nanoparticles was covered by TiO2. It was observed that the addition of carbon and titanium dioxide caused a decrease in the average size of magnetite crystallites from 15.6 to 9.2 nm. Materials with varying contents of anatase phase were obtained. They were characterized in terms of phase composition, crystallite size, specific surface area, surface charge and the kinds of function groups on the surface. The results show a successful method of synthesizing hybrid magnetic nanoparticles, stable in a solution, with antibacterial properties under direct solar light irradiation. Compared to classical materials based on TiO2 and used for water disinfection, the obtained photocatalytic nanomaterials have magnetic properties. Owing to this fact, they can be easily removed from water once their activity under direct irradiance in a given process has completed

Stability of selenium diet supplement

Selenium is one of the trace elements playing a crucial role in a proper function of living organisms. Selenium intake varies, largely based on the selenium content of food. The daily Se intake recommended for adults amounts to 55 μg per day. The mean level of selenium in the population varies considerably between countries. Recent studies on the selenium dietary intakes in Poland showed that it is not sufficient to meet the daily requirement for this microelement so it is strongly recommended to employ selenium supplementation. The commercial product SEL-BRCA1® being a selenium diet supplement was subjected to chemical and microbial analysis to determine its stability in storage time and conditions. Basing on the obtained results it can be stated that the stability of studied supplement, stored in the closed bottles, can be confirmed for the period of time up to 45 months after the production date and it is not recommended to store opened bottles for the period of time longer than 12 months. The studied supplement showed a very high microbial stability what underscores its usefulness as human medicines

Photocatalytic Decomposition of Acetaldehyde on Different TiO2-Based Materials: A Review

Purification of air from the organic contaminants by the photocatalytic process has been confirmed to be very perspective. Although many various photocatalysts have been prepared and studied so far, TiO2 is still the most commonly used, because of its advantageous properties such as non-toxicity, relatively low cost and high stability. Surface modifications of TiO2 were extensively proceeded in order to increase photocatalytic activity of the photocatalyst under both UV and visible light activations. The intention of this review paper was to summarize the scientific achievements devoted to developing of TiO2-based materials considered as photocatalysts for the photocatalytic degradation of acetaldehyde in air. Influence of the preparation and modification methods on the parameters of the resultant photocatalyst is reviewed and discussed in this work. Affinity of the photocatalyst surfaces towards adsorption of acetaldehyde will be described by taking into account its physicochemical parameters. Impact of the contact time of a pollutant with the photocatalyst surface is analyzed and discussed with respect to both the degradation rate and mineralization degree of the contaminant. Influence of the photocatalyst properties on the mechanism and yield of the photocatalytic reactions is discussed. New data related to the acetaldehyde decomposition on commercial TiO2 were added, which indicated the different mechanisms occurring on the anatase and rutile structures. Finally, possible applications of the materials revealing photocatalytic activity are presented with a special attention paid to the photocatalytic purification of air from Volatile Organic Compounds (VOCs)