Martin Morgeneyer

Emission of titanium dioxide nanoparticles from building materials to the environment by wear and weather.

In the present work, we investigate the effect of weathering duration on a commercial photocatalytic nanocoating on the basis of its nanoparticle emission tendency into two media, air and water. It is found that increased weathering duration results in stepwise structural deterioration of the nanocoating, which in turn decreases the nanocoating life, changes the nanocoating removal mechanism, and increases the particle emission concentration. Emission of free TiO2 nanoparticles is found to be weathering duration dependent. Three quantities are introduced: emission transition pace (ETP), stable emission level (SEL), and stable emission duration (SED). By linear extrapolation of these quantities from short weathering durations, complete failure of the nanocoatings can be predicted and, moreover, the potential increase of nanoparticles release into the air.

A review on the study of the generation of (nano)particles aerosols during the mechanical solicitation of materials

This paper focuses on presenting the forefront of the interdisciplinary studies conceived towards the generation of the wear particles aerosol when materials are subjected tomechanical stresses. Various wear mechanisms and instrumentation involved during stress application and aerosolization of wear particles, as well as particles characterization, measurement, and modeling techniques are presented through the investigation of a series of contextual works which are emphasized on the identification of these aspects. The review is motivated from the fact that understanding mechanisms involved in wear-induced particle generation, both at nanoand at microscale, is important for many applications that involve surfaces sliding over each other due to various potential health aspects. An attempt has been made to explain how the information based on this broad spectrum of subjects discovered in this contribution can be used and improved in order to produce a more resilient, rational, and versatile knowledge base which has been found lacking in the present literature during its survey. The area of study is highly multidisciplinary since it involves aerosol, particle, and material sciences.

Environmental release of engineered nanomaterials from commercial tiles under standardized abrasion conditions

The study presented here focuses on commercial antibacterial tiles whose emissivity of (nano) particles due to abrasion has yet barely been investigated. The tiles have been characterized regarding their surface properties and composition throughout their chain-of-use, i.e. from their state of commercialization until the experimental end-of-service life. In contrast to plane standard tiles, their surfaces form hilly surfaces. In the depressions, titanium dioxide is found at the surface, thus theoretically protected by the hilly areas against abrasion on the tiles surface. Furthermore, a deposition technique has been put in place by producers allowing for coating the before mentioned commercial tiles with titanium dioxide, thus being similar to those commercially available. It consists in depositing titanium dioxide on the surface, latter one allowing fixing the first. This development allows for better understanding the future options for product formulation and thus improvement with respect to particle release. The tests reveal the aerosolization from commercial antibacterial tiles of micronic and submicronic particles in the inhalable region or particles that can subjected to be released in the environment (<10μm). The aersolization of the particles from the coated tiles was found to be significantly higher compared to the non coated tiles.

Experimental study of the aerosolization from a carbon nanotube bulk by a vortex shaker

The growing use of nanomaterials requires the development of tools enabling study of the risks to consumer, worker, and environment. This study relates to the risk of suspension of inhalable particles upon production and/or use of powders constituted of nanoobjects, and more specifically to the potential of the vortex shaker as apparatus for determining the dustiness of a powder and as atmosphere generating tool for experimental toxicology. The powder chosen for this study was Graphistrength C100 (ARKEMA), a multiwalled carbon nanotube. Its agitation in a vortex shaker at 1500 rpm leads to an aerosol divided into four families, from isolated fibres to micronic pellets. The study highlights that the speed of agitation and the geometry of the device are influential parameters, to be systematically taken into account. It concludes that while the technique seems mature to conduct C100 dustiness tests, developments are still necessary to use it routinely for toxicology studies.

Evaluation of the particle aerosolization from n-TiO 2 photocatalytic nanocoatings under abrasion

A parametric study on the release of titanium dioxide (TiO2) nanoparticles from two commercial photocatalytic nanocoatings is carried out. For this, abrasion tests are performed on them. The formed aerosols are characterized by their number concentration, particle size distribution, individual particle shape, size, and chemical composition. The two nanocoatings appear to exhibit contrastingly opposite behavior with respect to the number concentration of the released particles. Having irregular shapes, the released particles are found to have unimodal size distributions with 1.5-3.5% (in mass) of Ti content. However, no free nanoparticles of TiO2 were found. Distinct phases during the particle number concentration evolution with time are also discussed and evaluated. Two quantities--(ΔC/Δt)I and TII--are identified as the important indicators to qualitatively measure the resistance strength and hence the concentration of the released particles from a nanocoating during stress application.

Examples and Case Studies

Release of nanomaterials may occur during any stage of the life-cycle and can eventually lead to exposure to humans, the environment or products. Due to the large number of combinations of release processes and nanomaterials, release scenarios can currently only be tested on a case-by-case basis. This chapter presents five case studies on nanomaterial release under different conditions. While two of the case studies investigate the potential release under well-defined laboratory conditions in order to obtain a clearer picture on the release processes, the other three studies measure the potential release in real workplaces. By combining these two approaches, it is possible to gather more information on release of and exposure to nanomaterials to eventually group the different release processes and scenarios, which will significantly simplify the investigations.

Exposure assessment based recommendations to improve nanosafety at nanoliposome production sites

The NANOFOL concept aims at creating nanodevices containing a drug for inflammatory disorder treatment. This paper provides recommendations for nanosafety based on a measurement campaign which aimed at identifying exposure risks with respect to two specific phases of the products lifecycle, that is, production of the device and its waste management. The nanoparticles presence both in air and in liquid phase was studied. While no emissions were detected during the production period, many recommendations have been made, particularly regarding the nanowaste treatment, based on nanosafety guidelines.

Development of an Experimental Setup for the Measurement of the Coefficient of Restitution under Vacuum Conditions

The Discrete Element Method is used for the simulation of particulate systems to describe and analyze them, to predict and afterwards optimize their behavior for single stages of a process or even an entire process. For the simulation with occurring particle-particle and particle-wall contacts, the value of the coefficient of restitution is required. It can be determined experimentally. The coefficient of restitution depends on several parameters like the impact velocity. Especially for fine particles the impact velocity depends on the air pressure and under atmospheric pressure high impact velocities cannot be reached. For this, a new experimental setup for free-fall tests under vacuum conditions is developed. The coefficient of restitution is determined with the impact and rebound velocity which are detected by a high-speed camera. To not hinder the view, the vacuum chamber is made of glass. Also a new release mechanism to drop one single particle under vacuum conditions is constructed. Due to that, all properties of the particle can be characterized beforehand.