Industrial Applications of Nanomaterials

Sabu Thomas, Yves Grohens, Yasir Beeran Pottathara, Sabu Thomas, Yves Grohens, Yasir Beeran Pottathara

• Publisher: Elsevier
• Year: 2019
• Print ISBN: 9780128157497
• eBook ISBN: 9780128157503
• Topic: Tecnología e ingeniería
• Subtopic: Ciencias de los materiales

Industrial Applications of Nanomaterials explains the industry based applications of nanomaterials, along with their environmental impacts, lifecycle analysis, safety and sustainability. This book brings together the industrial applications of nanomaterials with the incorporation of various technologies and areas, covering new trends and challenges. Significant properties, safety and sustainability and environmental impacts of synthesis routes are also explored, as are major industrial applications, including agriculture, medicine, communication, construction, energy, and in the military. This book is an important information source for those in research and development who want to gain a greater understanding of how nanotechnology is being used to create cheaper, more efficient products. - Explains how different classes of nanomaterials are being used to create cheaper, more efficient products - Explores the environmental impacts of using a variety of nanomaterials - Discusses the challenges faced by engineers looking to integrate nanotechnology in new product development

Chapter 1

Nanomaterials in industry—How to assess the safety?

Heli Kangas; Marja Pitkänen VTT Technical Research Centre of Finland Ltd, Espoo, Finland

Abstract

Nanomaterials have created increased interest in various industrial applications due to their unique properties compared to the same bulk materials. These properties are the result of their physicochemical properties such as small size and high specific surface area. However, while providing novel functions in applications, their interactions with their biological surroundings can be unpredictable and some concern about their safety has been raised. The rapid technological development has also left the legislation lacking behind and currently, there are no binding regulations regarding the safety assessment explicit for nanomaterials. Manufacturers of nanomaterials and products containing thereof are responsible for ensuring their safety. Existing legislation, guidelines, and standards provide a basis for the safety assessment, while published risk assessment protocols provide a tool to evaluate the hotspots and knowledge gaps in the processes involving nanomaterials.

Keywords

Safety; Risk assessment; Hazard; Exposure; Cellulose nanofibril; Composite; Food contact material

1 Introduction

Nanomaterials have unique, so-called nano-specific properties, compared to their corresponding bulk materials, due to their small size, high specific surface area, etc. These properties make them interesting for many applications, novel or already existing. However, the same properties are responsible for their potentially different behavior compared to the same materials of larger size. For example, a decrease in particle size can be related with improved penetration through biological barriers, resulting in increased amounts of the materials in various cellular compartments and their transfer into new locations, such as the brain [1]. The agglomeration state of fibrous nanomaterials has also found to play a decisive role in the material toxicity [2–4]. In addition, it is evident that the large surface area of nanomaterials may lead to enhanced interactions with their biological surroundings. It is also noteworthy to consider the biological identity of the nanomaterials, which is different from the synthetic identity of pristine nanomaterials. The biological identity is adopted when nanomaterials enter the biological systems due to absorption of biomolecules and formation of bio-corona on the surface [5]. The safety of nanomaterials thus depends on many, still poorly understood factors, such as their physicochemical properties, the size and shape of the particles, their aggregation properties, reactivity, and specific surface properties among others. In addition, their exposure route, whether it is via the respiratory route, gastronomic tract, skin or eye has an influence on their interactions.

Nanomaterials are not a homogeneous class of materials, but differ in their properties and thus in their safety properties. For example, exposure to carbon nanotubes (CNTs) has been reported to be the cause of genotoxic [6] and inflammatory effects [7–9]. The effects have been postulated to be due to their dispersal state or degree of agglomeration controlling their bioreactivity, high length, and diameter resulting in frustrated phagocytosis, structural defects, and surface functionalization, which can mitigate their inflammatory potential [10]. Generally, more adverse effects have been found with multiwalled CNTs compared to single-walled ones [11]. However, in the recent review by Bhattacharya et al. [12] on the biological interactions of carbon-based nanomaterials (CNPs) such as CNTs, graphene oxide, fullerenes, and nanodiamonds, which are potential candidates for medical applications, it was stated that more recent research on CNTs has suggested strategies to improve their biocompatibility through surface modification, such as polymer coating. The biological fate of graphene-based materials is likely to depend both on their lateral dimensions and thickness as well as on the degree of functionalization [13] as well as on layer number, stiffness, hydrophobicity, and dose [14]. Generation of reactive oxygen species (ROS) is a potential mechanism for graphene toxicity but biopersistence may also play a role. Li et al. [15] compared the effects of different carbon-based nanomaterials, fullerene (C₆₀), single-walled CNTs and multiwalled CNTs, on lung cells and concluded based on the data that C₆₀ is the least toxic of the four CNPs. Recently, some studies have reported that carbon-based nanomaterials are susceptible to biodegradation [16] by naturally occurring plant and human enzymes, peroxidases [10], with immune system playing a key role in the enzymatic digestion of these nanomaterials [17]. This cannot however be treated as entirely positive as there is also evidence that partially degraded graphene oxide or CNTs could trigger genotoxicity [18].

On the other hand, bio-based carbon nanomaterials such as cellulose nanomaterials are usually considered to be safe due to their bio-based origin and use of similar materials, such as wood powder, microcrystalline cellulose (MCC), etc., for a long time without adverse health effects. However, wood dust has been found to be a carcinogenic material [19–21] and biopersistence of long, thin high-aspect ratio fibers is a known fact, which has been also confirmed for cellulose nanofibrils [22, 23]. Biopersistent long and thin high-aspect-ratio fibers have been claimed to being potentially carcinogenic [24]. Asbestos may be the best-known example of such fibers.

Summarizing, generalization about the toxicity of carbon-based nanomaterials should be avoided as these are not single nanomaterials, but classes of nanomaterials with variable physicochemical properties, resulting in differences in their toxicological behavior. Careful engineering of nanomaterials is needed to mitigate the potential risks while preserving the useful characteristics [12]. Safe-by-design thinking should be implemented already at early stages of nanomaterial development.

It is the responsibility of the manufacturer and importer of materials and goods to ensure that the products are safe. In order to ensure the safety, they must understand the risk, which consists of hazard and exposure. According to the current view, the safety of nanomaterials, as well as of products containing nanomaterials, must be assessed case by case. Existing legislation, guidelines, and standards provide a basis for this, while published risk assessment protocols provide a tool to evaluate the hot spots and knowledge gaps in the processes involving nanomaterials. The following chapters attempt to guide the reader through the methodology on how to assess the safety of nanomaterials in industry.

2 Existing legislation, guidelines, and standards

2.1 Nanomaterial- and nanotechnology-related regulations in the EU

In 2011, the European Commission (EC) gave a recommendation on the definition of nanomaterial [25] for regulatory purposes. The recommendation defines nanomaterial as “a natural, incidental or manufactured material containing particles, in an unbound state or as an aggregate or as an agglomerate and where, for 50% or more of the particles in the number size distribution, one or more external dimensions is in the size range 1–100 nm.” At the moment, the EC nanomaterial definition is applied in various regulations in the EU, for example in regulations on Registration, Evaluation, Authorization, and Restriction of Chemicals (REACH) [26] and Classification, Labeling, and Packaging of substances and mixtures (CLP) [27], biocides, and medical devices. In EU legislation, other sector-specific definitions are also in use, partly because these regulations were adopted before the recommendation. The EC recommendation includes a requirement for a review “in the light of experience and of scientific and technological developments,” which is a continuously ongoing process. As part of the process, the Commission’s Joint Research Centre (JRC) has published a series of reports [28, 29, 30], aiming to provide scientific-technical evaluation to clarify the EC Recommendation. The evaluation concluded to propose that the origin of nanomaterials should remain unchanged, that is, meaning natural, incidental as well as manufactured nanomaterials. Because the definition is meant for regulatory purposes, the report concluded that there is little evidence to support deviation from size as the sole defining property of a nanoparticle or from the range of 1–100 nm as the definition of the nanoscale. In addition, the report concluded that some terms used in the definition are in need of clarification and that additional implementation guidance would be useful. The role of volume-specific surface area would also be worthy of clarification, and a method to prove that a material is not a nanomaterial would be helpful. In addition to the JRC reports, there are several other national and international instances that have published their opinions on the EC Recommendation. Thus, certain clarifications on the EC Recommendation are expected in the near future.

At present, nanomaterials are regulated as the corresponding bulk materials. Similarly to the producers and importers of bulk materials, the producers and importers of nano-sized materials must ensure their safety by following the current legislation, like chemicals legislation, occupational exposure-related requirements, and regulations based on the intended use, for example, whether they are to be used in food, in food contact materials (FCM), in cosmetics, etc., which may contain additional rules for nanomaterials. In the EU, the production and import of chemicals is regulated by REACH [26] and CLP [27]. In the EU, nanomaterials, as any other substances, have to be classified for hazardous properties if they show the corresponding characteristics according to the CLP. Specific groups of chemicals, such as biocides, pesticides, pharmaceuticals, or cosmetics, are covered by their own legislation. Although there are no explicit regulations for nano-s...

Table of contents

• Cover image
• Title page
• Table of Contents
• Copyright
• Contributors
• Chapter 1: Nanomaterials in industry—How to assess the safety?
• Chapter 2: Protein nanofibrils: Preparation, properties, and possible applications in industrial nanomaterials
• Chapter 3: Nanotechnology for biological photovoltaics; industrial applications of nanomaterials
• Chapter 4: The perspective of using nanocatalysts in the environmental requirements and energy needs of industry
• Chapter 5: Nanomaterials-based UV photodetectors
• Chapter 6: Industrial application of light-driven nanomaterial
• Chapter 7: Laser-driven nanomaterials and laser-enabled nanofabrication for industrial applications
• Chapter 8: Carbon nanostructures for electromagnetic shielding applications
• Chapter 9: Applications of group 15 ternary chalcohalide nanomaterials
• Chapter 10: Functionalized carbon nanomaterials for wastewater treatment
• Chapter 11: Applications of nano-biotechnology for sustainable water purification
• Chapter 12: Nano-agromaterials: Influence on plant growth and crop protection
• Chapter 13: Application of nanomaterials for removal of environmental pollution
• Chapter 14: Nanocellulose-based aerogels for industrial applications
• Chapter 15: Lignocellulosic nanomaterials for construction and building applications
• Chapter 16: Nanomaterials in nutraceutical and phytonutrient industries
• Chapter 17: Nanotechnology for pharmaceuticals
• Index