The role of Nanotechnology in Chemical Substitution
Ulrich Fiedeler, Miklos Gyorffi
ITAS; Policy Department A: Economic and Scientific Policy, DG Internal Policies
Abstract
OBJECTIVE This project is one of ten projects the Scientific Technology Option Assessment (STOA) panel has initiated this year. The project is called: The role of Nanotechnology in Chemical Substitution . The aim of the project is to give an overview of already used and conceivable applications of Nanotechnology (NT) in order to replace hazardous chemicals. The overall idea behind this project is to identify new applications of NT which could help to reduce the risks related to hazardous substan...Moreces and chemical processes. One prominent example is the substitution of anti-fouling coatings used in the ship industry by nanotechnological based coatings, which are already under investigation (AMBIO-project, http://www.ambio.bham.ac.uk/). BACKGROUND The project is focused on the identification of concepts or ideas for substitution in the field of NT. The assessment of the hazardous potential of the nanotechnological substitute itself IS NOT OBJECTIVE OF THIS STUDY, NOR IS THE EVALUATION OF THE FEASIBILITY AND EFFICIENCY OF THE concepts for substitution. Related to the objective of this study three questions have to be addressed at the beginning of the project: 1. Which substances are considered as hazardous chemicals Since this project is focused on determining the potential of NT, the issue of how a substance can be identified as hazardous is discussed only briefly. Nevertheless, to estimate the potential of substitution it must be clear what is to be substituted. Here, a pragmatic solution is chosen. Only substances which are already known as toxic and dangerous to humans and the environment are considered. This is presented in section 4.3. 2. What is meant by the term Nanotechnology and how can it be distinguished from biology and chemistry respectively There is no clear definition of NT nor is it possible to assign precisely an application to NT or to chemistry or to biology (see section 3). The term NT implies a great variety of different techniques, analytic tools and materials including their production. Nevertheless, to identify relevant applications of NT serving the aim of this project presupposes a certain concept of NT. The first approach used for this study is that everything is considered as NT what is claimed by proponents to be NT. In detail this means that all publications, which are published in journals carrying Nano in their title (e.g. Journal of Nanoparticles Research ), and all projects carrying Nano in their title are considered to belong to NT. Publications and projects dealing with typical NT objects such as fullerenes or nanotubes are also attributed to NT even if Nano is not the headline. This is a pragmatic solution to start with. The question of whether a certain technical concept of substitution can be attributed to NT could not be explicitly discussed within the scope of this project. For all presented examples the assignment to NT was accepted by the experts during the validation workshop. Furthermore, the relation of the presented examples of substitution to NT and the connection to other disciplines is described in one or two sentences for each case or field of substitution presented in section 7. In this respect it is important to mention that the term NT has also a political dimension. In the all over competition on funding of research the assignment of benefits and useful applications to a certain discipline is crucial (see section 3.1 and 3.4). 3. What is the meaning of chemical substitution in relation to NT The original meaning of chemical substitution is quite clear and narrow: one chemical substance is replaced by another, for whatever reason (availability, costs, technical requirements). Due to the fact that NT is neither a group of substances nor a group of products but an enabling technology the way NT can provide solutions is more fundamental than just replacing the function of the substitute. It is assumed that NT provides new effects which are not based on chemical properties of the related material but on the physical properties caused by its size and shape. It can be used to develop completely different processes or different products which serve the same purpose but in a completely different way. Therefore in this report substitution is not restricted to the replacement of a hazardous substance by a less or non-hazardous substance. In this project this broader meaning of substitution is applied as it is in the chemical context. The interviews and the comments of the experts during the validation workshop have shown that it is a delicate but necessary challenge to broaden the meaning of the term substitution without loosing its focus. METHOD Since most NTs are at an early stage of development and due to the fact that NT is an enabling technology there are only a few publications and only very few research projects directly addressing the substitution of hazardous substances by NT. Therefore, the challenge of this project was to estimate a potential that has not yet been explored. The research for the findings is based on two approaches: A literature research and interviews with experts. The relevant literature was identified by the following criteria: Reports from governmental departments, research institutes, industrial associations, and other stakeholder groups which addresses NT and environmental issues. Journals, carrying Nano in their titles. Certain journals in the field of applied chemistry. Journals addressing chemistry and environmental issues (e.g. Green Chemistry) broad keyword based searches in several data bases This keyword based search was performed in journals of the American Chemical Society (ACS) journals covered by Science Direct The considered journals are listed in appendix 10.5. The experts for the interviews were chosen due to publications on NT related to environmental issues or even related to a case of substitution. They are all experts in the field of NT but with different backgrounds. The experts include representatives from industry, science, research management, and NGOs. Experts who were contacted are listed in appendix 10.6. To validate the findings of the project nine experts from different fields of NT or chemistry with nanotechnological background were invited to a workshop at the European Parliament. Prior to the workshop a summary of the preliminary results of the project was sent to the experts. The workshop focused on the discussion among the experts but was open to Members of the European Parliament in order to give them the opportunity to give their views in the evaluation of the preliminary findings and related policy options. In addition the workshop was open to other persons active in the field of nanotechnology. The list of invited experts can be found in appendix 10.1.1. The results of the workshop are summarised in appendix 10.1.2 to 10.1.4. FINDINGS The findings can be subdivided into seven categories. COATINGS Most examples are to be found in the field of surface treatments like coatings, paints, and texturing surface. Example: Self cleaning surfaces Reduction of adhesion is relevant for many applications. For example is the reduction of adhesion one approach to substitute antifouling agents like TBT. In addition the use of cleaning agents could be reduced or even made superfluous. If these coatings are used to cover cladding it is assumed that the use of paint will reduce considerably. FLAME RETARDANTS There are several approaches to replace bromine flame retardants with products using NT. Bromine is used as a reaction inhibitant by absorbing oxygen. A similar effect could be realised by nanoparticles. If TiO2, SiO2, MgO, or ZnO nanoparticles are added to substances oxygen is accumulated and builds up an oxide layer. FLEXIBILISER Flexibiliser leads to elastic bindings between the polymer chains. It is known from tires that the addition of nanoparticles can enhance the flexibility of the rubber mixture. A similar effect is conceivable with plastics. SUBSTITUTION OR REDUCTION OF SOLVENTS Organic solvents or volatile organic compounds (VOC) in general are one group of chemicals which are often toxic, bio-accumulative and, due to their volatility, difficult to control. Solvents can not be directly substituted by NT. But in the literature it is often mentioned that NT may change processes in a way that in some cases solvents can be reduced or will even become dispensable in future. CATALYSTS Research on catalysts is an old and vast research field. In this field, the distinction between pure chemistry and nanotechnology is especially difficult. Research in this field was already in the dimension of nanometers, therefore it is not clear to which extent further developments may be attributed to NT. The development of new catalysts is seldom directly aimed at substituting hazardous substances. Instead, in the development of new catalysts several objectives are pursued at the same time. Therefore, substitution of hazardous substances in this field is often very indirect. The effect of catalysts on human health and the environment, if they are released, could be detrimental. Their benefits and risks have to be balanced in detail. A very well investigated example of a case of substitution is styrol synthesis where it was possible to reduce the by-production of heavy metals due to NT catalysts. OTHER EXAMPLES: DRUG TARGETING Within NT there exist several attempts to improve the efficiency of pharmaceuticals by bringing them directly to the cells where they are needed. Of course, the main goal is to reduce the side effects of the therapy, hence making the therapy more tolerable and effective. But especially chemotherapeutics are detrimental for the environment and the release of antibiotics causes severe problems due to resistance of bacteria. REMEDIATION A lot of the literature concerning nanotechnology and environmental issues deals with the potential of NT for cleaning up polluted air, water, and soil. Most of the research activities concerning the development and use of catalysts in respect to hazardous substances are not in order to avoid them but to decompose them after they have been released into the environment. These examples are not within the scope of the project. Nevertheless, it should be mentioned that most articles on environmental benefits attributed to NT are of this nature. CONCLUSIONS The investigations of this project show that the focus of this study is unique. Nevertheless, considering the findings it can be concluded that at present times NT can not contribute in an exceptional manner to a large increase of substitution of hazardous substances. Instead it revealed that the contribution of NT with respect to the reduction of hazardous substances is manifold but incremental. However, most of the interviewed or invited experts assign NT a considerable potential for substitution for the future. For a comprehensive assessment of this potential, each identified example has to be assessed case by case and in more detail as it was performed in this project. This assessment has to start with following questions: 1. Of what importance is the example under consideration 2. Are there other chemicals which could substitute the substance in question 3. Of what quality (feasibility, efficiency) is the suggested NT To evaluate the benefit of the new nanomaterial in relation to the conventional one a life cycle assessment (LCA) has to be performed. This kind of detailed assessment is only useful if there are some signs related to a special case of possible substitution suggesting that is worth evaluating this special case in detail. One of those cases is biocide coatings on the basis of silver nanoparticles. The last conclusion deals with the methodological challenges of the exploitation of unknown fields of application of NT for substitution. How is it possible to find a connection in a systematic way between a hazardous substance and a particular NT which could facilitate the substitution of this substance A first step in this direction is the systematisation the functions NT can provide. These functionalities could be compared with the functionalities hazardous chemical substances provide. Thus the question of which hazardous substances could be substituted by which NT is reduced to the question of which functionality of the hazardous substance could be provided by which NT.
keywords:purposes; Options; FINDINGS; Technology Assessment; hazardous substances; EUROPEAN PARLIAMENT; Flame retardants; role of Nanotechnology; Chemical Substitution; IP STOA/ST; definition of NT; Self cleaning; Biocide coatings; Flexibiliser; Substitution or reduction
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