- 1:40 PM

Towards a Systems View in Nanotechnology- Life Cycle Assessment of Nanoparticles Synthesis

Vikas Khanna and Bhavik R. Bakshi. Department of Chemical and Biomolecular Engineering, The Ohio State University, Koffolt Laboratories, 140W, 19th Avenue, Columbus, OH 43210

Nanotechnology is expected to play a pivotal role in influencing future global markets. Much of the research efforts in this burgeoning field focus on using the knowledge of molecular structure to synthesize novel materials with desired properties. Unfortunately, most of the developments in nanotechnology are not evaluated to quantify claims about their potential benefits via a holistic analysis of their environmental impact during their life cycle. Consequently, it is possible that the societal costs of some of the emerging technologies may outweigh the potential benefits. Researchers have identified the need for the life cycle assessment of potential nanoproducts. However, LCA of Nanotechnology poses several formidable challenges. These include the severe lack of inventory data for each step in the nanomanufacturing life cycle and about the fate, transport and impact of new nanomaterials and products. Such data are difficult to find for radically different and emerging technologies. This paper presents one of the first LCAs of nanoparticle synthesis. Life Cycle inventory data is compiled with data reported by open literature and industrial collaborators. A traditional “Cradle-to-Gate” Process LCA is performed for the synthesis of Nanoclays and Carbon Nanofibers. This approach is however not convenient as little quantifiable data is available on the human and ecosystem impact of emissions from the nanomanufacturing life cycle stages. Exergetic Life Cycle Assessment that does not rely on the impact of emissions is also performed.

These tools are used to assess the environmental life cycle burdens of Nanoclay and Carbon Nanofibers synthesis. These nanoparticles have gained a lot of attention in recent years because of their applications in a wide array of industries. One of these applications is the manufacture of nanocomposites. Nanocomposites are a new class of composites that have a dispersed phase with atleast one ultrafine dimension, typically a few nanometers. The reinforcing phase in nanocomposites can be comprised of nanoclays, nanofibers, Single-Walled Carbon Nanotubes (SWCNT's) or Multi-Walled Carbon Nanotubes (MWCNT's). Polymer Nanocomposites can improve mechanical reinforcement, high temperature durability, enhanced barrier properties and reduced flammability. Although use of nanoparticles in various applications seems like a promising solution to achieve enhanced material properties, there are still several issues that need to be addressed for confirming their “benign nature”. It is critical to collect environmental, health data before encouraging the widespread use of products based on these nanoparticles as well as perform their Life Cycle Assessment to study the environmental impacts throughout a product's broader life cycle to ensure that the environmental impact is not just being shifted to other stages of the life cycle. In this paper, Nanoclay synthesis from Montmorillonites is considered as the first example. In the second example, catalytic pyrolysis of hydrocarbons on metallic catalyst to produce Carbon Nanofibers is studied. A “cradle-to-Gate” LCA was performed for these two kind of nanoparticles. The various steps in the life cycle along with the LCA results for the two types of nanoparticles will be described. In addition, steps in the life cycle with the maximum environmental burden will be described. Current work is in progress to integrate the fate and transport of these nanomaterials with the life cycle results to get an insight into the ecotoxicity of these nanomatertials. A thermodynamic LCA is also underway to get a preliminary insight into the ecotoxicity of these nanoparticles.