Comparative life cycle assessment of silver nanoparticle synthesis routes

Abstract

Silver nanoparticles (AgNPs) can be produced through a variety of synthesis routes with differing mechanisms, inputs, yields, reaction conditions, and resulting size distributions. Recent work has focused on applying green chemistry and sustainable manufacturing principles to nanomaterial synthesis, with the goal of reducing life cycle energy use and environmental impacts. Life cycle assessment (LCA) is used here to analyze and compare the environmental impacts of AgNPs produced through seven different synthesis routes (cradle-to-gate). LCA reveals both direct and indirect or upstream impacts associated with AgNPs.Synthesis routes were chosen to represent current trends in nanoparticle synthesis and include physical, chemical and bio-based methods of production. Results show that, across synthesis routes, impacts associated with the upstream production of bulk silver itself were dominant for nearly every category of environmental impact, contributing to over 90% of life cycle burdens in some cases. Flame spray methods were shown to have the highest impacts while chemical reduction methods were generally preferred when AgNPs were compared on a mass basis. The bio-based chemical reduction route was found to have important tradeoffs in ozone depletion potential and ecotoxicity. Rescaling results by the size-dependent antimicrobial efficacy that reflects the actual function of AgNPs in most products provided a performancebased comparison and changed the rank order of preference in every impact category. Comparative results were also presented in the context of a nanosilver-doped wound dressing, showing that the overall environmental burdens of the product were highly sensitive to the synthesis route by which the AgNPs are produced.Environ. Sci.: Nano This journal is † Electronic supplementary information (ESI) available. See Nanoparticle synthesis has been found in several life cycle assessments (LCAs) of AgNP-containing products to be a large contributor of environmental impacts. Impacts are highly dependent on the synthesis route, yet several routes lack LCA data and/or results. Here we conduct and compare LCAs for all industrially important synthesis routes and identify critical inputs and synthesis steps, informing future process improvements. Impacts from the production of bulk silver were dominant for nearly every impact category, but with different patterns among routes. Results are presented on a mass basis as well as by antimicrobial efficiency, a novel approach. This work provides a transparent and general basis for the research community to model nano life cycle impacts in subsequent assessments of AgNP-enabled products.

Metal Nanoparticles in Surface Waters – a Risk to Aquatic Organisms

“…The migrations and behaviour of these pollutants can pose environmental and human risks [10], [13][14][15] This has provoked discussions about the safety of, and potential risks associated with, nanotechnology. A strong emphasis has been placed on determining the toxicity of nanostructures to various groups of organisms, including perennials, wheat, bacteria, protozoa, macrophytes, earthworms, fish, mice and rats [16][17][18][19][20][21][22][23][24][25].…”

“…Losy i zachowanie się tych zanieczyszczeń mogą stanowić potencjalne zagrożenie dla środowiska oraz człowieka [10], [13][14][15].…”

Nanosilver‐Enabled Food Storage Container Tradeoffs: Environmental Impacts Versus Food Savings Benefit, Informed by Literature

“…Life cycle assessment (LCA) is a systematic tool for determining the environmental effects of a product or process throughout its lifetime (Curran ). Recently, LCA has been applied to nano‐enabled products, and in particular nAg‐enabled products, to determine their tradeoffs compared with conventional products, including nAg‐enabled products such as bandages (Pourzahedi and Eckelman , ), textiles (Meyer et al ; Walser et al ; Hicks et al ; Hicks and Theis ; Hicks et al ; Hicks ), and food storage containers (Westerband and Hicks ). The environmental effects of nAg‐enabled food storage containers have been modeled previously by the authors (Figure ), with the major finding that most of the environmental effects of a food storage container are not related to the Ag (Westerband and Hicks ).…”

Energy Efficiency and Scalability of Metallic Nanoparticle Production Using Arc/Spark Discharge

“…Figure 1 shows the basic function scheme for a NP production unit consisting of an evaporation reactor, a power supply and a NP collection filter. produced using these routes have been compared by Pourzahedi and Eckelman [10]. They found that chemical reduction routes for NP production of silver have the lowest environmental impact while arc plasma and flame spray pyrolysis have the second highest and highest environmental impacts, respectively.…”

“…Other processes for metallic NP production include chemical reduction methods, electrochemical methods, flame spray pyrolysis, vapour deposition and ablation and sputtering methods [8,9]. The environmental impact of silver NPs for example, produced using these routes have been compared by Pourzahedi and Eckelman [10]. They found that chemical reduction routes for NP production of silver have the lowest environmental impact while arc plasma and flame spray pyrolysis have the second highest and highest environmental impacts, respectively.…”