Life cycle analyses of nano-based technologies are essential to identify environmental advantages and disadvantages of nanoproducts and meet the objective of early diagnosis and treatment of environmental risks of technological developments in this area.
Nanosensors and other applications of quantum dots will be in the market soon as the transition from research to markets has been fast for many nanoproducts. Quantum dot lasers and quantum dot biodetection products have already reached markets. Given the prospective market size of quantum dots, the waste burden and environmental impacts linked to the emissions to the environment caused by the production and use of quantum dots may become signifi cant in the future. In an eff ort to identify associated risks, we used life cycle assessment software SimaPro, the LCI database Ecoinvent and other data sources to establish a LCI for the synthesis of CdSe quantum dots, which are the most frequently used quantum dots so far. Raw material use, energy use, and emissions to air, water, and soil were quantifi ed. On a mass basis, air emissions contribute the most to the cumulative emissions, followed by water emissions contributing to 12 percent of the total emissions. These emission values are specifi c for the conventional route of synthesis. Further research is required that applies Life Cycle Assessment (LCA)/LCI to raw materials selection to identify alternative raw materials that are less polluting.
Our results indicate that the isolation, purifi cation, and size selective precipitation contribute the most to environmental impacts.
Figure 37.9 Emissions to soil from the synthesis of 1 g of cadmium selenide (CdSe) quantum dots.
Zinc Sulfur Strontium Sodium Silicon Potassium Phosphorus Oils Manganese Magnesium Iron Glyphosate Fluoride Chromium VI Chloride Carbon Calcium Boron Barium Aluminum
0.01 0.1 1 10
milligrams
100 1000 10000
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Acknowledgments
This work has been supported by grant number 0646336, “Life Cycle of Nanomanufacturing Technologies” of the Division of Chemical, Bioengineering, Environmental, and Transport Systems, National Science Foundation, Cynthia Eckstein project manager.
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