Precious metal recovery from nanowaste for sustainable nanotechnology: Current challenges and life cycle considerations Dr. Peter Vikesland Dr. Sean McGinnis Paramjeet Pati pvikes@vt.edu smcginn@vt.edu param@vt.edu SUN-SNO-GUIDENANO Conference 2015
Background | Research Gap | Method | Life Cycle Assessment | Results | Conclusions sodium ‘Synthetic’ hydrazine Chemicals borohydride grape pomace cypress leaves cinnamon Green s Chemicals o y b e a coriander leaves n
Background | Research Gap | Method | Life Cycle Assessment | Results | Conclusions 1.0 Error bars represent 95% confidence interval Cumulative Energy Demand (MJ) Uncertainty results from 0.8 gold salt model and energy use 0.6 0.4 0.2 0.0 borohydride citrate hydrazine soybean seed sugarbeet pulp
Background | Research Gap | Method | Life Cycle Assessment | Results | Conclusions 6 Strong reducing agents (100% yield assumed) Reported yields Cumulative Energy Demand (MJ) 5 100% yield (assumed) 75% yield (assumed) 50% yield (assumed) 4 From a life cycle perspective, gold NP synthesis using 3 bio-based (“green” ) reducing agents can have substantial environmental impacts. 2 1 0 borohydride cypress leaf extract C. camphora soybean seed C.album extract sugarbeet pulp soybean seed extract grape pomace citrate hydrazine vitamin B cinnamon ginseng mushroom D-glucose coriander “Life Cycle Assessment of “Green” Nanoparticle Synthesis Methods”, Environmental Engineering Science (2014) . Paramjeet Pati, Sean McGinnis and Peter J. Vikesland.
Background | Research Gap | Method | Life Cycle Assessment | Results | Conclusions If gold is the key driver of life cycle impacts, can we reduce impacts by recovering/recycling gold? The embodied energy of gold drives most of the life cycle impacts of gold nanoparticle 1 mg Gold NPs synthesis. Sodium Tap Cleaning Gold Deionized Heating Stirring Citrate Salt Water Solvent Water Citric Sodium Electrical Gold HCl HNO 3 Chlorine Acid Carbonate Energy (Red ‘flow’ lines show the energy associated with each input. Thicker lines imply higher energy inputs.)
Background | Research Gap | Method | Life Cycle Assessment | Results | Conclusions
Background | Research Gap | Method | Life Cycle Assessment | Results | Conclusions Recovering gold from nanowaste … … using α -cyclodextrin - AuBr 4 + K(OH 2 ) 6 http://unam.bilkent.edu.tr Hydrogen - AuBr 4 bonding
Background | Research Gap | Method | Life Cycle Assessment | Results | Conclusions “Selective isolation of gold facilitated by second-sphere coordination with α -cyclodextrin ” . Nature Communications, Liu et al. (2013)
Background | Research Gap | Method | Life Cycle Assessment | Results | Conclusions Dissolution in Precipitation HBr/HNO 3 Selective recovery of Gold nanowaste gold using α -cyclodextrin Filtration Schematic of gold recycling experiments Sonication Precipitation of gold (Resuspension) using Na 2 S 2 O 5 HCl/HNO 3 Reduction HAuCl 4 solution Gold nanoparticles
Background | Research Gap | Method | Life Cycle Assessment | Results | Conclusions Powder XRD
Background | Research Gap | Method | Life Cycle Assessment | Results | Conclusions 2 UV-vis 1,5 Absorbance 1 HAuCl 4 solution 0,5 0 250 300 350 400 450 500 550 600 Wavelength (nm) Stock_HAuCl4 Recycled_HAuCl4
Background | Research Gap | Method | Life Cycle Assessment | Results | Conclusions Calculated d-spacing d-spacing (Å) for gold (Å) 1.25, 1.19 1.23, 1.18 Gold nanoparticles 1.46 1.44 2.06 2.04 2.39 2.36 Diffraction
Background | Research Gap | Method | Life Cycle Assessment | Results | Conclusions Can we recover gold from nanowaste? Yes, we can. (But should we?)
Background | Research Gap | Method | Life Cycle Assessment | Results | Conclusions HAuCl 4 Gold HNO 3 1 mg Other Aqua AuNP regia chemicals HCl Citrate DI water Electricity Water Synthesis Cleaning Cooling Stirring Heating water water
Background | Research Gap | Method | Life Cycle Assessment | Results | Conclusions Dissolution in Precipitation HBr/HNO 3 Selective recovery of Gold nanowaste gold using α -cyclodextrin Filtration Sonication Precipitation of gold (Resuspension) using Na 2 S 2 O 5 HCl/HNO 3 Reduction HAuCl 4 solution Gold nanoparticles
Background | Research Gap | Method | Life Cycle Assessment | Results | Conclusions HBr Dissolution in HBr/HNO 3 HNO 3 Recycle α -CD Gold-CD complex 1 mg Precipitate AuNP HAuCl 4 from Precipitate recovered & resuspend gold the complex NaCl Recover Electricity gold HNO 3 HCl precipitate To waste Heating treatment NaHSO 5
Background | Research Gap | Method | Life Cycle Assessment | Results | Conclusions Synthesis Recycling
Background | Research Gap | Method | Life Cycle Assessment | Results | Conclusions Synthesis Recycling Actual LCA model for 90% recycle scenario
Background | Research Gap | Method | Life Cycle Assessment | Results | Conclusions Note: 10% recycle means: 10% of the gold nanowaste is recovered and re used for gold nanoparticle synthesis. The rest 90% gold is not recovered , and goes into waste disposal. 10% 50% 90% Dispose all recycle recycle recycle gold as waste
Background | Research Gap | Method | Life Cycle Assessment | Results | Conclusions Error bars represent 95% confidence intervals 10% 50% 90% Dispose all recycle recycle recycle gold as waste
Background | Research Gap | Method | Life Cycle Assessment | Results | Conclusions WRONG! Hmm.. overlapping error You have bars… means the difference correlated isn’t statistically significant, uncertainties! right? Makes no difference whether we recycle or not…
Background | Research Gap | Method | Life Cycle Assessment | Results | Conclusions Correlated uncertainties in LCA: An example Comparing 1 kg of product A vs. 1 kg of Product B: Product A Product B Aluminium 1 kg 0.8 kg Cast iron 1 kg 0.8 kg Polystyrene 1 kg 0.8 kg (Product B uses 20% less inputs compared to Product A. There are no extra, hidden inputs in products A and B) Q: Which of the two has a lower environmental impact? a) Product A b) Product B c) It depends d) Is this a trick question?
Background | Research Gap | Method | Life Cycle Assessment | Results | Conclusions Q: Which of the two has a lower environmental impact? a) Product A b) Product B c) It depends d) Is this a trick question? The key here: correlated uncertainties . All three inputs (aluminium, cast iron and polystyrene) have uncertainties that are common to both Product A and Product B.
Background | Research Gap | Method | Life Cycle Assessment | Results | Conclusions
Background | Research Gap | Method | Life Cycle Assessment | Results | Conclusions Metal depletion
Background | Research Gap | Method | Life Cycle Assessment | Results | Conclusions Metal depletion Freshwater ecotoxicity Climate change
Background | Research Gap | Method | Life Cycle Assessment | Results | Conclusions Fossil depletion Metal depletion Water depletion Natural land transformation Urban land occupation Agricultural land occupation Ionizing radiation Marine ecotoxicity Freshwater ecotoxicity Terrestrial ecotoxicity Particulate matter formation Photochemical oxidant formation Marine eutrophication Human toxicity Freshwater eutrophication Terrestrial acidification Ozone depletion Climate change
Background | Research Gap | Method | Life Cycle Assessment | Results | Conclusions Metal depletion 10% 50% 90% Dispose all recycle recycle recycle gold as waste
Background | Research Gap | Method | Life Cycle Assessment | Results | Conclusions Metal depletion
Background | Research Gap | Method | Life Cycle Assessment | Results | Conclusions Fossil depletion Metal depletion Water depletion Natural land transformation Urban land occupation Agricultural land occupation Ionizing radiation Marine ecotoxicity Freshwater ecotoxicity Terrestrial ecotoxicity Particulate matter formation Photochemical oxidant formation Human toxicity Marine eutrophication Freshwater eutrophication Terrestrial acidification Ozone depletion Climate change
Background | Research Gap | Method | Life Cycle Assessment | Results | Conclusions Fossil depletion Metal depletion Water depletion Natural land transformation Urban land occupation Agricultural land occupation Ionizing radiation Marine ecotoxicity Freshwater ecotoxicity Terrestrial ecotoxicity Particulate matter formation Photochemical oxidant formation Human toxicity Marine eutrophication Freshwater eutrophication Terrestrial acidification Ozone depletion Climate change
Background | Research Gap | Method | Life Cycle Assessment | Results | Conclusions Fossil depletion Metal depletion Water depletion Natural land transformation Urban land occupation Agricultural land occupation Ionizing radiation Marine ecotoxicity Freshwater ecotoxicity Terrestrial ecotoxicity Particulate matter formation Photochemical oxidant formation Human toxicity Marine eutrophication Freshwater eutrophication Terrestrial acidification Ozone depletion Climate change
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