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Exploring Nanogeosciences: Analytical Tools & Concepts

Discover the world of nanogeosciences through various analytical techniques, from electron microscopy to light scattering, and explore the occurrence, characteristics, and role of natural nanoparticles in environmental processes. Learn about the formation, transformation, and applications of nanoparticles to address environmental challenges.

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Exploring Nanogeosciences: Analytical Tools & Concepts

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  1. vd Kammer Montano Laycock Gondikas Praetorius Navratilova

  2. Nanoparticles in the Environment: Alwayshavebeenthere, in large amounts Source: amazonmillennium Source: Sanibel-CaptivaConservationFoundation • NANOGEOSCIENCES • nanoscale phenomena in (hydro-)geological systems • occurrence & characteristics of natural nanoparticles • interactions and role in natural processes • formation & transformation • application of nanoparticles to solve environmental problems

  3. TXM TEM Wet-SEM SEM AFM DLS …toexploretheworldofnanogeosciencesweneedreliableanalyticaltoolsandconcepts XPS Fl-FFF CIS LIBD/LIBS SAXS

  4. . NP } } ∆ 108 m ∆ 108 m Mike Hochella, Virginia Tech.

  5. …the beginning we were concerned about size and how to determine it • techniques: • electron microscopy • atomic force microscopy • light scattering • tracking analysis • field flow fractionation

  6. …later we were concerned about size and how to determine it we were concerned about distributions, agglomerates, dissolution

  7. …then we were concerned about size and how to determine it we were concerned about distributions, agglomerates, dissolution we were concerned about the natural background

  8. …today we still are concerned about size and how to determine it we still are concerned about distributions, agglomerates, dissolution we still are concerned about the natural background we are concerned about transformations

  9. we need handles to distinguish nanoparticles Engineered NPs Natural and Engineered NPs • AuNPs practically no background • AgNPslow to no background but speciation • fullerenes  specific structure, but background • CNTs  shape analysis • CuO-NPs  medium background • ZnO-NPs  medium background • SiO2-NPs   • TiO2-NPs  • CeO2-NPs   • FeOx-NPs   • organic NPs   • have all high particulate background    in the lab in naturalwaters in soils & sediments

  10. Bulk Elemental Ratios • Natural elemental ratios show a trend with a natural variation • Statistically significant deviations outside confidence interval of trend may be presence of engineered nanomaterials • May require significant amounts of engineered nanomaterial • Limited information about physical/chemical state of nanomaterials (i.e. aggregation) Montaño, M. et al. Environmental Chemistry, 2014

  11. single particle analysis • selective & specific counting techniques • elemental composition & morphology (EM) • single element derived particle size (spICPMS) • time resolved spICPMS • quadrupole instruments • only single isotope monitored • fast scan quadrupole • 2 isotopes can be monitored (limitations) • Time of Flight instruments: • multiple isotope monitoring

  12. Principle of ICP-MS single particle analysis on non-C particles To plasma Fewdissolvedatoms Signal Signal createdis not distinguishedfrom randombackgroundnoise (<LOD) To plasma Same amountofatoms but clustered in nanoparticles Discontinuityofmassdistribution Signal results in detectable signal spikes from single particles singlemeasurement (dwell time) lastsonly 0.1 – 10 ms ~ 100 – 10,000 datapoints per second v.d. Kammer et al. ET&C 2012

  13. TiO2 Field Exampleusing Element Ratios: TiO2Nanoparticle Release fromSunscreens TiO2 TiO2 WASH OFF ? air/water interface ? ? large aggregates Typically coated with AlOx layer and organic materials suspended matter ? sediment Gondikas et al. (2014) ES&T 48, 5415-5422

  14. Gondikas et al. (2014) ES&T 48, 5415-5422 summer fall/winter spring spring fall/winter summer

  15. Attachment to Air/Water Interface collection of hydrophobic layer by attachment to glass & cellulose acetate membranes Ti/Al > 0.146 Ti at surface Results indicate short residence time on the air/water interface, possibly strong dependence on weather conditions Gondikas et al. (2014) ES&T 48, 5415-5422

  16. Sediment Core Samples • Temporalandspatialdistribution of Ti/Al ratios in sediment • elevated Ti/Al elemental ratios in younger sediments • 25 cm depth equals 1995  ~ 1 – 1,25 cm/year • Bulk analysis does show difference in Al/Ti ratio if concentration is high enough sediment core sampling ~ 2005 ~ 2000 1995 Gondikas et al. (2014) ES&T 48, 5415-5422

  17. Example were element ratios do not help: CeO2nanoparticles in soils; sp (TOF) MS)(used as catalyst, abrasive or polishing material, fuel additive)

  18. StrategyforIdentification: Trace Elements in Natural Colloids • naturalbackground 10 – 100 ppm in soils • naturalbackgroundcomeswith La, Nd, Thandotherimpurities soils & sediments: ratioCeto La ~ 2:1 10 nm Cecontainingnanoparticlefrom Clark Fork River banksediment(Plathe et al.; EnvChem 2010)

  19. CeO2 NP analysis in soilmatrix – bulkanalysis FFF-ICPMS in colloidalextracts CeO2recoveriesare 16% in the 4 ppm spike 24% in the 40 ppm spike 34% in the 400 ppm spike bckgr. 74 ppm +400 ppm +40 ppm +4 ppm Ce/La ratioworks in bulkanalysisfrom 25% ofthebackgroundconcentration  unrealisticscenario: bulkanalysisdoes not work

  20. spICP-TOF-MS Case Study: CeO2 NP in soils Single-element single-particle ICP-MS of colloidal extracts spICP-MS can only monitor one element at a time (potentially two with quadrupole switching)  Cannot differentiate between Ce-only particles (ENPs) and particles containing Ce+La (NNPs) Praetorius, A.; et al.; Environmental Science: Nano, 2017

  21. ICP-time-of-flight-Mass Spectrometry • ICP-TOF-MS detects all elements quasi-simultaneously • A full mass spectrum is collected every extraction (dwell) time (46μs) • Could be used to examine elemental ratios on a particle-by-particle basis Hendriks, L. et al. Journal of Analytical Atomic Spectroscopy, 2017 Montaño, M. et al., 2017

  22. sp-ICP-TOF-MS: A door opener to study particles in the environment • Developing single particle ICP-time-of-flight-MS for the analysis of engineered nanoparticles in environmental systems • Using advanced nanometrology to study naturally occurring nanoparticles and nanogeochemical processes Manuel Montano

  23. CeO2 NP analysis in soilmatrix – sp-ICP-TOF-MS Multi-element single-particle ICP-TOF-MS of colloidal extracts natural NP • ICP-TOF-MS • 300 ms time resolution • SPK3 • 0.4 mg kg-1 CeO2 added • 0.5% of background • improvements possible engineered CeO2 NP

  24. spICP-TOFMS sorts pure from dirty particles time resolution 30 – 50 µs massresolution 3000 – 6000 sensitivity ~ q-pol ICPMS Natural Ce-containingnanoparticles time resolved massresolved

  25. Multi-element spICP-TOF-MS – machine learning for identifiaction • Machine Learning • Supervisedgradientdecisiontreeboostingclassification (GBC) machinelearningmodel • Identificationofelementalfingerprints • 27 elementsconsidered • 17 selectedforclassification

  26. CeO2 NPs analysis in soil matrix – data analysis 0 x0.0006 x0.006 x0.06 x0.6 x6 concentration factor ENP to background

  27. some applications of TOF MS: Pt isotopes • Time-of-flight also enables isotopic quantification on a per-particle basis • Accuracy of isotopic quantification may be useful for isotopically enriched particles; not for isotopic enrichment studies

  28. sp-ICP-MS sp-ICP-TOF-MS applications continued: Ag/Au core shell particles • Analysis of mixtures of Au, Ag, and Au/Ag core-shell NPs • Quadrupole can only capture single-element signals • ICP-TOF-MS can confidently identify single and multiple element particles

  29. applications continued: natural particles in surface water • Useful for screening natural environments for naturally occurring nanoparticles • Sampling campaign of surface waters shows potential for understanding nanogeochemical environment

  30. applications continued: As bound to Fe-nanoparticles • Soil collected from Lojane, Lipkovo, Republic of Macedonia • Cadmium and antimony mine • Extraction of nanoparticles (sonochemical with 1% FL-70) shows arsenic bound to iron colloids Tasev et al. SGEM 2017, Vol. 17, 2017 Montaño, M. et al., Unpublished data. 2018

  31. a few thoughts to take home… • many processes in natural environments are dominated by nano-processes. We need the right tools to investigate them • element ratios/fingerprints (including isotopes etc.) might be very helpful to distinguish nanoparticles in the environment • multi-element sp-ICP-TOF-MS might be a door-opener in some cases, can be nicely combined with AI tools • sp-ICP-TOF-MS is still at its infancy, sensitivity needs to be increased, many things to be optimized and learned • as a decade ago, the smart combination of several/hyphenated techniques might be the golden rule

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