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Characterization of dissolved metals and metallic nanoparticles in asphaltene solutions by Single Particle ICP-MS Jenny Nelson, Michiko Yamanaka, Francisco A Lopez-Linares, Laura Poirier, and Estrella Rogel Energy Fuels, Just Accepted Manuscript • DOI: 10.1021/acs.energyfuels.7b02380 • Publication Date (Web): 13 Oct 2017 Downloaded from http://pubs.acs.org on October 14, 2017

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Characterization of dissolved metals and metallic nanoparticles in asphaltene solutions by Single Particle ICP-MS Jenny Nelson,1 Michiko Yamanaka,2 Francisco Lopez-Linares,3 Laura Poirier,3 Estrella Rogel3 1

Agilent Technologies, Santa Clara, CA 95051, USA 2

3

Agilent Technologies, Tokyo, Japan

Chevron Energy Technology Company, Richmond, CA 94597, USA

ABSTRACT Even though evaluating the metal content in asphaltenes is now a routine analysis, determining the nature of the metals present in asphaltenes has continued to be an elusive subject. In this work, we presented for the first time, the application of single particle inductively coupled plasma mass spectrometry (spICP-MS) in hydrocarbon media to determine the presence of metal-containing nanoparticles in asphaltene solutions. This method also offers the unique ability to differentiate between metal-containing nanoparticles and dissolved metals. The study of three asphaltene samples from different origins indicates that vanadium and nickel are entirely dissolved probably as part of soluble coordination complexes such as porphyrins. In clear contrast, we found that molybdenum and iron are forming part of nanoparticles and we report nanoparticle distributions. We found that nanoparticle distributions for molybdenum are very similar for the different asphaltenes, while for iron oxide the size increases as the content of this metal in the sample increases. Relative concentrations of these metals in nanoparticles indicates most of the molybdenum is present as soluble compounds in the organic medium, while the iron is predominantly forming nanoparticles. This study demonstrates the applicability of spICP-MS

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in hydrocarbon media as a potential and routine technique to characterize metals in asphaltenes, crude oils, and petroleum-derived materials.


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INTRODUCTION One of the challenges in the refining of heavy fractions is the handling of metals, as they are deleterious to several operations in refineries. Metals can poison catalysts, induce corrosion, accumulate in processing units and, if passing into fuel products, they can damage the moving parts of engines.1 Therefore, to understand the origin and nature of trace element species in crude oils and bitumens is of a substantial practical interest. Among the metals present in crude oils, vanadium and nickel are the most intensely studied since they are found in the largest concentrations. The forms in which vanadium and nickel occur in the crude oil have been the focus of intense debate since almost one century ago.2 There is a consensus that vanadium and nickel exist in the form of coordination complexes compounds as porphyrins3 and several porphyrinic structures have been identified.4-5 However, substantial evidence for non-porphyrin compounds has also been reported.6-7 Metal complexes containing nickel and vanadium may occur as free molecules,8-9 or as assimilated subunits in asphaltene aggregates10 either by noncovalent interactions,11 trapping inside the nanostructures12-13 or forming part of larger macromolecules within the aggregates.3,14 Other metals present in asphaltenes might also form transition metal complexes or be present as inclusions,15 but they have not been studied as extensively as vanadium and nickel. Two of those elements that naturally occur in crude oils in trace amounts are iron and molybdenum. Although a significant amount of research has been done regarding the interaction between iron16-18 or molybdenum19-20 containing materials and petroleum, very little information is available about the nature of the iron or molybdenum components in crude oil21-23 It is well known that metals accumulate in heavy fractions, particularly, in asphaltenes. In the present work, we explore the nature of vanadium, nickel, iron, and molybdenum in asphaltenes


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using single particle inductively coupled plasma mass spectrometry (spICP-MS). This recently developed technique has shown great potential in the analysis of nanoparticles (NP), mainly in aqueous media, in complex matrices such as food, consumer products, and biological tissues.24 spICP-MS is used to record the target element signals generated from individual NPs in the solution analyzed, allowing simultaneous determination of the number, concentration, and size of particles present, as well as the dissolved element concentration. This approach has been developed independently by several researchers,25-28 and modern ICP-MS instruments can now offer automated acquisition and calibration approaches to support NP characterization. The principle to determine concentration and size of particles is very simple: the signal induced by the ionization of a nanoparticle in the plasma torch produces a flash of ions that can be measured by the mass spectrometer. The intensity of the signal for the matrix elements is proportional to the size of the particles and the mass fraction of the analyte element within the particle. The frequency of the signals is directly proportional to the number concentration of the nanoparticles in the solvent. Current ICP-MS system can use shorter dwell times (below 1 ms) and can acquire data continuously with no settling time between measurements.25 This feature gives the opportunity to make several measurements within one particle event, allowing integration of the signal from a single NP and significantly reducing the chance of overlapping signals from multiple particles. There are many challenges in measuring NPs accurately by ICP-MS, particularly the ability to distinguish the background signal from the signal generated from a small particle. Consequently, it is not surprising that much of the work reported thus far has concentrated on elements such as silver and gold, which are relatively easy to measure by ICP-MS. Natural


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samples such as asphaltenes contain elements that are harder to evaluate and additionally, they present challenges that are unique to non-aqueous systems. In the present work, we introduce the use for a first time, sp-ICP-MS for the characterization of trace elements present in the heavy fractions of petroleum. We present nanoparticle distributions as well as the relative concentrations of elements forming part of nanoparticles and those dissolved into the media. Relative sizes of the metal-containing entities and their concentrations are of great importance in the design of new catalysts and the understanding of the geochemical origin of petroleum.


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EXPERIMENTAL SECTION Reagents and samples. All chemicals used were trace metal grade purity and used without further purification. Direct dilution: o-xylene (Fisher Scientific, Fair Lawn, NJ, USA), mineral oil mineral oil (Fisher Scientific, Fair Lawn, NJ, USA)S, Conostan S21+K 10 mg kg-1 organosoluble standard (Quebec, Canada), Conostan S21+K 885 mg kg-1 organosoluble standard (Quebec, Canada), dispersant (Chevron Oronite, Richmond, CA, USA), Scandium and Yttrium (100 mg kg-1) (Quebec, Canada), Scandium (2000 mg kg-1) (Quebec, Canada), V23 organosoluble standard (LGC, (Manchester, NH, USA), NIST 1634c trace elements in fuel oil Certified Reference Material, CRM (Gaithersburg, MD, USA; Certificate of Analysis (C of A), December 31st, 2020). Ag NP reference materials with a diameter of 60 nm were purchased from nanoComposix (San Diego, USA). Wet Ash Digestion. SPEX multi-element standards (Metuchen, NJ USA), SPEX Scandium 10,000 mg kg-1 (Metuchen, NJ USA); Sulfuric Acid, TraceMetal Grade, 93 to 98%, H2SO4, w/w (Fisher Scientific, Fair Lawn, NJ, USA); Nitric Acid, TraceMetal Grade, 67 to 70%, HNO3, w/w (Fisher Scientific, Fair Lawn, NJ, USA); Hydrochloric acid, TraceMetal Grade, 34 to 37 %, HCl w/w (Fisher Scientific, Fair Lawn, NJ, USA); and water 18.2 MΩ.cm resistivity (MilliQ water, Millipore, Billerica, MA, USA). Asphaltenes were obtained from three samples of different origins. Asphaltene A was obtained from a heavy Mexican crude oil (14 oAPI), Asphaltene B comes from an asphaltenic deposit recovered from a submersible pump, and asphaltene C originates from an oxidized asphalt obtained from a commercial plant. Asphaltenes were extracted using n-heptane at a


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sample/solvent ratio of 1/20. The blended crude oil/heptane was kept at 80 oC for one hour and, then it was filtered through a weighed membrane filter to recover the asphaltenes. Table 1 shows the elemental composition of the three asphaltene samples. Carbon, hydrogen, and nitrogen (CHN) analysis were carried out with a Thermo Scientific Flash 2000. Sulfur was determined using a Leco SC632. Calibration standard preparation. Calibration standards for the ICP-MS and ICP-OES were prepared from different concentrations of Conostan organosoluble standards. For the ICPOES, a diluent containing o-xylene a matrix modifier (mineral oil and dispersant and 5 mg kg-1 Scandium (from 2000 mg kg-1 as an internal standard was used to make the standards. A dilution by weight of Conostan S-21+K 885 mg kg-1 standard with the diluent mentioned above was used to create calibration standards 0, 2, 5 and 10 mg kg-1. The diluent was used as the blank for the calibration. For ICP-MS, a similar diluent and procedure were followed. The only difference was Yttrium (100 mg kg-1) spiked at 0.1 mg kg-1 was also used as an internal standard. Because of the lower operating concentration range, a stock solution, Conostan S-21+K 10 mg kg-1, was utilized for the preparation of the ICP-MS calibration standards. Calibration standards ranging from 1 µg kg-1 to 1000 µg kg-1, prepared by weight with the o-xylene diluent containing a matrix modifier and Scandium and Yttrium as an internal standards were used. The Calibration blank was also the o-xylene diluent containing the internal standards. Reference materials and sample preparation. The nanoparticle reference material and samples were diluted to a particle concentration of between 40 and 1000 ng/g with o-xylene (via PGME) and sonicated for 5 min to ensure sample homogeneity. Dissolved elemental organic standards at concentrations of 10.0 µg/g, were prepared with o-xylene and used to measure the


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elemental response factors. Asphaltene samples were prepared in the same way as the reference materials. For wet acid digestion, a weighed portion of a heated and mixed sample (1 to 5 g) is transferred into a quartz ashing vessel. H2SO4 (93-98 % w/w, 1-2 ml) is added, and the sample can react on a hot plate at 100 °C for four h. After the reaction, the quartz ashing vessel is placed into a programmable ashing furnace (Thermo Scientific Type 6000 furnace, 8 segment programmable, Thermo Fisher Scientific, Fremont, CA, USA) and the ashing sequence is started until reaching a max temp of 610 °C, using a temperature program described as follows: 25°C to 163°C/1 °C/min/120 min // 282 °C/1 °C/min /600 min // 610 °C/1 °C/min/720 min //50 °C/10 °C/min/10 min. Once it is completed, HCl (34 to 37 % w/w, 6 ml), HNO3 (67 to 70 % w/w, 2 ml) are added to the quartz ashing vessel, and the acid dissolution is placed on a hot plate 100 °C for 1h. An internal standard (Sc, 5 mg kg-1) is added to the acid solution and brought to volume final volume (25 ml) with MilliQ water, before analysis on an ICP-OES. Instrumentation. An Agilent 8900 ICP-QQQ was used for this study. The instrument was equipped with platinum sampling and skimmer cones, a concentric glass nebulizer, quartz spray chamber and quartz torch with 1 mm injector. Samples were diluted from 1:2100 up to 1:2700 and, introduced directly into the ICP-MS via a peristaltic pump. By using a highly diluted solution of the sample, the risk of the several colloidal particles occupying the sample droplet after nebulization and forming an agglomerate after the drying of the droplet is minimized. The dilution ensures that every NP signal is produced by a single nanoparticle formerly in the sample.25 Analyses were performed by measuring m/z 51 for V for 56 Fe, 60 for Ni, and 95 Mo for in fast Time-Resolved Analysis (fast TRA) mode, using a dwell time of 0.1 ms (100 µs) per point


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with no settling time between measurements. For all isotopes, the signal was measured on-mass in MS/MS mode, where both quadrupoles (Q1 and Q2) were set to respective m/z. The general settings for the tune mode used for this study are detailed in Table 2. The optional Single Nanoparticle Application Module of the ICP-MS MassHunter software was used particle analysis. Method Wizard guided the process of nanoparticle acquisition and data analysis method development. At the present moment, trace sulfur analysis is complicated by ICP-MS because of molecular oxygen interference, contamination from a gas line or instrument parts among other factors. Because of this limitation, in the present work, it is assumed that the tested elements are in species that have the highest likelihood to be associated with asphaltenes and hydrocarbons in general. The selection of the nature of the mineral nanoparticle affects the particle size distribution. Particle density of the mineral forming the nanoparticle as well as the mass fraction of the element are used in the calculations.26 Therefore, the assumption of different species generates size distributions that are going to be different.

To convert the signals measured with spICP-MS to the particle content of the original sample, it is necessary to calculate or measure the nebulization efficiency. The nebulization efficiency is the ratio of the amount of analyte entering the plasma to the amount of analyte delivered to the nebulizer and was determined using the Ag nanoparticle dispersion (nanoComposix) reference material of known 60 nm particle size. The reference material was first dispersed in PGME, and then further dispersed in o-xylene. In this work, we obtained the nebulization efficiency in two ways. First, measuring the sample uptake mass (g/min) coming into the nebulizer and the drain mass (g/min) coming out of the spray chamber. The difference between them corresponds to the mass of the sample aerosol being delivered to the torch, and the


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nebulization efficiency can be calculated from the mass delivered to the torch divided by the sample uptake mass. Alternatively, nebulization efficiency can be calculated from the certified size of Au NP reference material. Both methods gave the same nebulization efficiency value (0.065 or 6.5%) using the operation conditions in Table 2.


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RESULTS AND DISCUSSION Nanoparticle Size Distributions. Figure 1 presents typical signals for mass 95 (Mo) in sample A as a function of time. Each significant signal or pulse in this spectrum represents an NP containing Mo. The presence of these NPs probably indicates that Mo can be present as an inorganic compound in the asphaltenes or form part of an organic aggregate. Using the raw data shown in Figure 1, it is possible to separate the pulses from the background and obtain a particle size distribution. However, the size distribution is also related to the composition of the nanoparticle. In the case of Mo, it is not known which Mo compounds are associated with petroleum. A plausible inorganic compound is MoS2 (Molybdenite), the most widely distributed Mo mineral,29 and that it is easily formed from oil-soluble Mo complexes in heavy fractions.30 Additionally, MoS2 has been found to be the most abundant form of Mo in asphaltite,31 a type of solid bitumen. By assuming the Mo NPs are mainly composed of MoS2, the size distributions for the different samples were calculated and are shown in Figure 2. As it can be seen in this figure, the distributions are remarkably similar with an average diameter in the range 70 to 80 nm. Characteristics of the distributions considering MoS2 as NP for the three samples are shown in Table 3. In this table, reported values are the average of three independent measurements. Fe is also present as NPs in the samples, as shown in Figure 3 for sample B. In this case, to obtain size distributions, we performed the calculations considering that Fe is present as iron oxides (either as Fe2O3 or Fe3O4) and pyrrhotite (FeS). Iron oxide compounds are commonly found associated to asphaltene deposits16 and pyrrhotite has also been linked to crude oil.32 Previous studies of Fe profiles for bitumens and crude oils using size exclusion chromatography had a single broad peak at a relatively large molecular size that might indicate that they are


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present in larger nanoparticles than V and Ni.21,32 However, these studies included a filtration step that could eliminate the filterable mineral species.32 Figure 4 presents a comparison of the size distributions obtained for Fe2O3 NPs. Independent of the mineral used in the calculations, the results indicate significant differences in sizes among the samples. We found that Fe NPs average sizes follow the order: Sample C> Sample B > Sample A. Characteristics of the distributions obtained for each sample and mineral are shown in Table 4. Signals indicating the presence of clusters of ions were not observed for V nor Ni using spICP-MS. The absence of these signals means that V and Ni are not forming nanoaggregates or if they are trapped in asphaltene nanoaggregates, the number of metals in these nanoaggregates is not enough to produce a significant signal above the background. In summary, our results indicate that the number of these metals trapped in asphaltene nanoaggregates in the tested samples is too low to produce a significant signal. Therefore, these elements are preferentially solubilized in the fluid, and definitely, they are not concentrated in nanoaggregates. Previous evidence has shown that most of the V and Ni are present in the form of porphyrins3 and they can be free8-9 or trapped in asphaltene aggregates.10 However, sharp increases of porphyrin Soret absorption peaks have been observed at low concentrations and attributed to the appearance of free, nonbonded, porphyrin molecules in asphaltene solutions.9 Based on this, it is possible to assume that at the low concentrations used in this work, porphyrin molecules are released from the aggregates and, therefore, V and Ni are not detectable as NPs. Soluble and Insoluble Metal Concentrations. As mentioned before, spICP-MS provides the unique possibility of distinguishing between metals forming nanoparticles and those soluble in the organic matrix.


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Table 5 showed the concentrations of metals in nanoparticles and dissolved in the organic matrix for the different asphaltene samples. This table illustrates that the distribution of metals varies significantly among the different asphaltenes. However, it can be said that molybdenum seems to be preferentially dissolved into the media. Calculations show that between 60 and 99 wt. % of Mo is soluble in the organic matrix.

An earlier study, using Instrumental Neutron

Activation Analysis (INAA), indicated that Mo in asphaltenes is predominantly organically bound.33 Molybdenum has also shown high affinity with organic materials in kerogen.34 In contrast, Fe is mostly present as NPs in two of the asphaltene samples (76 and 91 wt. %), while in the third asphaltene, almost half is in NPs. In the case of soluble Fe, it has been suggested that Fe may be bound to organics through carboxylate complexes.21 Additionally, studies using nano filtration showed that the concentration of Fe in permeates was not correlated to the concentration of asphaltenes for the same crude oil, indicating independence of the asphaltene content and therefore not bound to it. In contrast, in the same study, V and N showed a remarkable linear correlation with asphaltene content.23 These results seem to point out to soluble Fe bounded mainly to maltenes. However, asphaltene C contains a significant amount of iron soluble in the asphaltenes. The presence of this significant soluble Fe amount can be related to the oxidation that increases the number of carboxylic functionalities and therefore, the number of bonding sites for iron cations. Comparison with other ICP-MS methods. In this section, molybdenum and iron concentrations obtained using different preparation methods, direct dilution and wet acid digestion, are compared with the total concentrations obtained using the single particle technique. This comparison is shown in Table 6. For iron, as expected based on recent results,35 single particle values are closer to wet acid digestion ones. It has been shown that direct dilution


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shows a bias towards low concentrations for samples that contain iron nanoparticles.35 It seems that this type of sample preparation precludes an efficient dispersion of nanoparticles in organic solvents and led to a low recovery. In contrast to Fe values, Mo concentrations determined using direct dilution compare very well with those obtained using wet acid digestion. This finding points out to the significant role that the particle size might have in the determination of metals using direct dilution as Fe particles are larger than Mo particles. In fact, laser ablationinductively coupled plasma-mass spectrometry (LA-ICP-MS) studies has shown that large particle fractions are not completely vaporized and ionized in the ICP.36 Regarding molybdenum, results show that for sample A, single particle underestimates the amount of molybdenum when compare with direct dilution and wet acid digestion. The source of this difference is not clear, but it can be related to the selection of the background signal which is considered the largest source of error of the technique. For samples B and C, sp ICP-MS produces larger concentrations than direct dilution and wet acid digestion. Further studies are required to determine if the differences observed are related to the sample nature or they are intrinsic to the technique.

CONCLUSIONS For a first time, it is presented the application of spICP-MS in hydrocarbon media for the study of the nature and characteristics of trace elements in petroleum-related materials. Molybdenum and Iron can be found forming part of nanoparticles. Molybdenum NP size distributions are similar for the three asphaltenes tested, while iron NP sizes increase as total concentration increases.


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No nanoparticles were detected containing nickel and vanadium indicating that these elements are forming metal complexes. It was also found that most of the molybdenum is soluble in the media suggesting also the formation of potential metal complexes. In contrast, iron is mainly forming part of nanoparticles except for the asphaltene extracted from the oxidized asphalt.

Acknowledgement F. Lopez-Linares, Laura Poirier, and E. Rogel want to thank Chevron ETC for the support to carry out this work. J. Nelson and M. Yamanaka would like to thank Steve Wilbur from Agilent Technologies for his guidance and training on sp-ICP-MS.


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REFERENCES 1. Ali, M. F.; Abbas, S. Fuel Processing Technology 2006, 87, 573–584. 2. Erdman, J. G.; Harju, P. H. J. of Chem. Eng. Data 1963, 8, 252-258. 3.

Yin, C.; Tan, X.; Mullen, K.; Stryker, J. M.; Gray, M. R. Energy & Fuels 2008, 22, 2465–2469.

4. Qian, K; Edwards, K. E.; Mennito, A. S.; Walters, C. C.; Kushnerick, J. D. Anal. Chem. 2010, 82, 413-419. 5. Zhao, X.; Liu, Y.; Xu, C.; Yan, Y.; Zhang, Y.; Zhang, Q.; Zhao, S.; Chung, K.; Gray, M. R.; Shi, Q. Energy & Fuels 2013, 27, 2874−2882. 6. Reynolds, J. G.; Gallegos, E. J.; Fish, R. H.; Komlenic J. J. Energy & Fuels 1987,1, 3644. 7. Miller, J. T.; Fisher, R. B.; van der Eerden, A. M. J.; Koningsberger, D. C. Energy & Fuels 1999, 13, 719-727. 8. Wong, G. K.; Yen, T. F. Journal of Petroleum Science and Engineering 2000, 28, 55–64. 9. Evdokimov, I. N.; Fesan, A. A.; Losev, A. P. Energy & Fuels 2017, 31, 1370−1375. 10. Gutierrez Sama, S.; Desprez, A.; Krier, G.; Lienemann, C-P.; Barbier, J.; Lobinski, R.; Barrere-Mangote, C.; Giusti, P.; Bouyssiere, B. Energy & Fuels 2016, 30, 6907−6912. 11. Wong, G. K.; Yen, T. F. Journal of Petroleum Science and Engineering 2000, 28, 55–64. 12. Acevedo, S.; Guzman, K.; Labrador, H.; Carrier, H.; Bouyssiere, B.; Lobinski, R. Energy & Fuels 2012, 26, 4968−4977. 13. Castillo, J.; Vargas, V. Petroleum Science and Technology 2016, 34, 873-879. 14. Lewan, M. D.; Maynard, J. B. Geochimica et Cosmochimica Acta 1982, 46, 2547-2560.


Page 17 of 32

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15. Pillay, A. E.; Bassioni, G.; Stephen, S.; Kühn, F. E. J. Am. Soc. Mass Spectrom. 2011, 22,1403-1408. 16. Carbognani, L. Petroleum Science and Technology 2000, 18, 335-360. 17. Rosales, S.; Machin, I.; Sanchez, M.; Rivas, G. Journal of Molecular Catalysis A: Chemical 2006, 246, 146-153. 18. Castillo, J.; Vargas, V.; Piscitelli, V.; Ordoñez, L.; Rojas, H. Journal of Petroleum Science and Engineering 2017, 151, 248–253. 19. Sakanishi, K.; Saito, I.; Watanabe, I.; Mochida, I. Fuel 2004, 83, 1889-1893. 20. Dehkissia, S.; Larachi, F.; Chornet, E. Fuel, 2004, 83, 1323-1331. 21. Reynolds J. G.; Biggs W. R. Fuel Science & Technology International 1992, 10, 313321. 22. Kaminski, T. J.; Fogler, H. S.; Wolf, N.; Wattana, P.; Mairal, A. Energy & Fuels, 2000, 14, 25–30. 23. Zhao, B.; Shaw, J. M. Energy & Fuels 2007, 21, 2795-2804. 24. Peters, R.; Herrera-Rivera, Z.;

Undas, A.;

van der Lee, M.;

Marvin, H.;

Bouwmeestera, H.; Weigela, S. J. Anal. At. Spectrom. 2015, 30, 1274-1285. 25. Degueldre, C.; Favarger, P. Y. Colloids Surf. A 2003, 217, 137-142. 26. Pace, H. E.; Rogers, N. J.; Jarolimek, C.; Coleman, V. A.; Higgins, C. P. Ranville, J. F. Anal. Chem. 2011, 83, 9361-9369. 27. Olesik, J. W.; Gray, P. J. J. Anal. At. Spectrom., 2012, 27, 1143-1155. 28. Laborda, F.; Jimenez-Lamana, J.; Bolea, E.; Castillo, J. R. J. Anal. At. Spectrom. 2011, 26, 1362-1371.


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29. Hess, F. L. “Molybdenum Deposits. A Short Review”, United States Geological Survey, Bulletin 761, p. 2, Government Printing Office, Washington 1924. 30. Watanabe, I.; Korai, Y.; Mochida, I.; Otake, M.; Yoshimoto, M.; Sakanishi, K., Fuel, 2002, 81, 1515-1520. 31. Aydin, I.; Aydin, F.; Hamamci, C. Fuel 2012, 95, 481–485. 32. Biggs, W. R.; Brown, R. J.; Fetzer, J. Energy & Fuels 1987, 1, 257-262. 33. Jacobs, F. S.; Filby R. H. Anal. Chem. 1983, 55, 74-77. 34. Mercer, G. E.; Fitzgerald, S.; Day, J.; Filby, R. H. Fuel 1993, 72, 1187-1195. 35. Poirier, L.; Nelson, J.; Gilleland, G.; Wall, S.; Berhane, L.; Lopez-Linares, F. Energy & Fuels 2017, 31, 7809−7815. 36. Guillonga M.; Günther, D. J. Anal. At. Spectrom., 2002,17, 831-837.


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TABLE LIST Table 1. Elemental analysis of asphaltene samples. Table 2. Operational variables of the study Table 3. Particle size distributions for Molybdenum as MoS2 NPs. Table 4. Particle size distributions for Iron as Fe3O4, Fe2O3 and FeS Table 5. Concentrations of molybdenum and iron present in nanoparticles and dissolved in the media. Table 6. Total concentrations of molybdenum and iron calculated using sp-ICP-MS and two different preparation techniques (Direct dilution and Wet acid digestion) followed by ICP-MS.


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FIGURE LIST Figure 1. Typical signals for molybdenum (95) as a function of time for asphaltene A. Figure 2. Comparison of size distributions for molybdenum NPs as MoS2. Figure 3. Typical signals for iron(56) as a function of time for asphaltene B. Figure 4. Comparison of size distributions for iron NPs as Fe2O3.


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TABLES


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Table 1. Elemental analysis of asphaltene samples. Carbon

Hydrogen

Nitrogen

Sulfur

Molar H/C

(wt. %)

(wt. %)

(wt. %)

(wt. %)

ratio

A

80.08

7.60

1.02

8.78

1.14

B

88.34

6.72

0.58

3.08

0.91

C

82.81

7.32

0.94

6.14

1.06

Asphaltene


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Table 2. Operational variables of the study Parameter

Value

RF power (W)

1600

Sampling depth (mm)

10

Carrier gas (L/min)

0.35

Spray chamber

5

temperature (oC) Option gas (L/min)

0.35

(Ar 80%, O2 20%) Dwell time (ms)

0.1


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Table 3. Particle size distributions for Molybdenum as MoS2 NPs. Asphaltenes Median (nm) Mean (nm) Mode (nm) A 79 83 69 B 64 69 62 C 69 77 68


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Table 4. Particle size distributions for Iron as Fe3O4, Fe2O3 and FeS Asphaltene

Median (nm)

A B C

196 278 478

Mean (nm)

Mode (nm)

203 312 514

170 222 390

178 273 450

150 194 341

151 232 382

126 164 311

Fe3O4

Fe2O3 A B C

172 244 418 FeS

A B C

146 207 355


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Table 5. Concentrations of molybdenum and iron present in nanoparticles and dissolved in the media. Asphaltenes Molybdenum Iron Nanoparticles Soluble Nanoparticles Soluble -1 -1 -1 (mg kg ) (mg kg ) (mg kg ) (mg kg-1) A 3.48 5.33 54.00 17.00 B 0.04 3.23 173.00 17.00 C 0.07 6.33 457.00 508.00


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Table 6. Total concentrations of molybdenum and iron calculated using sp-ICP-MS and two different preparation techniques (Direct dilution and Wet acid digestion) followed by ICP-MS. Asphaltenes Molybdenum Iron Single Direct Wet Acid Single Direct Wet Acid Particle Dilution Digestion Particle Dilution Digestion (mg kg-1) (mg kg-1) (mg kg-1) (mg kg-1) (mg kg-1) (mg kg-1) A 8.81 39.70 40.44 71.00 39.50 68.04 B 3.27 0.78 0.52 190.00 84.40 221.16 C 6.40 5.89 6.22 965.00 420.00 750.00


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FIGURES


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Figure 1. Typical signals for molybdenum (95) as a function of time for asphaltene A.


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A

B

C

Figure 2. Comparison of size distributions for molybdenum NPs as MoS2.


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Figure 3. Typical signals for iron(56) as a function of time for asphaltene B.


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A

B

C Figure 4. Comparison of size distributions for iron NPs as Fe2O3.


Characterization of Dissolved Metals and Metallic ... - ACS Publications

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