Mercury Sequestration in Alkaline Salt Low-Level Radioactive Waste

Mercury Sequestration in Alkaline Salt Low-Level Radioactive Waste | Research Square window.SnipcartSettings = { analytics: { enabled: false } }; (function() { var accessVector = localStorage.getItem('access_vector') || ''; window.dataLayer = window.dataLayer || []; if (accessVector) { window.dataLayer.push({ user: { profile: { profileInfo: { snid: accessVector } } } }); } })(); (function(w,d,s,l,i){w[l]=w[l]||[];w[l].push({'gtm.start':new Date().getTime(),event:'gtm.js'});var f=d.getElementsByTagName(s)[0],j=d.createElement(s),dl=l!='dataLayer'?'&l='+l:'';j.async=true;j.src='https://www.googletagmanager.com/gtm.js?id='+i+dl;f.parentNode.insertBefore(j,f);})(window,document,'script','dataLayer','GTM-K279D39R'); Browse Preprints In Review Journals COVID-19 Preprints AJE Video Bytes Research Tools Research Promotion AJE Professional Editing AJE Rubriq About Preprint Platform In Review Editorial Policies Our Team Advisory Board Help Center Sign In Submit a Preprint Cite Share Download PDF Research Article Mercury Sequestration in Alkaline Salt Low-Level Radioactive Waste Eric Ryan McCaslin, Katie Ann Hill This is a preprint; it has not been peer reviewed by a journal. https://doi.org/ 10.21203/rs.3.rs-4378423/v1 This work is licensed under a CC BY 4.0 License Status: Published Journal Publication published 03 Jan, 2025 Read the published version in Environmental Science and Pollution Research → Version 1 posted 6 You are reading this latest preprint version Abstract Liquid low-level radioactive waste at the Savannah River Site contains several species of mercury, including inorganic, elemental and methylmercury. This waste is solidified and stabilized in a cementitious waste form referred to as saltstone. Soluble mercury is stabilized as β-cinnabar, HgS as the result of reaction between the mercury and sulfur present in blast furnace slag, one of the cementitious regents. In this investigation, Mersorb ® , a commercial granular activated carbon impregnated with sulfur, was evaluated as a pretreatment to remove mercury from the solution prior to cementation. Mersorb ® was found to remove more than 96 mass percent of the methylmercury in simulated tank waste solution when the mass ratio of Mersorb ® to mercury was above 2.5. Slag sequestered relatively more inorganic mercury than organic mercury in simulated tank waste after 24 hours of contact. This is likely due to the mercury-carbon bond being more covalent than the mercury-oxygen bond and therefore more difficult to break and slower to form HgS. Mercury Sequestration Low-Level Radioactive Waste Slag Granular Activated Carbon Cementitious Material Figures Figure 1 Figure 2 Figure 3 Background Historically, mercury was used to amalgamate and thereby facilitate dissolution of metal cladding and targets irradiated in nuclear reactors at the US Department of Energy Savannah River Site and the Hanford. These sites were responsible for separating radioactive isotope to support the US nuclear defense missions. Dissolution of irradiated reactor assemblies generated caustic liquid waste and precipitated solids which are currently stored as sludge, salt cake, and supernate in carbon steel tanks. The PUREX process introduced mercuric nitrate into the nitric acid dissolvers at the SRS to enhance fuel and target assembly dissolution. Recently, in addition to inorganic Hg(OH) 2 (reported as Hg 2+ ), other Hg species including elemental (Hg 0 ) and organic methylmercury [CH₃Hg]⁺ (MeHg) have been detected in the decontaminated salt solution. (Bannochie, Crawford, et al. 2016 ) Currently over 17 million gallons of salt solution have been solidified at the SRS in the Saltstone Production Facility. Blast furnace slag and thermally beneficiated Class F fly ash are mixed with the waste solution to produce a low activity waste form that meets near surface disposal requirements. The aqueous tank waste containing mercury is a decontaminated sodium salt solution classified as a mixed waste (hazardous and radioactive) (Cs and Sr isotopes were removed along with residual actinides) which carries the Environmental Protection Agency Resource Conservation and Recovery Act (RCRA) characteristic hazardous codes for corrosivity, D002 (pH > 12.5) and toxicity D007 and D009, chromium and mercury, respectively. Characteristic mixed waste can exit RCRA regulations if the hazardous characteristics are treated such that it no longer exhibits corrosivity and toxicity characteristics. Mercury in the tank waste may be in the form of dissolved ions, precipitated solids, or sorbed onto solids. Several forms of mercury have been detected in SRS tank waste. The species have been reported as elemental (metallic Hg 0 ), inorganic ionic in either the + 1 or + 2 oxidation state as Hg 2+ Hg 2 2+ and Hg + 1 , and organic cationic mercury as [CH₃Hg]⁺. (Langton, Bannochie, et al. 2019 ) The organic mercury in the SRS tank waste appears to be the result of chemical reactions between ionic and/or metallic Hg and organic antifoam agents that were used in the evaporator to reduce the waste volume. (Lambert, Howe, et al. 2019 ) Currently, the sequestration chemistry for this waste stream depends on precipitation of HgS. Sulfide is a present in ground granulated blast furnace slag (GGBFS) and becomes available for chemical reactions as the slag hydrates. (Oji and Langton 2019 , Crawford and Hill 2021 ) To date, the Toxicity Characteristic Leaching Procedure (TCLP) results for all samples tested indicated that the total mercury concentrations in TCLP leachates were below the Hg limit of 0.2 mg/L and therefore the cured saltstone was not hazardous for Hg. However, if conditions change, further studies are warranted to assure compliance. Consequently, saltstone exits RCRA requirements and can be disposed of as low-level radioactive waste in the SDF rather than as mixed waste. Experiments reported here were designed to evaluate sequestration of organic mercury which is present in the actual radioactive waste primarily as methyl mercury. Inorganic mercury sequestration chemistry Aqueous wastes containing soluble Hg species are solidified in cementitious waste forms to reduce their mobility and leachability. Mercury sulfide solubility in water at 25°C is less than 1x10 -21 mg/L, which is essentially insoluble and noteworthy relative to other common metals. (Conner 1990 ) In nature, mercury has 3 possible valence states: elemental mercury (Hg 0 ), which has no electric charge, and two positively charged cations, Hg 2+ (mercuric) and Hg 1+ (mercurous). The mercuric cation is generally associated with inorganic molecules, such as sulfur (mineral cinnabar), chlorine (mercuric chloride), oxygen and hydroxyl ions. (Arbestain, Rodriguez-Lado et al. 2009 ) Hg 2+ also forms organic (carbon based) compounds such as mono and dimethylmercury. Elemental mercury is easily absorbed onto particles (Krishnan, Gullett et al. 1994 ) One mechanism for mercury sequestration is metal-ligand interaction, more specifically Lewis acid-base reactions. Hg, Hg 2+ , and Hg 2 2+ have relatively low charge to radius ratios, are relatively more polarizable than most transition metals, have low positive charge, and have completely filled atomic orbitals. They are referred to as “soft” acids when describing stability of metal complexes and the mechanisms of their reactions. Most “soft-metal” ions are soft acids and have filled or nearly filled d subshells. Consequently, metal-to-ligand π bonding is important. Complexes of “soft” metals with “soft” bases are much more stable than would be predicted based on electrostatic properties alone. Sulfide (S 2− ) is a soft base, i.e., “a soft” Lewis base, as the result of its large ionic radii, intermediate electronegativity, and high polarizability. The highly covalent character of many mercuric and mercurous sulfide bonds has been attributed to the existence of an easily distorted 5d10 subshell. Experimental Procedure Work was performed to determine the differences in the chemical reactions between inorganic Hg 2+ and the organometallic cation MeHg + in contact with slag and Mersorb® 1 exposed to tank waste solution. Slag is the grout-forming agent in saltstone responsible for the sequestration of mercury. In addition, the sequestration of mercury using Mersorb® is further investigated, so that it could be an option to incorporate in the Saltstone process to limit the leachability of mercury in the event of higher-than-expected concentrations of methylmercury or for other applications. Simulant Solution Preparation A 2 L batch of simulated waste stock solution (Bannochie 2013 ) was prepared by adding the reagents in the proportion given in Table 1 . The chemicals were added in the order listed in the table. The stock simulant was divided into smaller quantities for preparing solutions with specific mercury compositions. The target MeHg and Hg 2+ concentrations for six test solutions are listed in Table 2 . The simulant stock solutions were spiked with either 1M methylmercury hydroxide solution (Alfa Aesar, lot number M28C026) and/or mercuric nitrate (Acros, lot number A0343549) as shown in Table 3 . The solutions containing mercuric nitrate were heated after addition of this solid Hg regent to facilitate dissolution. Upon cooling, the solution remained precipitate free. One solution, B3, contained both forms of mercury. Table 1 Preparation of simulated stock waste solution Component Mass for 2 L Batch (g) DI Water 100 KNO 3 1.8 Na 2 SO 4 14.9 50% NaOH solution 400.6 DI Water 100 Al(NO 3 ) 3 · 9H 2 O 111 DI Water 100 Na 2 PO 4 · 12H 2 O 3.3 NaCO 3 42 DI Water 100 NaNO 3 290.1 NaNO 2 63.2 DI Water 1233.1 Table 2 Target mercury concentrations Simulant Label Hg added as MeHg (mg/L) a Hg added as Hg(NO 3 ) 2 (mg/L) V 500 0 A 500 0 B1 0 50 B2 100 0 B3 50 50 B4 50 0 a All target Hg 2+ and MeHg concentrations are expressed in terms of mg of Hg per L of solution. The factor for converting mass of [HgCH 3 ] + to Hg is 0.9304. Table 3 Preparation of mercury spiked simulated waste solutions Simulant Label Stock Salt Solution (mL) 1M MeHgOH (mL) Hg(NO 3 ) 2 (mg) V 100 0.215 0 A 250 0.538 0 B1 250 0 33 B2 100 0.050 0 B3 100 a 0.025 0 B4 100 0.025 0 a Solution B3 was prepared by spiking MeHgOH into 100 mL of solution B1. Sequestration Reagents Two reagents known to react with various forms of mercury were selected for preliminary evaluation and comparison of the reaction mechanisms. Mersorb® is a commercial product that consists of granular activated carbon (GAC) that has been impregnated with elemental sulfur. The second reagent, blast furnace slag, meets the specifications for ASTM C989. The suppliers are given in Table 4 . Table 4 Mercury sequestration reagents Component Source Slag Cement Lehigh Cement Company, lot number 634206 Mersorb® NUCON International, Inc. Mercury Sequestration Experiments Mercury-spiked solutions were added to 40 ml vials containing either slag or Mersorb® in amounts shown in Table 5 . Control samples for each of the six spiked simulants were also prepared to determine the concentration of Hg in the contacting solutions without any sequestration reagent. The vials were completely filled with simulant solution to achieve a zero-headspace configuration, then capped, and tumbled in a rotator for 24 ± 2 hours to allow contact between the liquid and solids. The samples were allowed to settle, and the liquid portions were decanted and filtered through 0.2 µm nylon filters. Subsamples were collected in smaller amber glass vials which were also completely filled to achieve a zero-headspace condition. The solutions were analyzed for total mercury content by direct mercury analysis (DMA). (White, Brown, et al. 2019 ) Samples were also analyzed for methylmercury, using purge and trap gas chromatography pyro atomic fluorescence, and ionic mercury (Hg 2+ ) using the stannous chloride reduction method. (Boggess, Bannochie et al. 2019 , Boggess, White 2019) One gram of slag was added to each vial. The mass of Mersorb® added to each vial (25 to 200 mg) was less than the mass of slag added because the density of the Mersorb® was less than that of the slag 0.6 vs 2.9, respectively. Table 5 Ingredients in sequestration samples and control solutions Sample Number Simulant Spiked Salt Solution (g) Spiked Salt Solution (mL) a Sequestration Reagent (mg) Control V V 50.651 41.2 0 Mersorb® V 200 V 51.019 41.5 198 Control A A 52.622 42.8 0 Mersorb® A 25 A 52.570 42.7 24 Mersorb® A 50 A 52.842 43.0 46 Mersorb®A100 A 51.219 41.6 99 Control B1 B1 51.917 42.2 0 Slag B1 B1 51.881 42.2 1005 Control B2 B2 52.449 42.6 0 Slag B2 B2 52.231 42.5 997 Control B3 B3 52.090 42.3 0 Slag B3 B3 51.855 42.2 1011 Control B4 B4 51.955 42.2 0 Slag B4 B4 52.535 42.7 999 a Based on a density of simulated waste stock solution of 1.23 g/mL. [1] Mersorb ® is a trademark of NUCON International, Inc., Columbus, OH, USA Results Sequestration of organic mercury by Mersorb® The measured concentrations of total mercury, added as MeHg, to the spiked simulants prior to contact with Mersorb® and the test solutions are shown in Table 6 . The percentages of mercury removed from the test solutions were calculated based on the measured concentrations in the initial solutions spiked with MeHg as shown in Table 6 . The uncertainty in the total Hg concentrations in the spiked solutions and test solutions measured by DMA was ± 20%. (White, Brown et al. 2019 ) Table 6 Mersorb ® sequestration of Hg added as MeHg Sample Target Hg as MeHg (mg/L) Hg Concentration in Initial Test Solution (mg/L) Hg in Solution after Contact with Mersorb® (mg/L) Percent Hg Removed Control V 500 520 ± 104 - 0 Control A 500 438 ± 88 - 0 Mersorb® V 200 NA 520 ± 104 10.3 ± 2.1 98 Mersorb® A 100 NA 438 ± 88 16.4 ± 3.3 97 Mersorb® A 50 NA 438 ± 88 13.8 ± 2.8 97 Mersorb® A 25 NA 438 ± 88 57.8 ± 11.6 87 The elemental compositions of the spiked test solution before and after contact with Mersorb® were measured by inductively coupled plasma – atomic emission spectroscopy (ICP-AES). Ion chromatography (IC) was used to measure the concentrations of nitrate and nitrate in these solutions. The results are presented in Table 7 . Table 7 Change in dissolved species in solution before and after Mersorb ® contact Dissolved Species Initial Test Solution (mg/L) Solution after Contact with Mersorb® (mg/L) Al 4430 4385 K 370 367 Na 116000 116500 P 362 360 S 1735 1870 NO 3 − 151000 98600 NO 2 − 24850 24350 Sequestration of inorganic and organic mercury by slag In this series of sequestration experiments sequestration of both inorganic ionic mercury added as Hg(NO 3 ) 2 and organic mercury added as a 1M solution of MeHgOH were evaluated. One gram of slag was used as the sequestration reagent. After contact for 24 hours, the solutions were sampled and analyzed for total mercury and mercury species using three different methods to identify speciation: total mercury by DMA, methylmercury by gas chromatography, and inorganic ionic mercury by stannous chloride reduction. Mercury speciation was not determined for the initial and final B1 samples because they were spiked with only inorganic mercury, Hg(NO 3 ) 2 . The total Hg sequestered in each sample was calculated according to Eq. 1, showing a sample calculation for B1. Results are provided in Table 8 . The uncertainty of the DMA measurement for these analyses was reported to be 15%, and the uncertainty of the individual species measurement was 10%. (White, Brown et al. 2019 ) Equation 1 : \(\% Removed= \frac{{C}_{Initial}-{C}_{Final}}{{C}_{Initial}}=\frac{76.3 - 21.1}{76.3}=72.3\%\) Table 8 Slag Sequestration of Organic and Inorganic Mercury Sample ID Target Hg as MeHg (mg/L) Target Hg as Hg 2+ (mg/L) Total Measured Hg by DMA (mg/L) Percent Total Hg Removed Measured Hg 2+ (mg/L) b Measured organic Hg as MeHg (mg/L) c B1 Initial 0 50 76.3 ± 11.4 72.3 NA a NA Final - - 21.1 ± 3.2 NA NA B2 Initial 100 0 101 ± 15 14.9 < 1.0 81.7 ± 8.2 Final - - 86 ± 13 5.55 ± 0.55 49.5 ± 5.0 B3 Initial 50 50 116 ± 17 86.6 42.7 ± 0.43 40.0 ± 4.0 Final - - 15.6 ± 2.3 < 1.0 13.7 ± 1.4 B4 Initial 50 0 48.7 ± 7.3 12.1 < 1.0 41.5 ± 4.2 Final - - 42.8 ± 6.4 4.79 ± 0.48 18.2 ± 1.8 a NA = not analyzed b Stannous chloride reduction method c Purge and trap gas chromatography pyro atomic fluorescence Inorganic ionic mercury was detected in moderate concentrations in two test solutions that were contacted with slag, B2 and B4, even though the initial solutions were only spiked with MeHg. The initial solutions had no detectable inorganic ionic Hg. Therefore, the presence of inorganic Hg was inferred to be generated as the result of reaction of the MeHg with the slag. For three of the solutions (B2 Final, B3 Initial, and B4 Final), the total Hg concentrations calculated from the sums of the individual Hg species measured, MeHg and inorganic mercury, were less than the total measured Hg analyses by DMA. It is possible that in these samples, additional Hg species were present but not measured by the analytical methods used for this study. Discussion Mersorb® Sequestration of Organic Mercury The capacity of Mersorb ® to remove Hg (added as MeHg) from solution in 24 hours was determined by multiplying the initial concentration of Hg in each solution by the volume of solution and then dividing by the mass of Mersorb ® in contact with that solution. Results are plotted in Fig. 1 . The data suggest that greater than 96% of the mercury was absorbed from the simulated waste solution containing up to 0.4 g of mercury per gram of Mersorb®. However, the capacity of Mersorb® to sequester MeHg in the 24-hour exposure tests was exceeded when the concentration of mercury exceeded 0.4 g per gram of Mersorb®. These data extend the previously published results which reported a non-optimized Hg sequestration to Mersorb® value of 0.006 g Hg/1g. (Langton and Oji 2021 ). The concentration for dissolved ions in the simulated waste solution other than mercury were affected by the 24-hour contact with Mersorb®, as seen in Table 7 . The nitrate (NO 3 − ) concentration decrease about 35%, from 151 g/L to 98.6 g/L, which may indicate an affinity of the nitrate ion for the activated carbon, i.e., Mersorb®. The total sulfur concentration increased in the solution at the end of the exposure test compared to the starting concentration. This was attributed to the dissolution of some sulfur from the Mersorb®. Aluminum, potassium, sodium, phosphorous, and nitrite concentrations in the test solutions did not change noticeably before and after the partitioning tests. Slag sequestration of Inorganic and Organic Mercury Over a 24-hour period, slag was found to be much more effective in removing inorganic mercury than in removing organic mercury present from simulated waste solution. The percents of the total mercury (measured by DMA) removed from solutions B1 through B4 were calculated from analyses shown in Table 8 and are graphically represented in Fig. 2 . Inorganic mercury sequestration by slag is faster with in a 24-hour experiment than that of organic methylmercury reaction with slag. After 24-hour exposure testing, inorganic mercury was detected in solutions, B2 and B4, which initially contained only MeHg as shown in Fig. 3 . This suggests that in the presence of slag, the MeHg decomposed to Hg 2+ and methane, CH 4 . Methane generation was also observed in a previous study in which simulated salt solution containing MeHg was contacted with either slag or sodium sulfide (Na 2 S) in a sealed vessel. (Duignan, Crawford et al. 2020 , Duignan, Crawford et al. 2021 ) At the end of these tests, methane was detected in the gas phase inside the vessel which indicates that it was formed during the experiment. Decomposition of the Hg-CH 3 covalent bond to form methane was attributed to the very strong affinity of sulfur/sulfide with all forms of mercury. (Duignan, Crawford et al. 2020 , Duignan, Crawford et al. 2021 ) See Eq. 2. Further support for sulfide being responsible for cleaving the Hg-CH 3 bond was reported in a separate study in which β-HgS (β-cinnabar) was detected in experiments involving slag and MeHg. (Oji and Langton 2019 ) Equation 2. \({CH}_{3}HgOH+ {S}^{2-}+ {H}_{2}O\to \beta HgS+ {{CH}_{4}+2 OH}^{-}\) The Hg-methyl bond (Hg-CH 3 ) is more covalent and therefore more difficult to cleave than the Hg-hydroxyl (Hg-OH) bond. See Eq. 3. The direct sequestration of inorganic mercury by sulfide can be represented by the following reaction. Equation 3. \({Hg\left(OH\right)}_{2}+ {S}^{2-}\to \beta HgS+ {2 OH}^{-}\) Conclusions Radioactive waste solution containing soluble mercury is currently solidified and stabilized in a cementitious waste form. The solution contains inorganic Hg 2+ , organic mercury species primarily MeHg, and Hg 0 . This waste solution is solidified/stabilized in a cementitious waste form containing ground granulated blast furnace slag as the primary reagent. To date, slag has been instrumental in stabilizing all mercury species in the waste. As the slag hydrates sulfide is released from the slag and becomes available to react with soluble mercury. The reaction results in precipitation of nanocrystals of insoluble β-cinnabar, HgS. (Oji and Langton 2019 ) The resulting waste form is classified as nonhazardous for Hg. Recent analyses of the waste solution indicate the increasing concentrations of organic mercury. Experiments were conducted to investigate the efficiency of organic methylmercury sequestration by Mersorb®, a commercial Hg sequestration product, which is porous granular activated carbon impregnated with sulfur. Mersorb® removed at least 96% of the methylmercury in simulated tank waste when the mass ratio of Mersorb® to mercury was above 2.5. These results indicate relatively small additions of Mersorb® can be very effective in sequestering MeHg from salt solution. Experiments were also conducted to identify the reaction mechanism involved in organic and inorganic mercury sequestration by slag. Methylmercury in the simulated waste solution was determined to decompose to methane (CH 4 ) and Hg 2+ in test solutions containing slag. The mercury then precipitated as β-cinnabar, HgS, which is consistent with the previous work in which methane was detected when organic mercury in tank waste was sequestered in a sealed vessel. (Duignan, Crawford et al. 2020 ) In 24-hour exposure tests, slag sequestered inorganic mercury faster than MeHg because the chemical bond between carbon-mercury needed to be broken before the mercuric ion could react with the sulfide ion to precipitate HgS. Declarations This work was funded by the US Department of Energy Environmental Management, Technology Development Office, Project 221818. The authors acknowledge A J Boggess for providing mercury analyses support. Competing Interests The authors have no relevant financial or non-finacial interests to disclose. Ethics Approval Not applicable. Consent to Participate and Consent to Publish Funding This work was supported by the Department of Energy Office of Environmental Management, Technology Development Office (Project # HQ221818). Author Contributions Eric McCaslin and Katie Hill contributed to the study conception, design, and experimental work. Data analysis was performed by Eric McCaslin, and the first draft of the manuscript was written by Eric McCaslin. Both authors worked on revisions of the manuscript, and read and approved the final manuscript. References Arbestain MC, Rodriguez-Lado L, Bao M, Macias F (2009) Assessment of Mercury-Polluted Soils Adjacent to an Old Mercury. -Fulminate Production Plant. Applied and Environmental Soil Science ASTM Standard C989 (2022) Standard Specification for Slag Cement for Use in Concrete and Mortars. ASTM International, West Conshohocken, PA ASTM Standard C1733 (2021) Standard Test Method for Distribution Coefficients of Inorganic Species by Batch Method. 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Savannah River Remediation (Report No. X-SD-Z-00001, Rev 17) White TL, Brown LW, Looney BB, Jones MA (2019) Total Mercury Analysis Comparison. (Report No. SRNL-STI-2019-00056) Cite Share Download PDF Status: Published Journal Publication published 03 Jan, 2025 Read the published version in Environmental Science and Pollution Research → Version 1 posted Editorial decision: Minor Revision 31 Aug, 2024 Reviewers agreed at journal 11 Jun, 2024 Reviewers invited by journal 11 Jun, 2024 Editor invited by journal 27 May, 2024 Editor assigned by journal 20 May, 2024 First submitted to journal 16 May, 2024 You are reading this latest preprint version Research Square lets you share your work early, gain feedback from the community, and start making changes to your manuscript prior to peer review in a journal. As a division of Research Square Company, we’re committed to making research communication faster, fairer, and more useful. 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Also discoverable on Platform About Our Team In Review Editorial Policies Advisory Board Help Center Resources Author Services Accessibility API Access RSS feed Manage Cookie Preferences © Research Square 2026 | ISSN 2693-5015 (online) Privacy Policy Terms of Service Do Not Sell My Personal Information {"props":{"pageProps":{"initialData":{"identity":"rs-4378423","acceptedTermsAndConditions":true,"allowDirectSubmit":false,"archivedVersions":[],"articleType":"Research Article","associatedPublications":[],"authors":[{"id":313036696,"identity":"2efd5472-8c30-43f6-aca1-9d256c7bce87","order_by":0,"name":"Eric Ryan McCaslin","email":"data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAAZAAAAAyAQMAAABI0h/eAAAABlBMVEX///8AAABVwtN+AAAACXBIWXMAAA7EAAAOxAGVKw4bAAABB0lEQVRIie3RMWrDMBSA4fcQNIuNV4VAfQV1KoZiX8XGa6F0yxCCgiBZQrI6EHKHLoJuMoJkEWT12hu4dC9VWhdCUZt0K0X/Ii0fepIAfL4/GfJuQ7iCoV17APRMgpaYAz1Jji1OzyDRQE9avE3jaFlP9P1mfHdNAJt2COmS5k7SXxSCoiyvqqbgeiV18iiAJJWBclW5CTN2GJQqhwa5DqViTMPFIJxCyYxykuyTxPvakvW4I6/fExZ0hCk7WMhJRzikbMedhBoUtLB3eTjcJdhqS1Ak1Zbm/ZmbRPPeU/ss0/hyr/VLMLKD7UTdtKObLCJO8dGXl3n/XFq4z/ip7NfC5/P5/mtvfBRb6secwP8AAAAASUVORK5CYII=","orcid":"https://orcid.org/0000-0001-5878-3093","institution":"Savannah River National Laboratory","correspondingAuthor":true,"prefix":"","firstName":"Eric","middleName":"Ryan","lastName":"McCaslin","suffix":""},{"id":313036697,"identity":"900e9de0-00d7-40a2-868f-002c833f638b","order_by":1,"name":"Katie Ann Hill","email":"","orcid":"","institution":"Savannah River National Laboratory","correspondingAuthor":false,"prefix":"","firstName":"Katie","middleName":"Ann","lastName":"Hill","suffix":""}],"badges":[],"createdAt":"2024-05-06 17:20:04","currentVersionCode":1,"declarations":"","doi":"10.21203/rs.3.rs-4378423/v1","doiUrl":"https://doi.org/10.21203/rs.3.rs-4378423/v1","draftVersion":[],"editorialEvents":[{"content":"https://doi.org/10.1007/s11356-024-35630-7","type":"published","date":"2025-01-03T15:57:14+00:00"}],"editorialNote":"","failedWorkflow":false,"files":[{"id":59181872,"identity":"8014f1cc-865d-4774-b2a7-6ca893e7ac85","added_by":"auto","created_at":"2024-06-27 10:51:29","extension":"png","order_by":1,"title":"Figure 1","display":"","copyAsset":false,"role":"figure","size":21364,"visible":true,"origin":"","legend":"\u003cp\u003ePercent Hg removed from MeHg spiked simulated waste solutions as a function of the amount of Mersorb\u003csup\u003e®\u003c/sup\u003e in the solutions.\u003c/p\u003e","description":"","filename":"1.png","url":"https://assets-eu.researchsquare.com/files/rs-4378423/v1/2ac0f354ea965007c1842866.png"},{"id":59181874,"identity":"dc8f7eb3-dae8-493b-8e69-6b7fc5a6a0e5","added_by":"auto","created_at":"2024-06-27 10:51:29","extension":"png","order_by":2,"title":"Figure 2","display":"","copyAsset":false,"role":"figure","size":20860,"visible":true,"origin":"","legend":"\u003cp\u003ePercent total mercury sequestered from simulated waste solution by slag after 24-hour exposures for simulants spiked with MeHg or Hg\u003csup\u003e2+\u003c/sup\u003e or a combination of both.\u003c/p\u003e","description":"","filename":"2.png","url":"https://assets-eu.researchsquare.com/files/rs-4378423/v1/a4b7f8fec3d0b1805c47546f.png"},{"id":59181873,"identity":"c06fadeb-a7ba-4842-9002-cf5823c7c22f","added_by":"auto","created_at":"2024-06-27 10:51:29","extension":"png","order_by":3,"title":"Figure 3","display":"","copyAsset":false,"role":"figure","size":39987,"visible":true,"origin":"","legend":"\u003cp\u003eSpeciation of mercury in solution after contact with slag, depending on the initial composition of the mercury, normalized to 100% for each.\u003c/p\u003e","description":"","filename":"3.png","url":"https://assets-eu.researchsquare.com/files/rs-4378423/v1/17e2d81acc3e17269ca6521b.png"},{"id":73093212,"identity":"6f1677c7-d2b2-4f7b-a5ba-4a248fdce68c","added_by":"auto","created_at":"2025-01-06 16:10:49","extension":"pdf","order_by":0,"title":"","display":"","copyAsset":false,"role":"manuscript-pdf","size":870976,"visible":true,"origin":"","legend":"","description":"","filename":"manuscript.pdf","url":"https://assets-eu.researchsquare.com/files/rs-4378423/v1/eace784f-ddd3-4371-a701-8ce50ad72359.pdf"}],"financialInterests":"","formattedTitle":"Mercury Sequestration in Alkaline Salt Low-Level Radioactive Waste","fulltext":[{"header":"Background","content":"\u003cp\u003eHistorically, mercury was used to amalgamate and thereby facilitate dissolution of metal cladding and targets irradiated in nuclear reactors at the US Department of Energy Savannah River Site and the Hanford. These sites were responsible for separating radioactive isotope to support the US nuclear defense missions. Dissolution of irradiated reactor assemblies generated caustic liquid waste and precipitated solids which are currently stored as sludge, salt cake, and supernate in carbon steel tanks.\u003c/p\u003e \u003cp\u003eThe PUREX process introduced mercuric nitrate into the nitric acid dissolvers at the SRS to enhance fuel and target assembly dissolution. Recently, in addition to inorganic Hg(OH)\u003csub\u003e2\u003c/sub\u003e (reported as Hg\u003csup\u003e2+\u003c/sup\u003e), other Hg species including elemental (Hg\u003csup\u003e0\u003c/sup\u003e) and organic methylmercury [CH₃Hg]⁺ (MeHg) have been detected in the decontaminated salt solution. (Bannochie, Crawford, et al. \u003cspan citationid=\"CR5\" class=\"CitationRef\"\u003e2016\u003c/span\u003e) Currently over 17\u0026nbsp;million gallons of salt solution have been solidified at the SRS in the Saltstone Production Facility. Blast furnace slag and thermally beneficiated Class F fly ash are mixed with the waste solution to produce a low activity waste form that meets near surface disposal requirements.\u003c/p\u003e \u003cp\u003eThe aqueous tank waste containing mercury is a decontaminated sodium salt solution classified as a mixed waste (hazardous and radioactive) (Cs and Sr isotopes were removed along with residual actinides) which carries the Environmental Protection Agency Resource Conservation and Recovery Act (RCRA) characteristic hazardous codes for corrosivity, D002 (pH \u0026gt; 12.5) and toxicity D007 and D009, chromium and mercury, respectively. Characteristic mixed waste can exit RCRA regulations if the hazardous characteristics are treated such that it no longer exhibits corrosivity and toxicity characteristics. Mercury in the tank waste may be in the form of dissolved ions, precipitated solids, or sorbed onto solids. Several forms of mercury have been detected in SRS tank waste. The species have been reported as elemental (metallic Hg\u003csup\u003e0\u003c/sup\u003e), inorganic ionic in either the + 1 or + 2 oxidation state as Hg\u003csup\u003e2+\u003c/sup\u003e Hg\u003csub\u003e2\u003c/sub\u003e\u003csup\u003e2+\u003c/sup\u003e and Hg\u003csup\u003e+ 1\u003c/sup\u003e, and organic cationic mercury as [CH₃Hg]⁺. (Langton, Bannochie, et al. \u003cspan citationid=\"CR14\" class=\"CitationRef\"\u003e2019\u003c/span\u003e) The organic mercury in the SRS tank waste appears to be the result of chemical reactions between ionic and/or metallic Hg and organic antifoam agents that were used in the evaporator to reduce the waste volume. (Lambert, Howe, et al. \u003cspan citationid=\"CR13\" class=\"CitationRef\"\u003e2019\u003c/span\u003e)\u003c/p\u003e \u003cp\u003eCurrently, the sequestration chemistry for this waste stream depends on precipitation of HgS. Sulfide is a present in ground granulated blast furnace slag (GGBFS) and becomes available for chemical reactions as the slag hydrates. (Oji and Langton \u003cspan citationid=\"CR17\" class=\"CitationRef\"\u003e2019\u003c/span\u003e, Crawford and Hill \u003cspan citationid=\"CR9\" class=\"CitationRef\"\u003e2021\u003c/span\u003e) To date, the Toxicity Characteristic Leaching Procedure (TCLP) results for all samples tested indicated that the total mercury concentrations in TCLP leachates were below the Hg limit of 0.2 mg/L and therefore the cured saltstone was not hazardous for Hg. However, if conditions change, further studies are warranted to assure compliance. Consequently, saltstone exits RCRA requirements and can be disposed of as low-level radioactive waste in the SDF rather than as mixed waste. Experiments reported here were designed to evaluate sequestration of organic mercury which is present in the actual radioactive waste primarily as methyl mercury.\u003c/p\u003e\n\u003ch3\u003eInorganic mercury sequestration chemistry\u003c/h3\u003e\n\u003cp\u003eAqueous wastes containing soluble Hg species are solidified in cementitious waste forms to reduce their mobility and leachability. Mercury sulfide solubility in water at 25°C is less than 1x10\u003csup\u003e-21\u003c/sup\u003e mg/L, which is essentially insoluble and noteworthy relative to other common metals. (Conner \u003cspan citationid=\"CR8\" class=\"CitationRef\"\u003e1990\u003c/span\u003e) In nature, mercury has 3 possible valence states: elemental mercury (Hg\u003csup\u003e0\u003c/sup\u003e), which has no electric charge, and two positively charged cations, Hg\u003csup\u003e2+\u003c/sup\u003e (mercuric) and Hg\u003csup\u003e1+\u003c/sup\u003e (mercurous). The mercuric cation is generally associated with inorganic molecules, such as sulfur (mineral cinnabar), chlorine (mercuric chloride), oxygen and hydroxyl ions. (Arbestain, Rodriguez-Lado et al. \u003cspan citationid=\"CR1\" class=\"CitationRef\"\u003e2009\u003c/span\u003e) Hg\u003csup\u003e2+\u003c/sup\u003e also forms organic (carbon based) compounds such as mono and dimethylmercury. Elemental mercury is easily absorbed onto particles (Krishnan, Gullett et al. \u003cspan citationid=\"CR12\" class=\"CitationRef\"\u003e1994\u003c/span\u003e)\u003c/p\u003e \u003cp\u003eOne mechanism for mercury sequestration is metal-ligand interaction, more specifically Lewis acid-base reactions. Hg, Hg\u003csup\u003e2+\u003c/sup\u003e, and Hg\u003csub\u003e2\u003c/sub\u003e\u003csup\u003e2+\u003c/sup\u003e have relatively low charge to radius ratios, are relatively more polarizable than most transition metals, have low positive charge, and have completely filled atomic orbitals. They are referred to as “soft” acids when describing stability of metal complexes and the mechanisms of their reactions.\u003c/p\u003e \u003cp\u003eMost “soft-metal” ions are soft acids and have filled or nearly filled d subshells. Consequently, metal-to-ligand π bonding is important. Complexes of “soft” metals with “soft” bases are much more stable than would be predicted based on electrostatic properties alone. Sulfide (S\u003csup\u003e2−\u003c/sup\u003e) is a soft base, i.e., “a soft” Lewis base, as the result of its large ionic radii, intermediate electronegativity, and high polarizability. The highly covalent character of many mercuric and mercurous sulfide bonds has been attributed to the existence of an easily distorted 5d10 subshell.\u003c/p\u003e "},{"header":"Experimental Procedure","content":"\u003cp\u003eWork was performed to determine the differences in the chemical reactions between inorganic Hg\u003csup\u003e2+\u003c/sup\u003e and the organometallic cation MeHg + in contact with slag and Mersorb®\u003ca class=\"FNLink\" href=\"#Fn1\" id=\"#FNLinkFn1\"\u003e1\u003c/a\u003e exposed to tank waste solution. Slag is the grout-forming agent in saltstone responsible for the sequestration of mercury. In addition, the sequestration of mercury using Mersorb® is further investigated, so that it could be an option to incorporate in the Saltstone process to limit the leachability of mercury in the event of higher-than-expected concentrations of methylmercury or for other applications.\u003c/p\u003e\u003ch2\u003eSimulant Solution Preparation\u003c/h2\u003e\u003cp\u003eA 2 L batch of simulated waste stock solution (Bannochie \u003cspan citationid=\"CR4\" class=\"CitationRef\"\u003e2013\u003c/span\u003e) was prepared by adding the reagents in the proportion given in Table\u0026nbsp;\u003cspan refid=\"Tab1\" class=\"InternalRef\"\u003e1\u003c/span\u003e. The chemicals were added in the order listed in the table. The stock simulant was divided into smaller quantities for preparing solutions with specific mercury compositions. The target MeHg and Hg\u003csup\u003e2+\u003c/sup\u003e concentrations for six test solutions are listed in Table\u0026nbsp;\u003cspan refid=\"Tab2\" class=\"InternalRef\"\u003e2\u003c/span\u003e. The simulant stock solutions were spiked with either 1M methylmercury hydroxide solution (Alfa Aesar, lot number M28C026) and/or mercuric nitrate (Acros, lot number A0343549) as shown in Table\u0026nbsp;\u003cspan refid=\"Tab3\" class=\"InternalRef\"\u003e3\u003c/span\u003e. The solutions containing mercuric nitrate were heated after addition of this solid Hg regent to facilitate dissolution. Upon cooling, the solution remained precipitate free. One solution, B3, contained both forms of mercury.\u003c/p\u003e\u003cp\u003e \u003c/p\u003e\u003cdiv class=\"gridtable\"\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c1\" colnum=\"1\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c2\" colnum=\"2\"\u003e\u003c/div\u003e\u003ctable float=\"Yes\" id=\"Tab1\" border=\"1\"\u003e\u003ccaption language=\"En\"\u003e \u003cdiv class=\"CaptionNumber\"\u003eTable 1\u003c/div\u003e \u003cdiv class=\"CaptionContent\"\u003e \u003cp\u003ePreparation of simulated stock waste solution\u003c/p\u003e \u003c/div\u003e \u003c/caption\u003e\u003ccolgroup cols=\"2\"\u003e\u003c/colgroup\u003e\u003cthead\u003e\u003ctr\u003e\u003cth align=\"left\" colname=\"c1\"\u003e \u003cp\u003eComponent\u003c/p\u003e \u003c/th\u003e\u003cth align=\"left\" colname=\"c2\"\u003e \u003cp\u003eMass for 2 L Batch (g)\u003c/p\u003e \u003c/th\u003e\u003c/tr\u003e\u003c/thead\u003e\u003ctbody\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eDI Water\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e100\u003c/p\u003e \u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eKNO\u003csub\u003e3\u003c/sub\u003e\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e1.8\u003c/p\u003e \u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eNa\u003csub\u003e2\u003c/sub\u003eSO\u003csub\u003e4\u003c/sub\u003e\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e14.9\u003c/p\u003e \u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e50% NaOH solution\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e400.6\u003c/p\u003e \u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eDI Water\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e100\u003c/p\u003e \u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eAl(NO\u003csub\u003e3\u003c/sub\u003e)\u003csub\u003e3\u003c/sub\u003e · 9H\u003csub\u003e2\u003c/sub\u003eO\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e111\u003c/p\u003e \u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eDI Water\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e100\u003c/p\u003e \u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eNa\u003csub\u003e2\u003c/sub\u003ePO\u003csub\u003e4\u003c/sub\u003e · 12H\u003csub\u003e2\u003c/sub\u003eO\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e3.3\u003c/p\u003e \u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eNaCO\u003csub\u003e3\u003c/sub\u003e\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e42\u003c/p\u003e \u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eDI Water\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e100\u003c/p\u003e \u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eNaNO\u003csub\u003e3\u003c/sub\u003e\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e290.1\u003c/p\u003e \u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eNaNO\u003csub\u003e2\u003c/sub\u003e\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e63.2\u003c/p\u003e \u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eDI Water\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e1233.1\u003c/p\u003e \u003c/td\u003e\u003c/tr\u003e\u003c/tbody\u003e\u003c/table\u003e\u003c/div\u003e\u003cp\u003e\u003c/p\u003e\u003cp\u003e \u003c/p\u003e\u003cdiv class=\"gridtable\"\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c1\" colnum=\"1\"\u003e\u003c/div\u003e\u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c2\" colnum=\"2\"\u003e\u003c/div\u003e\u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c3\" colnum=\"3\"\u003e\u003c/div\u003e\u003ctable float=\"Yes\" id=\"Tab2\" border=\"1\"\u003e\u003ccaption language=\"En\"\u003e \u003cdiv class=\"CaptionNumber\"\u003eTable 2\u003c/div\u003e \u003cdiv class=\"CaptionContent\"\u003e \u003cp\u003eTarget mercury concentrations\u003c/p\u003e \u003c/div\u003e \u003c/caption\u003e\u003ccolgroup cols=\"3\"\u003e\u003c/colgroup\u003e\u003cthead\u003e\u003ctr\u003e\u003cth align=\"left\" colname=\"c1\"\u003e \u003cp\u003eSimulant Label\u003c/p\u003e \u003c/th\u003e\u003cth align=\"left\" colname=\"c2\"\u003e \u003cp\u003eHg added as MeHg (mg/L)\u003csup\u003ea\u003c/sup\u003e\u003c/p\u003e \u003c/th\u003e\u003cth align=\"left\" colname=\"c3\"\u003e \u003cp\u003eHg added as Hg(NO\u003csub\u003e3\u003c/sub\u003e)\u003csub\u003e2\u003c/sub\u003e\u003c/p\u003e \u003cp\u003e(mg/L)\u003c/p\u003e \u003c/th\u003e\u003c/tr\u003e\u003c/thead\u003e\u003ctbody\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eV\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e500\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e0\u003c/p\u003e \u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eA\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e500\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e0\u003c/p\u003e \u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eB1\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e0\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e50\u003c/p\u003e \u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eB2\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e100\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e0\u003c/p\u003e \u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eB3\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e50\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e50\u003c/p\u003e \u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eB4\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e50\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e0\u003c/p\u003e \u003c/td\u003e\u003c/tr\u003e\u003c/tbody\u003e\u003c/table\u003e\u003c/div\u003e\u003cp\u003e\u003c/p\u003e\u003cp\u003e \u003csup\u003ea\u003c/sup\u003eAll target Hg\u003csup\u003e2+\u003c/sup\u003e and MeHg concentrations are expressed in terms of mg of Hg per L of solution. The factor for converting mass of [HgCH\u003csub\u003e3\u003c/sub\u003e]\u003csup\u003e+\u003c/sup\u003e to Hg is 0.9304.\u003c/p\u003e\u003cp\u003e \u003c/p\u003e\u003cdiv class=\"gridtable\"\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c1\" colnum=\"1\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c2\" colnum=\"2\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c3\" colnum=\"3\"\u003e\u003c/div\u003e\u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c4\" colnum=\"4\"\u003e\u003c/div\u003e\u003ctable float=\"Yes\" id=\"Tab3\" border=\"1\"\u003e\u003ccaption language=\"En\"\u003e \u003cdiv class=\"CaptionNumber\"\u003eTable 3\u003c/div\u003e \u003cdiv class=\"CaptionContent\"\u003e \u003cp\u003ePreparation of mercury spiked simulated waste solutions\u003c/p\u003e \u003c/div\u003e \u003c/caption\u003e\u003ccolgroup cols=\"4\"\u003e\u003c/colgroup\u003e\u003cthead\u003e\u003ctr\u003e\u003cth align=\"left\" colname=\"c1\"\u003e \u003cp\u003eSimulant Label\u003c/p\u003e \u003c/th\u003e\u003cth align=\"left\" colname=\"c2\"\u003e \u003cp\u003eStock Salt Solution (mL)\u003c/p\u003e \u003c/th\u003e\u003cth align=\"left\" colname=\"c3\"\u003e \u003cp\u003e1M MeHgOH\u003c/p\u003e \u003cp\u003e(mL)\u003c/p\u003e \u003c/th\u003e\u003cth align=\"left\" colname=\"c4\"\u003e \u003cp\u003eHg(NO\u003csub\u003e3\u003c/sub\u003e)\u003csub\u003e2\u003c/sub\u003e\u003c/p\u003e \u003cp\u003e(mg)\u003c/p\u003e \u003c/th\u003e\u003c/tr\u003e\u003c/thead\u003e\u003ctbody\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eV\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e100\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e0.215\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e0\u003c/p\u003e \u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eA\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e250\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e0.538\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e0\u003c/p\u003e \u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eB1\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e250\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e0\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e33\u003c/p\u003e \u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eB2\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e100\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e0.050\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e0\u003c/p\u003e \u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eB3\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e100\u003csup\u003ea\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e0.025\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e0\u003c/p\u003e \u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eB4\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e100\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e0.025\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e0\u003c/p\u003e \u003c/td\u003e\u003c/tr\u003e\u003c/tbody\u003e\u003c/table\u003e\u003c/div\u003e\u003cp\u003e\u003c/p\u003e\u003cp\u003e \u003csup\u003ea\u003c/sup\u003eSolution B3 was prepared by spiking MeHgOH into 100 mL of solution B1.\u003c/p\u003e\u003ch2\u003eSequestration Reagents\u003c/h2\u003e\u003cp\u003eTwo reagents known to react with various forms of mercury were selected for preliminary evaluation and comparison of the reaction mechanisms. Mersorb® is a commercial product that consists of granular activated carbon (GAC) that has been impregnated with elemental sulfur. The second reagent, blast furnace slag, meets the specifications for ASTM C989. The suppliers are given in Table\u0026nbsp;\u003cspan refid=\"Tab4\" class=\"InternalRef\"\u003e4\u003c/span\u003e.\u003c/p\u003e\u003cp\u003e \u003c/p\u003e\u003cdiv class=\"gridtable\"\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c1\" colnum=\"1\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c2\" colnum=\"2\"\u003e\u003c/div\u003e\u003ctable float=\"Yes\" id=\"Tab4\" border=\"1\"\u003e\u003ccaption language=\"En\"\u003e \u003cdiv class=\"CaptionNumber\"\u003eTable 4\u003c/div\u003e \u003cdiv class=\"CaptionContent\"\u003e \u003cp\u003eMercury sequestration reagents\u003c/p\u003e \u003c/div\u003e \u003c/caption\u003e\u003ccolgroup cols=\"2\"\u003e\u003c/colgroup\u003e\u003cthead\u003e\u003ctr\u003e\u003cth align=\"left\" colname=\"c1\"\u003e \u003cp\u003eComponent\u003c/p\u003e \u003c/th\u003e\u003cth align=\"left\" colname=\"c2\"\u003e \u003cp\u003eSource\u003c/p\u003e \u003c/th\u003e\u003c/tr\u003e\u003c/thead\u003e\u003ctbody\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eSlag Cement\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eLehigh Cement Company, lot number 634206\u003c/p\u003e \u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eMersorb®\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eNUCON International, Inc.\u003c/p\u003e \u003c/td\u003e\u003c/tr\u003e\u003c/tbody\u003e\u003c/table\u003e\u003c/div\u003e\u003cp\u003e\u003c/p\u003e\u003ch2\u003eMercury Sequestration Experiments\u003c/h2\u003e\u003cp\u003eMercury-spiked solutions were added to 40 ml vials containing either slag or Mersorb® in amounts shown in Table\u0026nbsp;\u003cspan refid=\"Tab5\" class=\"InternalRef\"\u003e5\u003c/span\u003e. Control samples for each of the six spiked simulants were also prepared to determine the concentration of Hg in the contacting solutions without any sequestration reagent. The vials were completely filled with simulant solution to achieve a zero-headspace configuration, then capped, and tumbled in a rotator for 24 ± 2 hours to allow contact between the liquid and solids. The samples were allowed to settle, and the liquid portions were decanted and filtered through 0.2 µm nylon filters. Subsamples were collected in smaller amber glass vials which were also completely filled to achieve a zero-headspace condition. The solutions were analyzed for total mercury content by direct mercury analysis (DMA). (White, Brown, et al. \u003cspan citationid=\"CR19\" class=\"CitationRef\"\u003e2019\u003c/span\u003e) Samples were also analyzed for methylmercury, using purge and trap gas chromatography pyro atomic fluorescence, and ionic mercury (Hg\u003csup\u003e2+\u003c/sup\u003e) using the stannous chloride reduction method. (Boggess, Bannochie et al. \u003cspan citationid=\"CR6\" class=\"CitationRef\"\u003e2019\u003c/span\u003e, Boggess, White 2019) One gram of slag was added to each vial. The mass of Mersorb® added to each vial (25 to 200 mg) was less than the mass of slag added because the density of the Mersorb® was less than that of the slag 0.6 vs 2.9, respectively.\u003c/p\u003e\u003cp\u003e \u003c/p\u003e\u003cdiv class=\"gridtable\"\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c1\" colnum=\"1\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c2\" colnum=\"2\"\u003e\u003c/div\u003e\u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c3\" colnum=\"3\"\u003e\u003c/div\u003e\u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c4\" colnum=\"4\"\u003e\u003c/div\u003e\u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c5\" colnum=\"5\"\u003e\u003c/div\u003e\u003ctable float=\"Yes\" id=\"Tab5\" border=\"1\"\u003e\u003ccaption language=\"En\"\u003e \u003cdiv class=\"CaptionNumber\"\u003eTable 5\u003c/div\u003e \u003cdiv class=\"CaptionContent\"\u003e \u003cp\u003eIngredients in sequestration samples and control solutions\u003c/p\u003e \u003c/div\u003e \u003c/caption\u003e\u003ccolgroup cols=\"5\"\u003e\u003c/colgroup\u003e\u003cthead\u003e\u003ctr\u003e\u003cth align=\"left\" colname=\"c1\"\u003e \u003cp\u003eSample Number\u003c/p\u003e \u003c/th\u003e\u003cth align=\"left\" colname=\"c2\"\u003e \u003cp\u003eSimulant\u003c/p\u003e \u003c/th\u003e\u003cth align=\"left\" colname=\"c3\"\u003e \u003cp\u003eSpiked Salt Solution (g)\u003c/p\u003e \u003c/th\u003e\u003cth align=\"left\" colname=\"c4\"\u003e \u003cp\u003eSpiked Salt Solution (mL)\u003csup\u003ea\u003c/sup\u003e\u003c/p\u003e \u003c/th\u003e\u003cth align=\"left\" colname=\"c5\"\u003e \u003cp\u003eSequestration Reagent (mg)\u003c/p\u003e \u003c/th\u003e\u003c/tr\u003e\u003c/thead\u003e\u003ctbody\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eControl V\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eV\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e50.651\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e41.2\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e0\u003c/p\u003e \u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eMersorb® V 200\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eV\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e51.019\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e41.5\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e198\u003c/p\u003e \u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eControl A\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eA\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e52.622\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e42.8\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e0\u003c/p\u003e \u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eMersorb® A 25\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eA\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e52.570\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e42.7\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e24\u003c/p\u003e \u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eMersorb® A 50\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eA\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e52.842\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e43.0\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e46\u003c/p\u003e \u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eMersorb®A100\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eA\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e51.219\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e41.6\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e99\u003c/p\u003e \u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eControl B1\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eB1\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e51.917\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e42.2\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e0\u003c/p\u003e \u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eSlag B1\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eB1\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e51.881\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e42.2\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e1005\u003c/p\u003e \u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eControl B2\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eB2\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e52.449\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e42.6\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e0\u003c/p\u003e \u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eSlag B2\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eB2\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e52.231\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e42.5\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e997\u003c/p\u003e \u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eControl B3\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eB3\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e52.090\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e42.3\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e0\u003c/p\u003e \u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eSlag B3\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eB3\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e51.855\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e42.2\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e1011\u003c/p\u003e \u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eControl B4\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eB4\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e51.955\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e42.2\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e0\u003c/p\u003e \u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eSlag B4\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eB4\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e52.535\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e42.7\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e999\u003c/p\u003e \u003c/td\u003e\u003c/tr\u003e\u003c/tbody\u003e\u003c/table\u003e\u003c/div\u003e\u003cp\u003e\u003c/p\u003e\u003cp\u003e \u003csup\u003ea\u003c/sup\u003eBased on a density of simulated waste stock solution of 1.23 g/mL.\u003c/p\u003e\n\u003cp\u003e[1] Mersorb\u003csup\u003e\u0026reg;\u003c/sup\u003e is a trademark of NUCON International, Inc., Columbus, OH, USA\u003c/p\u003e\n\u003cp\u003e\u003cbr\u003e\u003c/p\u003e"},{"header":"Results","content":"\u003cdiv id=\"Sec8\" class=\"Section2\"\u003e \u003ch2\u003eSequestration of organic mercury by Mersorb\u0026reg;\u003c/h2\u003e \u003cp\u003eThe measured concentrations of total mercury, added as MeHg, to the spiked simulants prior to contact with Mersorb\u0026reg; and the test solutions are shown in Table\u0026nbsp;\u003cspan refid=\"Tab6\" class=\"InternalRef\"\u003e6\u003c/span\u003e. The percentages of mercury removed from the test solutions were calculated based on the measured concentrations in the initial solutions spiked with MeHg as shown in Table\u0026nbsp;\u003cspan refid=\"Tab6\" class=\"InternalRef\"\u003e6\u003c/span\u003e. The uncertainty in the total Hg concentrations in the spiked solutions and test solutions measured by DMA was \u0026plusmn;\u0026thinsp;20%. (White, Brown et al. \u003cspan citationid=\"CR19\" class=\"CitationRef\"\u003e2019\u003c/span\u003e)\u003c/p\u003e \u003cp\u003e \u003cdiv class=\"gridtable\"\u003e\u003ctable float=\"Yes\" id=\"Tab6\" border=\"1\"\u003e \u003ccaption language=\"En\"\u003e \u003cdiv class=\"CaptionNumber\"\u003eTable 6\u003c/div\u003e \u003cdiv class=\"CaptionContent\"\u003e \u003cp\u003eMersorb\u003csup\u003e\u0026reg;\u003c/sup\u003e sequestration of Hg added as MeHg\u003c/p\u003e \u003c/div\u003e \u003c/caption\u003e \u003ccolgroup cols=\"5\"\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c1\" colnum=\"1\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c2\" colnum=\"2\"\u003e\u003c/div\u003e \u003cdiv align=\"char\" char=\"\u0026plusmn;\" class=\"colspec\" colname=\"c3\" colnum=\"3\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c4\" colnum=\"4\"\u003e\u003c/div\u003e \u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c5\" colnum=\"5\"\u003e\u003c/div\u003e \u003cthead\u003e \u003ctr\u003e \u003cth align=\"left\" colname=\"c1\"\u003e \u003cp\u003eSample\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c2\"\u003e \u003cp\u003eTarget\u003c/p\u003e \u003cp\u003eHg as MeHg\u003c/p\u003e \u003cp\u003e(mg/L)\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c3\"\u003e \u003cp\u003eHg Concentration in Initial Test Solution\u003c/p\u003e \u003cp\u003e(mg/L)\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c4\"\u003e \u003cp\u003eHg in Solution after Contact with Mersorb\u0026reg;\u003c/p\u003e \u003cp\u003e(mg/L)\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c5\"\u003e \u003cp\u003ePercent Hg Removed\u003c/p\u003e \u003c/th\u003e \u003c/tr\u003e \u003c/thead\u003e \u003ctbody\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eControl V\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e500\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c3\"\u003e \u003cp\u003e520\u0026thinsp;\u0026plusmn;\u0026thinsp;104\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e-\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e0\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eControl A\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e500\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c3\"\u003e \u003cp\u003e438 \u0026plusmn; 88\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e-\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e0\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eMersorb\u0026reg; V 200\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eNA\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c3\"\u003e \u003cp\u003e520 \u0026plusmn; 104\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e10.3 \u0026plusmn; 2.1\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e98\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eMersorb\u0026reg; A 100\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eNA\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c3\"\u003e \u003cp\u003e438\u0026thinsp;\u0026plusmn;\u0026thinsp;88\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e16.4 \u0026plusmn; 3.3\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e97\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eMersorb\u0026reg; A 50\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eNA\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c3\"\u003e \u003cp\u003e438\u0026thinsp;\u0026plusmn;\u0026thinsp;88\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e13.8 \u0026plusmn; 2.8\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e97\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eMersorb\u0026reg; A 25\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eNA\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c3\"\u003e \u003cp\u003e438 \u0026plusmn; 88\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e57.8 \u0026plusmn; 11.6\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e87\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003c/tbody\u003e \u003c/colgroup\u003e \u003c/table\u003e\u003c/div\u003e \u003c/p\u003e \u003cp\u003eThe elemental compositions of the spiked test solution before and after contact with Mersorb\u0026reg; were measured by inductively coupled plasma \u0026ndash; atomic emission spectroscopy (ICP-AES). Ion chromatography (IC) was used to measure the concentrations of nitrate and nitrate in these solutions. The results are presented in Table\u0026nbsp;\u003cspan refid=\"Tab7\" class=\"InternalRef\"\u003e7\u003c/span\u003e.\u003c/p\u003e \u003cp\u003e \u003cdiv class=\"gridtable\"\u003e\u003ctable float=\"Yes\" id=\"Tab7\" border=\"1\"\u003e \u003ccaption language=\"En\"\u003e \u003cdiv class=\"CaptionNumber\"\u003eTable 7\u003c/div\u003e \u003cdiv class=\"CaptionContent\"\u003e \u003cp\u003eChange in dissolved species in solution before and after Mersorb\u003csup\u003e\u0026reg;\u003c/sup\u003e contact\u003c/p\u003e \u003c/div\u003e \u003c/caption\u003e \u003ccolgroup cols=\"3\"\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c1\" colnum=\"1\"\u003e\u003c/div\u003e \u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c2\" colnum=\"2\"\u003e\u003c/div\u003e \u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c3\" colnum=\"3\"\u003e\u003c/div\u003e \u003cthead\u003e \u003ctr\u003e \u003cth align=\"left\" colname=\"c1\"\u003e \u003cp\u003eDissolved Species\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c2\"\u003e \u003cp\u003eInitial Test Solution (mg/L)\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c3\"\u003e \u003cp\u003eSolution after Contact with Mersorb\u0026reg; (mg/L)\u003c/p\u003e \u003c/th\u003e \u003c/tr\u003e \u003c/thead\u003e \u003ctbody\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eAl\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e4430\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e4385\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eK\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e370\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e367\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eNa\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e116000\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e116500\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eP\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e362\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e360\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eS\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e1735\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e1870\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eNO\u003csub\u003e3\u003c/sub\u003e\u003csup\u003e\u0026minus;\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e151000\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e98600\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eNO\u003csub\u003e2\u003c/sub\u003e\u003csup\u003e\u0026minus;\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e24850\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e24350\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003c/tbody\u003e \u003c/colgroup\u003e \u003c/table\u003e\u003c/div\u003e \u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec9\" class=\"Section2\"\u003e \u003ch2\u003eSequestration of inorganic and organic mercury by slag\u003c/h2\u003e \u003cp\u003eIn this series of sequestration experiments sequestration of both inorganic ionic mercury added as Hg(NO\u003csub\u003e3\u003c/sub\u003e)\u003csub\u003e2\u003c/sub\u003e and organic mercury added as a 1M solution of MeHgOH were evaluated. One gram of slag was used as the sequestration reagent. After contact for 24 hours, the solutions were sampled and analyzed for total mercury and mercury species using three different methods to identify speciation: total mercury by DMA, methylmercury by gas chromatography, and inorganic ionic mercury by stannous chloride reduction. Mercury speciation was not determined for the initial and final B1 samples because they were spiked with only inorganic mercury, Hg(NO\u003csub\u003e3\u003c/sub\u003e)\u003csub\u003e2\u003c/sub\u003e. The total Hg sequestered in each sample was calculated according to Eq.\u0026nbsp;1, showing a sample calculation for B1. Results are provided in Table\u0026nbsp;\u003cspan refid=\"Tab8\" class=\"InternalRef\"\u003e8\u003c/span\u003e. The uncertainty of the DMA measurement for these analyses was reported to be 15%, and the uncertainty of the individual species measurement was 10%. (White, Brown et al. \u003cspan citationid=\"CR19\" class=\"CitationRef\"\u003e2019\u003c/span\u003e)\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec10\" class=\"Section2\"\u003e \u003cp\u003e\u003cem\u003eEquation 1\u003c/em\u003e: \u003cspan class=\"InlineEquation\"\u003e\u003cspan class=\"mathinline\"\u003e\\(\\% Removed= \\frac{{C}_{Initial}-{C}_{Final}}{{C}_{Initial}}=\\frac{76.3 - 21.1}{76.3}=72.3\\%\\)\u003c/span\u003e\u003c/span\u003e\u003c/p\u003e \u003cp\u003e \u003cdiv class=\"gridtable\"\u003e\u003ctable float=\"Yes\" id=\"Tab8\" border=\"1\"\u003e \u003ccaption language=\"En\"\u003e \u003cdiv class=\"CaptionNumber\"\u003eTable 8\u003c/div\u003e \u003cdiv class=\"CaptionContent\"\u003e \u003cp\u003eSlag Sequestration of Organic and Inorganic Mercury\u003c/p\u003e \u003c/div\u003e \u003c/caption\u003e \u003ccolgroup cols=\"8\"\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c1\" colnum=\"1\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c2\" colnum=\"2\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c3\" colnum=\"3\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c4\" colnum=\"4\"\u003e\u003c/div\u003e \u003cdiv align=\"char\" char=\"\u0026plusmn;\" class=\"colspec\" colname=\"c5\" colnum=\"5\"\u003e\u003c/div\u003e \u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c6\" colnum=\"6\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c7\" colnum=\"7\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c8\" colnum=\"8\"\u003e\u003c/div\u003e \u003cthead\u003e \u003ctr\u003e \u003cth align=\"left\" colspan=\"2\" nameend=\"c2\" namest=\"c1\"\u003e \u003cp\u003eSample ID\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c3\"\u003e \u003cp\u003eTarget Hg\u003c/p\u003e \u003cp\u003eas MeHg (mg/L)\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c4\"\u003e \u003cp\u003eTarget Hg\u003c/p\u003e \u003cp\u003eas Hg\u003csup\u003e2+\u003c/sup\u003e\u003c/p\u003e \u003cp\u003e(mg/L)\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c5\"\u003e \u003cp\u003eTotal Measured Hg by DMA\u003c/p\u003e \u003cp\u003e(mg/L)\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c6\"\u003e \u003cp\u003ePercent Total Hg Removed\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c7\"\u003e \u003cp\u003eMeasured Hg\u003csup\u003e2+\u003c/sup\u003e\u003c/p\u003e \u003cp\u003e(mg/L)\u003csup\u003eb\u003c/sup\u003e\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c8\"\u003e \u003cp\u003eMeasured organic Hg as MeHg (mg/L)\u003csup\u003ec\u003c/sup\u003e\u003c/p\u003e \u003c/th\u003e \u003c/tr\u003e \u003c/thead\u003e \u003ctbody\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\" morerows=\"1\" rowspan=\"2\"\u003e \u003cp\u003eB1\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eInitial\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e0\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e50\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c5\"\u003e \u003cp\u003e76.3\u0026thinsp;\u0026plusmn;\u0026thinsp;11.4\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c6\" morerows=\"1\" rowspan=\"2\"\u003e \u003cp\u003e72.3\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e \u003cp\u003eNA\u003csup\u003ea\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c8\"\u003e \u003cp\u003eNA\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eFinal\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e-\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e-\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c5\"\u003e \u003cp\u003e21.1\u0026thinsp;\u0026plusmn;\u0026thinsp;3.2\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e \u003cp\u003eNA\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c8\"\u003e \u003cp\u003eNA\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\" morerows=\"1\" rowspan=\"2\"\u003e \u003cp\u003eB2\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eInitial\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e100\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e0\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c5\"\u003e \u003cp\u003e101\u0026thinsp;\u0026plusmn;\u0026thinsp;15\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c6\" morerows=\"1\" rowspan=\"2\"\u003e \u003cp\u003e14.9\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e \u003cp\u003e\u0026lt;\u0026thinsp;1.0\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c8\"\u003e \u003cp\u003e81.7\u0026thinsp;\u0026plusmn;\u0026thinsp;8.2\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eFinal\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e-\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e-\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c5\"\u003e \u003cp\u003e86\u0026thinsp;\u0026plusmn;\u0026thinsp;13\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e \u003cp\u003e5.55\u0026thinsp;\u0026plusmn;\u0026thinsp;0.55\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c8\"\u003e \u003cp\u003e49.5\u0026thinsp;\u0026plusmn;\u0026thinsp;5.0\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\" morerows=\"1\" rowspan=\"2\"\u003e \u003cp\u003eB3\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eInitial\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e50\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e50\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c5\"\u003e \u003cp\u003e116\u0026thinsp;\u0026plusmn;\u0026thinsp;17\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c6\" morerows=\"1\" rowspan=\"2\"\u003e \u003cp\u003e86.6\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e \u003cp\u003e42.7\u0026thinsp;\u0026plusmn;\u0026thinsp;0.43\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c8\"\u003e \u003cp\u003e40.0\u0026thinsp;\u0026plusmn;\u0026thinsp;4.0\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eFinal\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e-\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e-\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c5\"\u003e \u003cp\u003e15.6\u0026thinsp;\u0026plusmn;\u0026thinsp;2.3\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e \u003cp\u003e\u0026lt;\u0026thinsp;1.0\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c8\"\u003e \u003cp\u003e13.7\u0026thinsp;\u0026plusmn;\u0026thinsp;1.4\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\" morerows=\"1\" rowspan=\"2\"\u003e \u003cp\u003eB4\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eInitial\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e50\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e0\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c5\"\u003e \u003cp\u003e48.7\u0026thinsp;\u0026plusmn;\u0026thinsp;7.3\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c6\" morerows=\"1\" rowspan=\"2\"\u003e \u003cp\u003e12.1\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e \u003cp\u003e\u0026lt;\u0026thinsp;1.0\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c8\"\u003e \u003cp\u003e41.5\u0026thinsp;\u0026plusmn;\u0026thinsp;4.2\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eFinal\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e-\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e-\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c5\"\u003e \u003cp\u003e42.8\u0026thinsp;\u0026plusmn;\u0026thinsp;6.4\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e \u003cp\u003e4.79\u0026thinsp;\u0026plusmn;\u0026thinsp;0.48\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c8\"\u003e \u003cp\u003e18.2\u0026thinsp;\u0026plusmn;\u0026thinsp;1.8\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003c/tbody\u003e \u003c/colgroup\u003e \u003ctfoot\u003e \u003ctr\u003e\u003ctd colspan=\"8\"\u003e\u003csup\u003ea\u003c/sup\u003eNA = not analyzed\u003c/td\u003e\u003c/tr\u003e \u003ctr\u003e\u003ctd colspan=\"8\"\u003e\u003csup\u003eb\u003c/sup\u003e Stannous chloride reduction method\u003c/td\u003e\u003c/tr\u003e \u003ctr\u003e\u003ctd colspan=\"8\"\u003e\u003csup\u003ec\u003c/sup\u003ePurge and trap gas chromatography pyro atomic fluorescence\u003c/td\u003e\u003c/tr\u003e \u003c/tfoot\u003e \u003c/table\u003e\u003c/div\u003e \u003c/p\u003e \u003cp\u003eInorganic ionic mercury was detected in moderate concentrations in two test solutions that were contacted with slag, B2 and B4, even though the initial solutions were only spiked with MeHg. The initial solutions had no detectable inorganic ionic Hg. Therefore, the presence of inorganic Hg was inferred to be generated as the result of reaction of the MeHg with the slag.\u003c/p\u003e \u003cp\u003eFor three of the solutions (B2 Final, B3 Initial, and B4 Final), the total Hg concentrations calculated from the sums of the individual Hg species measured, MeHg and inorganic mercury, were less than the total measured Hg analyses by DMA. It is possible that in these samples, additional Hg species were present but not measured by the analytical methods used for this study.\u003c/p\u003e \u003c/div\u003e"},{"header":"Discussion","content":"\u003cdiv id=\"Sec12\" class=\"Section2\"\u003e \u003ch2\u003eMersorb\u0026reg; Sequestration of Organic Mercury\u003c/h2\u003e \u003cp\u003eThe capacity of Mersorb\u003cb\u003e\u0026reg;\u003c/b\u003e to remove Hg (added as MeHg) from solution in 24 hours was determined by multiplying the initial concentration of Hg in each solution by the volume of solution and then dividing by the mass of Mersorb\u003cb\u003e\u0026reg;\u003c/b\u003e in contact with that solution. Results are plotted in Fig.\u0026nbsp;\u003cspan refid=\"Fig1\" class=\"InternalRef\"\u003e1\u003c/span\u003e. The data suggest that greater than 96% of the mercury was absorbed from the simulated waste solution containing up to 0.4 g of mercury per gram of Mersorb\u0026reg;. However, the capacity of Mersorb\u0026reg; to sequester MeHg in the 24-hour exposure tests was exceeded when the concentration of mercury exceeded 0.4 g per gram of Mersorb\u0026reg;. These data extend the previously published results which reported a non-optimized Hg sequestration to Mersorb\u0026reg; value of 0.006 g Hg/1g. (Langton and Oji \u003cspan citationid=\"CR15\" class=\"CitationRef\"\u003e2021\u003c/span\u003e).\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003cp\u003eThe concentration for dissolved ions in the simulated waste solution other than mercury were affected by the 24-hour contact with Mersorb\u0026reg;, as seen in Table\u0026nbsp;\u003cspan refid=\"Tab7\" class=\"InternalRef\"\u003e7\u003c/span\u003e. The nitrate (NO\u003csub\u003e3\u003c/sub\u003e\u003csup\u003e\u0026minus;\u003c/sup\u003e) concentration decrease about 35%, from 151 g/L to 98.6 g/L, which may indicate an affinity of the nitrate ion for the activated carbon, i.e., Mersorb\u0026reg;. The total sulfur concentration increased in the solution at the end of the exposure test compared to the starting concentration. This was attributed to the dissolution of some sulfur from the Mersorb\u0026reg;. Aluminum, potassium, sodium, phosphorous, and nitrite concentrations in the test solutions did not change noticeably before and after the partitioning tests.\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec13\" class=\"Section2\"\u003e \u003ch2\u003eSlag sequestration of Inorganic and Organic Mercury\u003c/h2\u003e \u003cp\u003eOver a 24-hour period, slag was found to be much more effective in removing inorganic mercury than in removing organic mercury present from simulated waste solution. The percents of the total mercury (measured by DMA) removed from solutions B1 through B4 were calculated from analyses shown in Table\u0026nbsp;\u003cspan refid=\"Tab8\" class=\"InternalRef\"\u003e8\u003c/span\u003e and are graphically represented in Fig.\u0026nbsp;\u003cspan refid=\"Fig2\" class=\"InternalRef\"\u003e2\u003c/span\u003e. Inorganic mercury sequestration by slag is faster with in a 24-hour experiment than that of organic methylmercury reaction with slag.\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003cp\u003eAfter 24-hour exposure testing, inorganic mercury was detected in solutions, B2 and B4, which initially contained only MeHg as shown in Fig.\u0026nbsp;\u003cspan refid=\"Fig3\" class=\"InternalRef\"\u003e3\u003c/span\u003e. This suggests that in the presence of slag, the MeHg decomposed to Hg\u003csup\u003e2+\u003c/sup\u003e and methane, CH\u003csub\u003e4\u003c/sub\u003e. Methane generation was also observed in a previous study in which simulated salt solution containing MeHg was contacted with either slag or sodium sulfide (Na\u003csub\u003e2\u003c/sub\u003eS) in a sealed vessel. (Duignan, Crawford et al. \u003cspan citationid=\"CR11\" class=\"CitationRef\"\u003e2020\u003c/span\u003e, Duignan, Crawford et al. \u003cspan citationid=\"CR10\" class=\"CitationRef\"\u003e2021\u003c/span\u003e) At the end of these tests, methane was detected in the gas phase inside the vessel which indicates that it was formed during the experiment. Decomposition of the Hg-CH\u003csub\u003e3\u003c/sub\u003e covalent bond to form methane was attributed to the very strong affinity of sulfur/sulfide with all forms of mercury. (Duignan, Crawford et al. \u003cspan citationid=\"CR11\" class=\"CitationRef\"\u003e2020\u003c/span\u003e, Duignan, Crawford et al. \u003cspan citationid=\"CR10\" class=\"CitationRef\"\u003e2021\u003c/span\u003e) See Eq.\u0026nbsp;2. Further support for sulfide being responsible for cleaving the Hg-CH\u003csub\u003e3\u003c/sub\u003e bond was reported in a separate study in which β-HgS (β-cinnabar) was detected in experiments involving slag and MeHg. (Oji and Langton \u003cspan citationid=\"CR17\" class=\"CitationRef\"\u003e2019\u003c/span\u003e)\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec14\" class=\"Section2\"\u003e \u003ch2\u003e\u003cem\u003eEquation 2.\u003c/em\u003e \u003cspan class=\"InlineEquation\"\u003e\u003cspan class=\"mathinline\"\u003e\\({CH}_{3}HgOH+ {S}^{2-}+ {H}_{2}O\\to \\beta HgS+ {{CH}_{4}+2 OH}^{-}\\)\u003c/span\u003e\u003c/span\u003e\u003c/h2\u003e \u003cp\u003eThe Hg-methyl bond (Hg-CH\u003csub\u003e3\u003c/sub\u003e) is more covalent and therefore more difficult to cleave than the Hg-hydroxyl (Hg-OH) bond. See Eq.\u0026nbsp;3. The direct sequestration of inorganic mercury by sulfide can be represented by the following reaction.\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec15\" class=\"Section2\"\u003e \u003ch2\u003eEquation 3. \u003cspan class=\"InlineEquation\"\u003e\u003cspan class=\"mathinline\"\u003e\\({Hg\\left(OH\\right)}_{2}+ {S}^{2-}\\to \\beta HgS+ {2 OH}^{-}\\)\u003c/span\u003e\u003c/span\u003e\u003c/h2\u003e \u003cp\u003e \u003c/p\u003e \u003c/div\u003e"},{"header":"Conclusions","content":"\u003cp\u003eRadioactive waste solution containing soluble mercury is currently solidified and stabilized in a cementitious waste form. The solution contains inorganic Hg\u003csup\u003e2+\u003c/sup\u003e, organic mercury species primarily MeHg, and Hg\u003csup\u003e0\u003c/sup\u003e. This waste solution is solidified/stabilized in a cementitious waste form containing ground granulated blast furnace slag as the primary reagent. To date, slag has been instrumental in stabilizing all mercury species in the waste. As the slag hydrates sulfide is released from the slag and becomes available to react with soluble mercury. The reaction results in precipitation of nanocrystals of insoluble β-cinnabar, HgS. (Oji and Langton \u003cspan citationid=\"CR17\" class=\"CitationRef\"\u003e2019\u003c/span\u003e) The resulting waste form is classified as nonhazardous for Hg. Recent analyses of the waste solution indicate the increasing concentrations of organic mercury.\u003c/p\u003e \u003cp\u003eExperiments were conducted to investigate the efficiency of organic methylmercury sequestration by Mersorb\u0026reg;, a commercial Hg sequestration product, which is porous granular activated carbon impregnated with sulfur. Mersorb\u0026reg; removed at least 96% of the methylmercury in simulated tank waste when the mass ratio of Mersorb\u0026reg; to mercury was above 2.5. These results indicate relatively small additions of Mersorb\u0026reg; can be very effective in sequestering MeHg from salt solution.\u003c/p\u003e \u003cp\u003eExperiments were also conducted to identify the reaction mechanism involved in organic and inorganic mercury sequestration by slag. Methylmercury in the simulated waste solution was determined to decompose to methane (CH\u003csub\u003e4\u003c/sub\u003e) and Hg\u003csup\u003e2+\u003c/sup\u003e in test solutions containing slag. The mercury then precipitated as β-cinnabar, HgS, which is consistent with the previous work in which methane was detected when organic mercury in tank waste was sequestered in a sealed vessel. (Duignan, Crawford et al. \u003cspan citationid=\"CR11\" class=\"CitationRef\"\u003e2020\u003c/span\u003e)\u003c/p\u003e \u003cp\u003eIn 24-hour exposure tests, slag sequestered inorganic mercury faster than MeHg because the chemical bond between carbon-mercury needed to be broken before the mercuric ion could react with the sulfide ion to precipitate HgS.\u003c/p\u003e"},{"header":"Declarations","content":"\u003cp\u003eThis work was funded by the US Department of Energy Environmental Management, Technology Development Office, Project 221818. The authors acknowledge A J Boggess for providing mercury analyses support.\u003c/p\u003e\n\u003cp\u003e\u003cbr\u003e\u003c/p\u003e\u003cp\u003e \u003ch2\u003eCompeting Interests\u003c/h2\u003e \u003cp\u003eThe authors have no relevant financial or non-finacial interests to disclose.\u003c/p\u003e \u003c/p\u003e\u003cp\u003e \u003ch2\u003eEthics Approval\u003c/h2\u003e \u003cp\u003eNot applicable.\u003c/p\u003e \u003c/p\u003e \u003cp\u003e \u003cstrong\u003eConsent to Participate\u003c/strong\u003e \u003cp\u003e \u003cem\u003eand Consent to Publish\u003c/em\u003e \u003c/p\u003e \u003c/p\u003e\u003ch2\u003eFunding\u003c/h2\u003e \u003cp\u003eThis work was supported by the Department of Energy Office of Environmental Management, Technology Development Office (Project # HQ221818).\u003c/p\u003e\u003ch2\u003eAuthor Contributions\u003c/h2\u003e \u003cp\u003eEric McCaslin and Katie Hill contributed to the study conception, design, and experimental work. Data analysis was performed by Eric McCaslin, and the first draft of the manuscript was written by Eric McCaslin. Both authors worked on revisions of the manuscript, and read and approved the final manuscript.\u003c/p\u003e"},{"header":"References","content":"\u003col\u003e\u003cli\u003e\u003cspan\u003eArbestain MC, Rodriguez-Lado L, Bao M, Macias F (2009) Assessment of Mercury-Polluted Soils Adjacent to an Old Mercury. -Fulminate Production Plant. Applied and Environmental Soil Science\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eASTM Standard C989 (2022) Standard Specification for Slag Cement for Use in Concrete and Mortars. ASTM International, West Conshohocken, PA\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eASTM Standard C1733 (2021) Standard Test Method for Distribution Coefficients of Inorganic Species by Batch Method. ASTM International, West Conshohocken, PA\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eBannochie CJ (2013) Results for the Third Quarter 2013 Tank 50 WAC Slurry Sample. (Report No. SRNL-STI-2013-00651)\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eBannochie CJ, Crawford CL, Jackson DG, Shah HB, Jain V, Occhipinti JE, Wilmarth WR (2016) Mercury Phase II Study - Mercury Behavior across the High-Level Waste Evaporator System. (Report No. SRNL-STI-2016-00163)\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eBoggess AJ, Bannochie CJ, White TL, Jones MA, Edwards TB (2019) Methylmercury and Ethylmercury Analytical Performance in SRR Samples Measured by SRNL and Eurofins Frontier Global Sciences (Report No. SRNL-STI-2018-00250)\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eBoggess AJ, White TL, Jones MA, Edwards TB, Harris SP (2019) Development and Comparison of Purgable Mercury Values in SRR Samples Measured by SRNL and Eurofins FGS. (Report N. SRNL-STI-2019-00300)\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eConner JR (1990) Chemical fixation and solidification of hazardous wastes. Van Nostrand Reinhold, New York\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eCrawford CL, Hill KA (2021) Tank 50 Simulant Grout and Toxicity Characteristic Leaching Procedure (TCLP) Results for Methyl Mercury Waste Acceptance Criteria (WAC) Limit. (Report No. STI-2020-00468)\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eDuignan MR, Crawford CL, Restivo ML, Alexander MR, Hill KA (2021) Time Dependence of Methane Generation Rates from Saltstone. (Report No. SRNL-STI-2021-00010)\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eDuignan MR, Crawford CL, Restivo ML, Alexander MR, Hill KA, Pareizs JM (2020) Methane generation rates from tank 50 simulant with methylmercury containing saltstone grout solids. (Report No. SRNL-STI-2020-00013)\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eKrishnan SV, Gullett BK, Jozewlcz W (1994) Sorption of Elemental Mercury by Activated Carbons. Environ Sci Technol 28:1506\u0026ndash;1512\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eLambert DP, Howe AM, Woodham WH, Williams MS, Hunter SC (2019) Antifoam Development for Eliminating Flammability Hazards and Decreasing Cycle Time in the Defense Waste Processing Facility. (Report No. SRNL-STI-2019-00677)\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eLangton CA, Bannochie CJ, Oji LN, Wilmarth WR (2019) Methylmercury Retention Evaluation to Support Saltstone Waste Acceptance Criteria. (Report No. SRNL-STI-2019-00530)\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eLangton CA, Oji LN (2021) Methylmercury speciation and retention evaluation to support tank 50 and saltstone waste accepance criteria: parts 2 and 3. (Report No.SRNL-STI-2020-00496)\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eLewis GS (2012) Y-12 Mercury Task Force Files: A Guide to Record Series of the Department of Energy and its Contractors. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://ehss.energy.gov/ohre/new/findingaids/epidemiologic/oakridge1/intro.html\u003c/span\u003e\u003cspan address=\"https://ehss.energy.gov/ohre/new/findingaids/epidemiologic/oakridge1/intro.html\" targettype=\"URL\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e Accessed December 2023\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eOji LN, Langton CA (2019) Methylmercury speciation and retention evaluation to support saltstone waste acceptance criteria. (Report No. SRNL-STI-2019-00060)\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eRay JW (2017) Waste Acceptance Criteria for Aqueous Waste Sent to the Z-Area Saltstone Production Facility. Savannah River Remediation (Report No. X-SD-Z-00001, Rev 17)\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eWhite TL, Brown LW, Looney BB, Jones MA (2019) Total Mercury Analysis Comparison. (Report No. SRNL-STI-2019-00056)\u003c/span\u003e\u003c/li\u003e\u003c/ol\u003e"}],"fulltextSource":"","fullText":"","funders":[],"hasAdminPriorityOnWorkflow":false,"hasManuscriptDocX":true,"hasOptedInToPreprint":true,"hasPassedJournalQc":"","hasAnyPriority":false,"hideJournal":false,"highlight":"","institution":"","isAcceptedByJournal":true,"isAuthorSuppliedPdf":false,"isDeskRejected":"","isHiddenFromSearch":false,"isInQc":false,"isInWorkflow":true,"isPdf":false,"isPdfUpToDate":true,"isWithdrawnOrRetracted":false,"journal":{"display":true,"email":"[email protected]","identity":"environmental-science-and-pollution-research","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":false,"externalIdentity":"espr","sideBox":"Learn more about [Environmental Science and Pollution Research](https://www.springer.com/journal/11356)","snPcode":"11356","submissionUrl":"https://submission.nature.com/new-submission/11356/3","title":"Environmental Science and Pollution Research","twitterHandle":"","acdcEnabled":true,"dfaEnabled":true,"editorialSystem":"em","reportingPortfolio":"Springer Hybrid","inReviewEnabled":true,"inReviewRevisionsEnabled":false},"keywords":"Mercury, Sequestration, Low-Level Radioactive Waste, Slag, Granular Activated Carbon, Cementitious Material","lastPublishedDoi":"10.21203/rs.3.rs-4378423/v1","lastPublishedDoiUrl":"https://doi.org/10.21203/rs.3.rs-4378423/v1","license":{"name":"CC BY 4.0","url":"https://creativecommons.org/licenses/by/4.0/"},"manuscriptAbstract":"\u003cp\u003eLiquid low-level radioactive waste at the Savannah River Site contains several species of mercury, including inorganic, elemental and methylmercury. This waste is solidified and stabilized in a cementitious waste form referred to as saltstone. Soluble mercury is stabilized as β-cinnabar, HgS as the result of reaction between the mercury and sulfur present in blast furnace slag, one of the cementitious regents. In this investigation, Mersorb\u003csup\u003e\u0026reg;\u003c/sup\u003e, a commercial granular activated carbon impregnated with sulfur, was evaluated as a pretreatment to remove mercury from the solution prior to cementation. Mersorb\u003csup\u003e\u0026reg;\u003c/sup\u003e was found to remove more than 96 mass percent of the methylmercury in simulated tank waste solution when the mass ratio of Mersorb\u003csup\u003e\u0026reg;\u003c/sup\u003e to mercury was above 2.5. Slag sequestered relatively more inorganic mercury than organic mercury in simulated tank waste after 24 hours of contact. This is likely due to the mercury-carbon bond being more covalent than the mercury-oxygen bond and therefore more difficult to break and slower to form HgS.\u003c/p\u003e","manuscriptTitle":"Mercury Sequestration in Alkaline Salt Low-Level Radioactive Waste","msid":"","msnumber":"","nonDraftVersions":[{"code":1,"date":"2024-06-27 10:51:24","doi":"10.21203/rs.3.rs-4378423/v1","editorialEvents":[{"type":"communityComments","content":0},{"type":"decision","content":"Minor Revision","date":"2024-09-01T03:18:34+00:00","index":"","fulltext":""},{"type":"reviewerAgreed","content":"","date":"2024-06-11T10:44:06+00:00","index":0,"fulltext":""},{"type":"reviewersInvited","content":"","date":"2024-06-11T08:48:57+00:00","index":"","fulltext":""},{"type":"editorInvited","content":"Environmental Science and Pollution Research","date":"2024-05-27T16:13:33+00:00","index":"","fulltext":""},{"type":"editorAssigned","content":"","date":"2024-05-20T04:05:51+00:00","index":"","fulltext":""},{"type":"submitted","content":"Environmental Science and Pollution Research","date":"2024-05-16T08:37:11+00:00","index":"","fulltext":""}],"status":"published","journal":{"display":true,"email":"[email protected]","identity":"environmental-science-and-pollution-research","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":false,"externalIdentity":"espr","sideBox":"Learn more about [Environmental Science and Pollution Research](https://www.springer.com/journal/11356)","snPcode":"11356","submissionUrl":"https://submission.nature.com/new-submission/11356/3","title":"Environmental Science and Pollution Research","twitterHandle":"","acdcEnabled":true,"dfaEnabled":true,"editorialSystem":"em","reportingPortfolio":"Springer Hybrid","inReviewEnabled":true,"inReviewRevisionsEnabled":false}}],"origin":"","ownerIdentity":"6c07b7d6-22a6-40fd-9a37-d4690bd279da","owner":[],"postedDate":"June 27th, 2024","published":true,"recentEditorialEvents":[],"rejectedJournal":[],"revision":"","amendment":"","status":"published-in-journal","subjectAreas":[],"tags":[],"updatedAt":"2025-01-06T16:00:28+00:00","versionOfRecord":{"articleIdentity":"rs-4378423","link":"https://doi.org/10.1007/s11356-024-35630-7","journal":{"identity":"environmental-science-and-pollution-research","isVorOnly":false,"title":"Environmental Science and Pollution Research"},"publishedOn":"2025-01-03 15:57:14","publishedOnDateReadable":"January 3rd, 2025"},"versionCreatedAt":"2024-06-27 10:51:24","video":"","vorDoi":"10.1007/s11356-024-35630-7","vorDoiUrl":"https://doi.org/10.1007/s11356-024-35630-7","workflowStages":[]},"version":"v1","identity":"rs-4378423","journalConfig":"researchsquare"},"__N_SSP":true},"page":"/article/[identity]/[[...version]]","query":{"redirect":"/article/rs-4378423","identity":"rs-4378423","version":["v1"]},"buildId":"qtupq5eGEP_6zYnWcrvyt","isFallback":false,"isExperimentalCompile":false,"dynamicIds":[84888],"gssp":true,"scriptLoader":[]}