Controlled Sulfidation to Optimize the Remediation Performance of Zerovalent Iron and Related Materials

Transcription

1 Controlled Sulfidation to Optimize the Remediation Performance of Zerovalent Iron and Related Materials Tersus 2018 Webinar Series Thu, June 21, 2018 Presenter: Ying Lan, Ph.D. Ying Lan, Paul G. Tratnyek, Richard L. Johnson Oregon Health & Science University, Portland, OR Dimin Fan Perfessional, Geosyntec, Columbia, MD Ariel Nunez Garcia, Denis M. O Carroll University of New South Wales, Sydney, Australia Jan Filip Palacký University, Olomouc, Czech Republic Abinash Agrawal Wright State University, Dayton, OH

2 Outline Growing interest in sulfur with ironbased materials. Fundamentals of sulfidation: Definition Synthesis Process and mechanisms Characterization of sulfidated zero-valent iron (ZVI). Effects on contaminant transformation. Metals and metalloids Organic contaminants Implications for groundwater remediation and water treatment. Frequently asked questions: State of the technology transfer Biogeochemical sulfidation application Effect of sulfidation on magnetic susceptibility OHSU SERDP project highlights. Emerging core concepts of abiotic natural attenuation Field assessment of abiotic natural attenuation rates 1

3 Growing Interest in Sulfur with Iron-based Materials Dechlorination by FeS ( ) Abiotic Reduction by FeS ( ) Dechlorination and Regeneration of FeS ( ) Revised from Lan, Ying, PhD dissertation, University of Oklahoma,

4 Growing Interest in Sulfur with Iron-based Materials Dechlorination by FeS ( ) Early work on sulfur with iron ( ) Recent studies on sulfidation ( ) Now, 3-4 more per month 3

5 Sulfidation of Iron-Based Materials (A Review) in ES&T To get our latest Sulfidation Review in Environmental Science & Technology, scan this QR code: 4

6 Fundamentals of Sulfidation Definition Inclusive: Modification or transformation of a metal-based material by exposure to sulfur compounds of various oxidation states. Synthesis methods Timing: Concerted vs. sequential precipitation. Conditions: aqueous-solid, aqueous-aqueous, solid-solid, gas-solid. Agents: sulfate, sulfur dioxide, dithionite, thiosulfate, elemental sulfur, sulfide. Sulfidation Conditions Sulfidation Agent Material Sulfidated Aqueous-solid Sulfide S 2- (-II) nzvi Aqueous-solid Aqueous-aqueous Solid-solid Dithionite S 2 O 4 2- (+III) Dithionite S 2 O 4 2- (+III) Elemental sulfur S 0 (0) nzvi nzvi mzvi Gas-solid Sulfur dioxide SO 2 (+IV) nzvi Fan, D., et al. (2017). Environ Sci Technol, 51(22),

7 Fundamentals of Sulfidation Definition Inclusive: Modification or transformation of a metal-based material by exposure to sulfur compounds of various oxidation states. Synthesis methods Timing: Concerted vs. sequential precipitation. Conditions: aqueous-solid, aqueous-aqueous, solid-solid, gas-solid. Agents: sulfate, sulfur dioxide, dithionite, thiosulfate, elemental sulfur, sulfide. Mechanisms Redox process at the aqueous-solid interface: sulfur induced corrosion, later forms a thin layer of FeS. ZVI core with FeO x shell Sulfur S-ZVI ZVI FeO X FeS Fan, D., et al. (2017). Environ Sci Technol, 51(22),

8 Characterization of Sulfidated ZVI and Related Materials Major operational variables: Condition S/Fe ratio Duration Exposure time S/Fe = 0.05 t = 10 min S/Fe = 0.11 t = 24 hr Fan, D., et al. (2017). Environ Sci Technol, 51(22),

9 Effects of Sulfidation Metals and Metalloids Sequestration Mechanisms Few studies on metal and metalloids: Pertechnatate TcO 4- (Fan et al., 2013, 2014) Cadmium Cd (Su et al., 2015) Chromium Cr (Gong et al., 2017) Mercury Hg (Höganäs, in testing) Sulfidation changes sequestration pathways Removal by (n)zvi is controlled primarily by reduction potentials. Removal by FeS is govern by the solubility of the metal-sulfide phases. Requires attention to the remobilization of sequestrated metals and metalloids. Reduction Potential at ph 7 (mv) Hg 2+ /Hg 0 Ag + /Ag 0 Sb(V)/Sb(III) Cr(VI)O 4 /Cr(OH) 3 Cu 2+ /Cu 0 UO 2 (OH) 2 /UO 2 TcO 4 /TcO HAsO /H 3 AsO 3 Pb 2+ /Pb 0 Ni 2+ /Ni 0 Cd 2+ /Cd 0 Fe 2+ /Fe 0 Zn 2+ /Zn 0 Mn 2+ /Mn 0 Non-reductive Reductive Original Species Metal Sulfide Increasing Sulfidation MnS As 2 S 3 FeS NiS ZnS CdS PbS CuS Ag 2 S HgS Sb 2 S Log (Solubility of Metal Sulfide) Fan, D., et al. (2017). Environ Sci Technol, 51(22),

10 Effects of Sulfidation Organic Contaminants Reactivity Standard kinetic model: From: k M = k SA a s Log-transform gives: log k SA = log k M log a s So, plotting log k SA vs. log k M gives contours of constant a s (specific surface area). Interpretation: 1. Pure size effect 2. Pure material and/or medium effect 3. Intrinsic real nano-size effect 4. Intrinsic sulfidation effect? 2. Pure material and/or medium effect 3. Intrinsic nano-size effect 1. Pure size effect Tratnyek et al. (2009) Int. Env. Nanotech. Conf. 9

11 Effects of Sulfidation Organic Contaminants Reactivity Meta-analysis of kinetic data for TCE: All published data for Iron, oxides, and sulfides. Total of 189 k s from 24 refs, including: Multiphase S-nZVI (Kim et al. 2011, 2013, 2014). Core-shell S-nZVI (Rajajayavel and Ghoshal, 2015). Conclusions: High purity ZVI (mzvi and nzvi) faster. Low purity ZVI and oxides slower. Sulfidated ZVI ~10-100x faster (nano, w/ TCE). mzvi Impure ZVI nzvi S-nZVI Fan, D., et al. (2017). Environ Sci Technol, 51(22),

12 Effects of Sulfidation Organic Contaminants Reactivity Meta-analysis of kinetic data for CT All published data for iron, oxides, and sulfides Total: 331 k s from 21 refs, including: Core-shell S-nZVI (Nezamabadi, Agrawal, 2016). S-ZVI (Hansson et al. 2008). S-FeO x (Hanoch et al. 2006). Conclusions: Moderate S doses increase nzvi reactivity with CT. High S doses may not. Impure ZVI mzvi FeO x nzvi S-nZVI Fan, D., et al. (2017). Environ Sci Technol, 51(22),

13 Effects of Sulfidation Organic Contaminants Reactivity Define enhancement due to treatment effect as R: R treatment = k +treatment obs k = t1/2 treatment obs t 1/2 R plot for organic contaminants: Total: 95 k s from 8 refs. Operational factors cause data to cluster by source. treatment +treatment distribute along contours. Conclusions: Sulfidation generally improves k. R TCE >> R CT. Variation with process, S/Fe ratio. TCE CT Fan, D., et al. (2017). Environ Sci Technol, 51(22),

14 Effects of Sulfidation Organic Contaminants Selectivity Challenges for conventional (n)zvi: Efficiency: Low selectivity for contaminant reduction [natural reduction demand (NRD)]. Longevity: Poor persistent of ZVI. TCE Water Advantages of sulfidation: Inhibits reduction of water to H 2. Increases (or does not inhibit) reduction of contaminants. Preserves selectivity for favorable product formation pathways. Overall increased efficiency. Possibly decreases aggregation and thereby increase particle mobility. Ethene/Ethane TCE Ethene/Ethane Sulfur H 2 Water H 2 13

15 Effects of Sulfidation Organic Contaminants Mechanistic Model Model condition: Aqueous-solid sulfidation Nano-ZVIs Arrow sizes correspond to reactivity Implications for remediation: Operational variables Fan, D., et al. (2017). Environ Sci Technol, 51(22),

16 Implications for Groundwater Remediation and Water Treatment Oxic Conditions: Oxidation and Sequestration 2 nd phase ISCR Injection of n(m)zvi Nanoparticles Ex Situ Treatments Reactive Filters In Situ Treatments Sulfidation of ZVI and Iron-based materials Anoxic Conditions: Reduction and Sequestration 1 st phase ISCR Permeable Reactive Barrier (PRB) 3 rd phase ISCR Abiotic Natural Attenuation Image (upper right) source: 15

17 Frequently Asked Questions Q1: What is the current state of technology transfer? Patents for materials/processes with sulfidation by design: Ghoshal, Subhasis (#15/097,796); Yan, Weile (#15/594,919). Other patents past and in future. Commercial available sulfidated iron-based products: SMI III (SMI Inc.): Ex situ water treatment. NANOFER 25DS (NANOIRON, s.r.o., Czech Republic, Sulfidized nzvi slurry selective towards TCE. AquaZVI (REGENESIS): Colloidal ZVI coated by FeS. Höganäs SNC (Höganäs): Capacity about 60 mg Hg/kg. Others coming soon? Existing technologies benefiting from sulfidated iron-based materials: GeoForm TM Extended Release (PeroxyChem)? Image source: City of Ripon, California, Proposition 50 Project: Integrated Nitrate and Arsenic Treatment Demonstration, ID No. P , February Jan Filip, Palacký University, Olomouc, Czech Republic. 16

18 Frequently Asked Questions Q2: How important is biogeochemical sulfidation? Permeable Reactive Barrier (PRB): Naturally sulfidated ZVI in ZVI PRBs containing S(-II). Column study simulated condition in a PRB at Altus Air Force Base, Oklahoma 1. In situ biogeochemical transformation (ISBGT): Simulates common sulfate reducing soil bacteria. Facilities the geochemical conversion of native iron minerals into FeS (i.e., S-FeO x ). Field test at Dover Air Force Base, Dover, Delaware 2 : Injection of Epson salt (MgSO 4 7H 2 O) and sodium lactate into injection wells. 1 st phase ISCR Permeable Reactive Barrier (PRB) 3 rd phase ISCR Abiotic Natural Attenuation 1. Shen, H., and Wilson, J. T Environ Sci Technol 41 (11): Kennedy, L. G., Everett, J. W., Becvar, E., and Defeo, D J Contam Hydrol 88 (1-2):

19 Frequently Asked Questions Q3: Does sulfidation affect magnetic susceptibility (MS)? Changes in MS: FeS has very little magnetic susceptibility comparing to ZVI and/or magnetite. Sulfidation should not increase MS. Changes in reactivity: Sulfidation generally improves reactivity towards contaminants. Current project at OHSU: Survey of MS of iron-based materials. Theory development of MS quantitative relationship using bench experiments and advanced-solid characterization. Validation and simulation of MS theory using computing simulation. Bench experiments of MS vs. reactivity with contaminants. Field tests of MS vs. reactivity (ER-2621). Process-based model to predict in situ remediation reactivity using the quantitative relationships between MS and ZVI. Lan and Tratnyek, in prep 18

20 Current SERDP Project at OHSU ER-2620 Emerging core concepts for assessment and enhancement of abiotic natural attenuation of groundwater contaminants Objective 1 Standard performance metrics How to quantify effect of sulfidation? Objective 2 Enhancement by activation/mediation Is sulfidation useful for enhancement? Objective 3 Assessment of reductant demand Does sulfidation promote longevity? 19

21 Current SERDP Project at OHSU ER-2621 Field assessment of abiotic attenuation rates using chemical reactivity probes and cryogenic core collection Evaluate use of Chemical Reactivity Probes (CRPs) for assessing abiotic reaction rates Use cryogenically-collect field cores and use CRPs to assess reactivity Evaluate CRPS as practical tools for determining kinetics, capacity and reductant demand 20

22 Summary Material characterization Reactivity Selectivity Implications TCE Water Ethene/Ethane H 2 Fan, D., et al. (2017). Environ Sci Technol, 51(22),

23 Acknowledgements 22

24 Thank you. Questions? To get our latest Sulfidation Review in Environmental Science & Technology, scan this QR code: Ying Lan Dimin Fan Paul Tratnyek 23