Permeable Reactive Barrier References Frame 4, Powell to Zouboulis

References Powell to Zouboulis

(zero valent unless specified)

Contaminant TestType Description/Conditions Results Reference
Fe Cr(VI) Batch, Column Geochemical effects and minerology on reducttion CrO42- by Fe(0) using stirred batch reactors and shaken batch bottles under N2 to evaluate kinetics and mechanisms. Chromate reduction rapid and complete in zero valent systems and natural aquifer material. t1/2 = 11 hours. When no aquifer material much slower and incomplete during 146 hours. Powell, R.M., M.S. Thesis, University of Oklahoma, Norman, OK (1994)
Fe Cr(VI) Batch,
Stirred Batch Reactors: under N2 with & without Eliz. City aquifer material. C0 of CrO42- = 136 to 156 mg/L. Column: First column portion of aquifer material. Second column mixture of Fe filings (7.5 g) & aquifer material (67.6 g). 6 mg/L chromate as K2CrO4 introduced at 0.05 ml/min. Rapid changes in Eh from positive to highly negative upon introduction of Fe metal. Chromate reduction slow in system with no aquifer material but rapid in system containing the natural solid phase. Eh and pH changes less dramatic in effluent from column but influent chromate effectively removed. Powell, R.M., et al., Water Environ. Fed. Conf., March, Miami, pp. 485 (1994)
Fe Cr(VI) Batch Some types of iron and aquifer material more reactive than others. Ada Iron & Metal (AI&M) & Master Builders Supply (MBS); Eliz. City, NC & Otis AFB, MA aquifer material used along with commercial Si sand. Data support conclusion that CrO42- can be reduced to Cr(III) in present of elemental iron. AI&M and Eliz City aquifer material most reactive. Suitable e- acceptors need to form appropriate couple. Mechanisms proposed. Powell, R.M., et al., ES&T, 29(8):1913 (1995)
Fe Cr(VI) Batch Aquifer materials from Elizabeth City (EC), NC and Otis AFB, MA also kaolinite and montmorillonite using simulated groundwater. Scrap iron filings from AI&M and cast iron metal chips from MBS. Coupled corrosion processes responsible for CrO42- reduc. & precipitation, w/ AI&M Fe; much greater rates than MBS Fe. Aluminosilicate dissolution proposed to increase reaction rates. Powell, R.M., et al., 209th National ACS Meeting, Anaheim, CA, April 2-7, 35:732 (1995)
Fe Cr(VI), TCE Batch Shaken batch bottle experiments were used to evaluate both the dissolution of 7 aluminosilicate minerals in the presence of Fe(0) and whether the dissolution affected the rates of chromate reduction by Fe(0). Support previous hypotheses that aluminosilicate dissolution promoted Fe corrosion reactions, hence chromate reduction, due to generation of protons. Proposed mechanisms for chromate reduction and TCE dechlorination depicted in reaction diagrams. Powell, R. M. & R. W. Puls, ES&T, 31:2244 (1997)
Fe Cr(VI) Column Fe filings w/ quartz sand, soln of 20 mg/L diss. Cr(VI), as K2CrO7, 10 m/a for > 150 PV. Flushed w/ CaCO3 solution following Cr(VI) breakthrough, anaerobic. Cr(VI) to Cr(III) incorporated in sparingly soluble solid species. Coatings of goethite w/ Cr, as Cr(III), on outermost edges Fe. Chemical and structural charac. similar to Fe2O3 and Cr2O3. Pratt, A.R., et al., ES&T 31:2492-2498 (1997)
Fe Atrazine Batch Chloride mixed w/ Hg(II) thiocyanate & Fe(III) nitrate. Thiocyanate reacts w/ Fe(III) giving red color (463 nm). 4.5 x 10^-5 M Fe2+ (w/ light) accelerates atrazine decomp. Atrazine fully decomposed at pH 1.5 under sunlight within a 2 hour period. Most important factors under light are surface area and nature of iron used. No degradation in dark. Pulgarin, C., et al., 209th National ACS Meeting, Anaheim, CA, April 2-7, 35:767 (1995)
Fe Cr(VI) Char. Study, Eliz City, NC 48 Cores at various depths. Assessed chemical speciation and distribution of Cr on contaminated soils and its leaching potential. Batch adsorption/reduction procedures used. Adsorption and reduction capacity of soils were overwhelmed permitting passage of Cr(VI). Capacity differences related to clay content & pH; less to amorphous iron oxide coating. Puls, R.W., C.J. Paul, D.A. Clark, J. Vardy.. J. of Soil Contam. 3(2):203 1994
Fe Cr(VI), DCE, TCE, VC Field Study, Eliz City, NC 25% each by vol. EC aquifer material, sand, Fe-lathe turnings (0.1-2 mm) & MBS-Fe-chips (1-10 mm > sulphur, carbon) in field test. 21 augered boreholes, 3 to 8 m bgs, were filled with the mixture. 21 monitoring wells installed Disappearance of contaminants with appearance of ferrous Fe, decrease in oxidation-reduction potential and DO with slight pH increase. Sulfide also detected downdgradient and within 30 cm of iron cylinders. Less reducing conditions downgradient. Puls, R.W., et al, 209th National ACS Meeting, Anaheim, CA, April 2-7, 35:788 (1995)
Fe Cr(VI) Field Study, Eliz City NC At Elizabeth City 2 Fe sources (AI&M, MBS) mixed with native aquifer material and 10-mesh washed sand. 20-cm dia. cylinders installed in three rows 3 to 8 m bgs, 21 total Cr to < 0.01 mg/L Signif. reductions in TCE. Siderite not detected, but Fe sulfides were. Full demonstration scheduled June 1996 of 50-long x 8-deep x 0.6-wide(m) trench of Fe(0). Puls, R., et al., 4th Great Lakes Geotech. & Geoenviron. Conf., Univ. of Illinois, pp. 23 (1996)
Fe Nitrate, Nitrite Batch Batch in unbuffered, anaerobic, DI water, 22°C, dark, HCl treated & untreated Fe(0) (>40 mesh) 69.4 g/L. Inject nitrate or nitrite[Co ~ 0.16 mM), 40 rpm. IC for NO3- and NO2- quantification, Colormetric Hauch for NH4-. 1st-order nitrate rate constants, k1, signif. increased by using pretreated Fe(0). First 12 h after pretreatment, gradual k1 decline by Cl-. k1 and k2 for nitrate and nitrite increase linearly with increase in the [Fe(0) SA] in m2/L of untreated Fe(0) turnings. Rahman, A. & A. Agrawal, 213th National ACS Meeting, 37:157-159 (1997)
Fe PCP Batch Electroytic Fe 5g/20 mL used. Influenced by preparation of metal surface by treating with HCl, PCP concentration, pH, temp, and presence of inorganic compounds. Pretreated iron improved rates (6 hrs, 60-70% PCP [2.7 x 10^-6 M] degraded). Keep pH near neutral. Some anions (e.g., Cl-) retard degradation. Results indicated poor remedial choice for PCP. Ravary, C. & E. Lipczynska Kochany, 209th National ACS Meeting, Anaheim, CA, April 2-7, 35:738 (1995)
Fe Fe corrosion Batch Fe(0) corrosion produce Fe2+, OH-, H2(g). H2 increase in sealed cells w/ Fe granules & H2O to determine rates. MBS Fe, Blend A, 50/50 mix of 10-18 & 18-32 mesh granules (C, 3.2%; Mn, 0.65%; S, 0.09%; SA, 1.5 m2g-1). H+ entry, entrapment by Fe cause interference. k initially 0.015 to 0.009 mmol kg-1 d-1 kPa-0.5 in 150 d. Saline rate 0.7 ~ 0.05 mmol of Fe kg-1d-1 at 25°C, 50% decrease in 150 d due to product buildup. Disregard first 40-200 h in rate calc. Anion effects rate in NaCl: HCO3 > SO42- > Cl-. Decrease 0.02 to 3.0 m. Reardon, E.J., ES&T, 29:2936-2945 (1995)
Fe TCE, PCE Site demo, Moffett, CA Pilot field demo, Moffett Field, Mountain View, CA 1/96. 50' long x 10' wide x 22' thick funnel- &-gate installed across TCE and PCE plume 4/96. Baseline sampling 6/96 & 9/96 positive. TCE > 1,000 ug/L upgradient reduced to NDL within first 2' of cell (gate). Demo continue until 3/98; tech. trans. report to be prepared for DOD. Naval Facilities Eng. Service Center, Enviro. Restor. Div., www.? Updated April 24, (1997)
Fe, US TCE Batch, column 5 to 20 mg/L TCE, 20-kHz US 0.16 w/cm2 in 0.5-L bag with 0 to 2.5 9 100-mesh Fe, anaerobic, 160 shakes/min.
Column: 20% Fe, 80% sand. Four Fe's: 50-mesh particles, Peerless acid-washed chips, unwashed Peerless, MBS washed chips. 43% 20-mesh; 40% 40-mesh, rest Fe dust. 15 mg/L TCE at 4.7 mL/min. US 15.9 mm-dia, auger drill bit, 15 cm long in 50-mesh Fe 50% power.
US removes corrosion from Fe surface and prolongs reactive life Sonication for 0.5 h increased rates about 12%. But rates nearly tripled to 184% after 1 h teatment. Prior to US lower half column (highest TCE conc.) t1/2 1.5 times upper seciton. After US t1/2 dropped. Lower t1/2 decrease 70; upper t1/2 22%. Reinhart, D.R., et al., Internat'l Contain. Tech. Conf. & Exhib. St. Petersburg, FL, Feb 9-12, pp. 806-813 (1997)
Fe trans-, cis-DCE Batch 25-ml sealed bottles w/ 1.7 g Fe(0) & 34 mg ground pyrite in 1.7 mL Ar-sparged DI water. SA Fe(0) 0.7 m2/g with either 6.7µL trans-DCE, 4.4 µL cis-DCE, 10 µL 1,1-DCE, 30µL VC in methanol,4 rpm. Volitiles partition into high headspace slowing further reaction and enhance accum. 2 categories of reductive dehalogenation: Hydrogenolysis (replace halogen by H+) & reductive elimination (2 halide ions released), both net transfer of 2 e-s. Haloethylenes can undergo reductive, 0-elimination to alkynes under environ. conditions. Evidence this involved in reaction of chloroethylenes with Fe(0). Roberts, A., et al., ES&T, 30:2654 (1996)
Fe DDT, DDD Batch Sealed 40-mL vials. Fe powder (0.3-3 g) with 20 mL deoxygenated buffer, pH 7, DDT or DDD dissolved in acetone, and, if needed, surfactant at 250 mg/L. Uncapped reactors flushed with N2, beads to improve mixing. Closed reactors shaken at 130 rpm at 20 ± 0.5 °C. Powdered Fe(0) dechlorinated DDT, DDD, DDE. DDT & DDE rates independent of Fe amount. Rates much higher with surfactant. e.g., DDT initial rate 1.7 ± 0.4 & 3.0 ± 0.8 day-1 (Fe SA norm. 0.016 ± 0.004 & 0.029 ± 0.008 L m-2/h-1), without & with surfactant, resp. Reactant rate limited by rate of dissolution. Sayles, G.D., et al., ES&T, 31:3448-3454 (1997)
Fe CCl4 Batch System similar to that used by Matheson and Tratnyek (1994) except with the range of Fe(0) concentration extended from 5-31 m2/L to 0.2 - 80 m2/L. Greater range of Fe(0) SA shows hyperbolic relationship. Concen. up to 80 m2/L sharp increase in rate indicating heterogeneous catalysis, electrical double layer or abrasion effects during mixing. Scherer, M.M. & P.G. Tratnyek, 209th National ACS Meeting, Anaheim, CA, April 2-7, 35:805 (1995)
Fe CCl4 Reduction kinetics Linear sweep voltammograms (LSV) of Fe(0) at 3000 rpm. Potentials set to avoid H+ evolution at more neg. than -700 mV/SHE and O2 evol. at more (+) than 800 mV/SHE. LSVs with and without CCl4. Increased negative current in CCl4 attributed to reduction of CCl4 to CHCl3. More reducing potential on Fe(0) increase rates of H2O & CCl4 reduction. However, H2O becomes increasingly larger portion. At potentials more negative than -700 mV/NHE, water reduction larger portion than CCl4 dechlorination, suggesting more reducing potential would not enhance CCl4 dechlorination rate. Scherer, M.M., et al., 214th National ACS Meeting, Las Vegas, NV, 37:247-248 (1997)
Fe CCl4 Reduction kinetics Fe(0) from 99.5% pure Fe(0) rod 3.0 mm dia., SA 0.071 cm2. Mass transport controlled by polished Fe(0) rotating disk electrode (RDE). Kinetics of CCl4 dechlorination in pH 8.4 buffer at potential which oxide film would not form. Cathodic current independent of electrode rotation rate, 1st order rate constant (kct = 2.3 x 10-5 cm s-1) < estimated rate constant for mass transfer to surface. Rate reduction of CCl4 by oxide-free Fe(0) dominated by reaction at metal-water interface. Scherer, M.M., et al., ES&T, 31:2385 (1997)
Fe, Mg Tetrachloro- ethylene Batch 4.1 g/L Fe powder in oxygen-free, pH 7 water, 50°C. TCE t1/2 = 20 days using Fe. 1,1,1-trichloroethane, 1,1 dichloroethylene, tetrachloroethylene transformed using buffered water & landfill leachate. Schreier, C.G. & M. Reinhard, Chemosphere, 29(8):1743 (1994)
Fe chlorinated ethylenes Batch Glovebox 90% N2 / 10% H2, bottles filled with iron and HEPES-buffered water (pH 7). Placed in 50° waterbath, with or without shaking. trans-DCE > TCE > PCE = cis-DCE = 1,1-DCE. Product: ethene, ethane. PCE:15-30%; VC: 50% red. Ethene/ethane ratio larger for VC. TCE intermed. of PCE. cis-DCE only intermed. of TCE. Schreier, C.G. & M. Reinhard, 209th National ACS Meeting, Anaheim, CA, April 2-7, 35:833 (1995)
Pd, H2 Chorinated ethylenes
Batch 0.5 g either 0.5% Pd-alumina or 1% Pd on granular carbon and 1% Pd PAC at 400 rpm. 5 chlorinated ethylenes removed within 10 min by 0.5 g of 0.5% Pd on alumina and 0.1 atm H2. Ethane 55-85%, ethene 5%. PCE t1/2 = 9 min. Nitrite decreased rate. Schreier, C.G. & M. Reinhard, 209th National ACS Meeting, Anaheim, CA, April 2-7, 35:749 (1995)
Fe Precipitates Column Column 100 mesh Fe powder (99% pure), 40 mg/L KBr & 120 mg/L CaCO3 solution to form precipitates at 0.23 mL/min RT ~ 13.3 h. N2 gas passed through 2nd column. Sampled after 158 and 166 PV. CaCO3 Fe form coating; no precip. on KBr Fe. Magnetite (Fe3O4) on Fe in-/effluent KBr & effluent CaCO3. In CaCO3, aragonite, poss. siderite, in addition to magnetite. Carbonate form near influent leaving remaining Fe covered by magnetite film. Schuhmacher, T., et al., 209th National ACS Meeting, Anaheim, CA, April 2-7, 35:801 (1997)
Fe &
H2, Pd, Al2O3
1 ,2-dibromo-3 chloropropane (DBCP) Batch Iron powder and H2/Pd/Al2O3. Palladium used as a catalyst with H2 gas as the reductant. Looked at both sterile (abiotic) buffered and unbuffered conditions. Fe(0) dehalogenated DBCP under sterile (abiotic) buffered & unbuffered; also, Pd w/ H2 gas as reductant in GW. pH had little effect, however, a solution with pH = 9 inhibited the reaction. Siantar, D.P., et al., 209th National ACS Meeting, Anaheim, CA, April 2-7, 35:745 (1995)
Fe &
1 ,2-dibromo-3 chloro-propane (DBCP) Batch Compared Fe(0) and H2/Pd-alumina for DBCP -> propane. 4 g of 100-200 mesh Fe powder in 125 ml glass bottle, 110 ml deox. soln, 10 µg/l DBCP, anaerobic, 400 rpm. MilliQtm (DI) water (pH 7.0) or GW (pH 8.2-8.7), some amended w/ anions and/or buffer (pH 7.0). Fe(0) in H2O DBCP t1/2 = 2.5 min; t1/2 = 41-77 min in GW. O2, NO3- slow rxn. 60 mg/l nitrate removed in 14 min. DBCP trans. in min. w/ 75 ml GW, 22.5 mg 1% Pd-alumina. Rate in GW 30% slower compared to Milli-Qtm. Slight inhibition in Milli-Qtm by SO4-, NO3-, Cl- or O2. SO32- >> inhibitory affect. Siantar, D.P., et al., Wat. Res. 30:2315 (1996)
Fe Atrazine Batch, Soil Fe(0) (10% w/w), 0.02 mg/L atrazine in batch. 20 mg 14C-atrazine in Fe(0) (20% w/w) in batch. Fe(0) (2% w/w) in soil to determine mineralization and availability of the pesticide atrazine. Removed 93% atrazine in 48 h. 5% adsorbed "readily avail."; 33% "restricted"; 2% residues. 88% 14C removed in 48 h. 6% available; 72% pool; rest bound. Fe in soil quadrupled mineralization in 120-d. 2% Fe(0) & 100 mg NO3- kg-1 increased 10X; unextractable residue > 2-X above control (no Fe(0)). Sinah, J., et al., HSRC/WERC Joint Conference on the Environment, May 20, Paper 36 (1997)
Fe TCE, DCE, VC Batch, Column Anaerobic & mildly aerobic conditions; > 25 commercial iron metals in several forms; 0.1-1325 m2/L iron metal; several groundwaters used. No signif. products from TCE batch or column. Strong Fe(0) pi- bonds may prevent DCE & VC products from desorbing. Direct reduction of adsorbed chloroethene at metal/water interface. Reduction iron oxide and oxyhydroxide not seen. Sivavec, T.M. & D.P. Horney, 209th National ACS Meeting, Anaheim, CA, April 2-7, 35:695 (1995)
Fe and FeS TCE Batch, Column Effect of FeS m2/L varying the FeS mass in batch. Columns with Fe filings, SA concentration avg. 6000 m2/L. TCE t1/2 ~40 min. Rates constant over several hundred PV even though surface of iron filings coated with FeCO3 precipitate. Sivavec, T.M. et al. Emerg. Technol. in Haz. Waste Mngt. VII, Atlanta, pp. 42-45 (1995)
Fe, Ni/Fe, Pd/Fe TCE Column Bimetallics excelerate degradation relative to untreated Fe. Column of Ni-treated granular Fe with TCE- contaminated site GW (TCE 2.1-3.3 mg/L). 1st-order TCE rates and products in > 250 PV in Fe/Ni. In 76 PV rates accelerated above untreated Fe. Catalytic dehydrohalogenation to hydrogenation caused enchancement. But, decreased until rate similar to untreated iron. Gray precipitate after 100 PV GW (250 mg/L carbonate). Fe catalysts prone to deactivation. Similar losses not shown in granular Fe(0) systems.

Sivavec, T.M., et al. Internat'l Contain. Tech. Conf. & Exhib. St. Petersburg, FL, Feb 9-12, pp. (1997)

Sivavec, T.M., et al., 213th National ACS Meeting, 37:83-85 (1997)

Fe TCA, TCE Batch, Column Iron powder for removal of TCA and TCE from waste water. 50% TCA removal from 4 h to 1 h as temperature rose 20 to 50°C. Degradation rates highly sensitive to Fe SA, significant decline at pH values in excess of 8.0. Senzaki, T. & Y. Kumagai, Kogyo Yosui, 357:2 (1988); Kogyo Yosui, 369:19 (1989); Senzaki, T., Kogyo Yosui, 391:21 (1991)
Fe Al, Cd, Co, Cr, Fe, K, Mg, Mn, Ni, Pb, Zn Electro. Cell Electrochemical cell of massive sulphide-graphite rock from mine site as cathode, scrap iron as the sacrificial anode and acidic leachate from mine site as electrolyte. Cell raised pH of ~41 L leachate from 3.0 to 5.6 with decrease in redox from >650 to <300 mV. Iron sulfate precipitate formed with a concomitant lowering of Al, Cd, Co, Cu and Ni. Shelp, G.S., et al., Applied Geochemistry, 10:705 (1996)
Fe Cd Packed Bed Packed bed of Fe sorbent supported on fine mesh stainless steel screen & teflon flakes at 0.12-0.70 cm/s. Cd(II) 5 mg/l at pH 7, flow 1.6 ml/min. ~ 8,000 bed vol. of synthetic waste treated before breakthrough of Cd(II). Smith, E. H., Emerg. Technol. in Haz. Waste Mngmt. VII, Atlanta, GA, pp. 1205 (1995)
Fe and sulfur Mo, U Batch Column Batch test of test material with synthetic U mill tailing pore fluid. The column consisted of a solids chamber and a water sampling chamber. 5 bottom chambers filled w/ FeSO4 and sand, 5 top chambers w/ lime and sand. Redox front coincided w/ precip. of ferrous iron by contact w/ Ca(OH)2. Mo & U successfully removed for 6 & 9 days, respec. U reduced to UO2 & precip of CaUO4 from elevated pH. Mo reduced to Mo3O8 or MoS2, or precip. of FeMoO4. Spangler, R.R. & S.J. Morrison, Pasco, WA, U.S. DOE Report (1991)
Funnel -and- gate Config. Model A variety of configurations simulated using FLOWNET ver. 2.0, a 2-D steady-state flow model based on dual formation of flow. 2-D model shows width of capture zone proportional to discharge through gate. Most efficient configuration is sides 180° apart, oriented perpendicular to the regional hydraulic gradient. Starr, R.C.& J.A. Cherry, Ground Water, 32(2):465 (1994)
Fe Halogen. organics Batch First environmental application, for removal of chlorinated organic compounds from aqueous solution. Catalyzed metallic iron powder was shown to degrade a wide range of halogenated organic contaminants. Sweeny, K.& J. Fischer, Patent 3,640,821 (1972); Patent 3,737,384 (1973); Patent 4,382,865 (1983)
In Situ Fe Wall VOCs Field Site, CA VOC degrad. rates by GW run through 7-ft Fe canister. 42.9 h res. time determined 2.2-ft width wall. Steel plates divided ~220 tons granular Fe in center from outer pea gravel. 4 mon. wells downgrad.; 2 piezometers upgradient. First commercial in situ iron wall treating VOCs at former semiconductor facility, CA. Design, construction from 11/94 to 1/95. Operation and regulatory issues summarized. Monitoring shows water quality objectives being met. Szerdy, F.S., et al, ASCE National Convention, Nov 12 14, Washington, D.C. pp. 245 256 (1996)
H2O2/Fe Powder Azo Dyes Batch Open batch system of 1000 mL. H2SO4 or NaOH used to adjust pH. Optimal pH 2-3, well mixed, ratio H2O2 to iron 0.001M:1 g/L H2O2/iron powder is better than the Fenton's reagent due to continuous dissolution of iron powder and dye adsorption to powder even though Fenton's reaction major decolorizing agent. Tang, W.Z. & R.Z. Chen, Chemosphere, 32(5):947-958 (1996)
Organics, inoculated w/ bacteria U Batch, Column 250 ml sealed bottles w/ organics, nutrients, pH 7.0, Shiprock bacteria. Columns w/ straw, alfalfa, sawdust, sand (25% fOC). GW 15 ml/lhr (1 d RT), 1 PV bacteria. Sulfate, nitrate, U(VI) monitored 90 d. Precipitated U(IV) crystalline UO2(s). Batch and column results support use of cellulosic substrates-as candidate barrier materials. Thombre, M.S., et al., Internat'l Contain. Tech. Conf. & Exhib. St. Petersburg, FL, Feb 9-12, pp. 744 (1997)
Steel Cr(VI) Batch Steel nuts put in barrel immersed in 2-L soln containing 90 ppm Cr(VI); rotated at 16 rpm. After 7.2 h, final Cr concentration < 0.5 µg/mL. Thornton, R.F., Patent 5,380,441 (1995)
Zn 2,3-dibromo pentane Batch Determine e- transfer during reductive dehalogenation. Evidence from stereospecificity of reductive elimination of vicinal dihalide stereoisomers synthesized in lab. meso-2,3-dibromopentene -> >95% trans-2-pentene; D,L-2,3 dibromopentane >95% cis-2-pentene. Reduction at metal surface where 2 e- transferred w/ no free radical intermediate. Totten, L.A. & A.L. Roberts, 209th National ACS Meeting, Anaheim, CA, April 2-7, 35:706 (1995)
Fe CCl4 Column 1st column:CCl4 in air-sat. DI water. All O2 consumed by Fe(0) giving anoxic downgrad.region. 2nd similar design to 1st but Fe zone longer and diluted by mixing with sand. DO reacts with Fe(0) slowing dechlorination. But, air, accelerated, maybe due to pH effect from carbonate, changes in pathway, catalytic role of Fe2+, or O2 creating active corrosion sites. Tratnyek, P.G., et al., Emerging Technol. in Haz. Waste Manag. VII. Atlanta, pp. 589 (1995)
Fe Chorinated organics Reactive transport model, kSA Average estimates of rate constants. Assume reductive dechlorination. Deviations with longer exposure due to precipitates. 1st-order predictions vulnerable to changes in mechanism or rates for less reactive constituents. Pseudo 1st-order rates normalized to Fe-SA(kSA) Solvents com pared over range of conditions. kSA varies by conc., Fe type, etc. Representative kSA's and reactive transport model calculate minimum barrier width for flow velocities and halocarbon. Tratnyek, P. G. et al., GWMR, Fall, pp. 108 (1997)
Fe PCE, TCE, cDCE, VC Column NJ site groundwater. Major VOCs- PCE </= 50 mg/l, TCE </= 3 mg/l. TDS 425-450 mg/l. 100% iron in column. t1/2 PCE, TCE, cDCE, VC = 0.5, 0.5, 1.5, 1.2 h, respectively. 2nd test similar for PCE, TCE but cDCE = 3.7 & VC 0.9 h. Corrosion increased pH & promoted precip. of CaCO3, FeCO3, FeOH2. Vogan, J.L., et al., ??? (1994)
chlorinated solvents Column Column using site water and Single Layer Analytic Element Model to evaluate treatment zones, flow velocities, and residence times. GW flow model & degradation rates to design and estimate cost for full-scale funnel-and-gate system at shallow sand aquifer (30-40 ft) at Army Ammunition Plant, MN. Vogan, J.L. et al., 87th Ann. Mtg, Air & Waste Manag. Cincinatti, OH, (1994)
Fe PCE, TCE, cDCE, VC Pilot- scale Test NJ site. Above-ground reactor influent PCE of 30 mg/l. Residdence time 1.1 days. Flow rate 0.5 gpm for 3 mo. Assumptions: Time for PCE degradation sufficient for any TCE to degrade; 10% cDCE, 1% VC from PCE & TCE degradation. Vogan, J., et al. 209th National ACS Meeting, Anaheim, CA, April 2-7, 35:800 (1995)
Fe, Zn CCl4 Batch Kinetics dependent on pH, SA of metal, CCl4 conc., buffer and solvent composition (volume fraction 2-propanol). Reduced CCl4 to chloroform in few h. Rate was 1st-order with respect to CCl4 at concentrations less than 7.5 mM. Warren, K., et al., J. of Haz. Mat., 41:217 (1995)
Fe PCE Surface chemistry XPS identified surface elements, valent state. Alfa Aesar Fe (10 x 1mm) cleaned (H2O2, hydrofluric acid, H2O). Vapor purifed PCE, adsorbed to Fe(100) by exposing 1 x 10^-7 Torr 100 s or 5 x 10^-7 Torr 200 s at room temp. PCE adsorbed to metal surface, activated by chemisorption. Cl- from e- transfer from Fe to adsorbed species. Adsorbed water can dissociate and provide H+ for C surface species from PCE dissociation. Hydrocarbon can be produced from this reaction. Wang, C.-B.& W.-X. Zhang, 213th ACS Meeting, San Francisco, CA, 37:163-164 (1997)
Organic mix, anaerobic bacteria Mine Waste Batch Sealed, glass flasks simulated mine drainage, organic mixtures, measured permeability. Consortium of bacteria from creek facilitated reducing conditions & degradation. Limestone ensured optimum pH; anaerobic conditions. Reactivity & permeability (> 10^-3 cm/s) suitable. Higher sulphate reduction rates and longer effectiveness from organic mixture. Geochemical reactive and transport models will be used to assess effectiveness in treatment of mine drainage using reactive walls. Waybrant, K. R., et al, Sudbury '95, Mining and the Environ. CANMET, Ottawa, Ontario, 3:945-953 (1995)
Methano. bacteria and Fe CHCl3 Batch Anaerobic, 200 rpm, 20°C, 25 mL, methanogenic culture, iron powder, iron filings, steel wool. CHCl3 tested in iron cell, iron-supernatant and resting cell. k = 0.11 (Fe-cell), 0.003 (Fe-supernatant ) & 0.007 hr-1 (resting cell). Biodehal. to abiotic rxns 37:1. Biocorrosion of Fe & biodehal. of CHCl3 via cometabolism using H+ from H2O. Weathers, L.J., et al., 209th Nat'l ACS Meeting, April 2-7, Anaheim, CA, 35:829 (1995)
Fe Kinetics dibromo pentane Batch Synthesized stereoisomer to demonstrate e- transfer. Experiments indicate reduction takes place at metal surface. Weber, E.J., 209th Nat'l ACS Anaheim, CA, 35:702 (1995)
Fe 4-aminoazo benzene (4 AAB) Batch 4-AAB has reactive amino group for attaching molecule to nonreactive surface. Reducing azo linkage suggest aqueous reductant, if not, then surface-mediated process. Circumvented surface mediated contact to surface of Fe(0) by adding appropriate water soluble e- mediators. Species that can function as e- mediators were found present in the soil. Weber, E.J., ES&T, 30:716 (1996)
Fe 1,2-DCE, TCE, Freon, VC Treatment Wall Granular Fe(0) & gravel at former semiconductor facility, San Francisco. GW flow 1 ft/day. 2 d RT required for VC. Wall 40' long, 20 to 7' bgs, Fe 4 ft wide allow 2 d res. time (RT). Slurry walls east and west side for hydraulic control. 4 mon. wells in wall. Yamane, C., et al., 209th Nat'l ACS Meeting, Anaheim, CA, April 2-7, 35:792 (1995)
Fe Nitrate Batch 150 ml flasks in air-dry & sat. (parafilm seal) 3 d. Samples extracted in 50 mL DI. Purged with N2.
"Artificial" soil contam. with nitrate (10 g clay + 10 g sand + 10 g Fe powder + 10 mL of 50 mg-NO3-N/l).
94.4% Nitrate-N removal (, 6% Fe(0)); 100% in 24 h (60 mg NO3--N/L ,6% Fe(0) , pH 1.0); inver. related to pH.
97% air-dry or 99% wet samples; 2% control 10 g clay + 10 g sand + 10 mL of 50 mg-NO3--N/L without Fe powder.
Zawaideh, L.L., et al., HSRC/WERC Joint Conf. on the Environment, May 20 (1997)
Nano-Fe or Pd/Fe Particles PCB, TCE Batch 50 ml 20 mg/L TCE, 1.0 g nano-Fe or Pd/Fe in 50-ml vial sealed, 30 rpm. PCBs, 50 µl 200 µg/ml Aroclor 1254 in methanol with 1 ml ethanol/water (1/9), 0.1 g wet Fe or Pd/Fe in 2-ml vial, 30 rpm 17 h. Comm. Fe tested. Syn. sub-colloidal metals. Nanoscale Fe more reactive than comm. Fe powder, due to high SA, active Fe surface, less surface coverage by iron oxide layer. Nanoscale Pd/Fe more active than pure Fe. nano-Fe inactivated by Fe oxide formation. Zhang, W.-X. & C.-B. Wang, 213th ACS Meeting, San Francisco, CA, 37:78-79 (1997)
Pyrite fines Cr(VI) Batch Pyrite fines collected near mine area. Pyrite crushed to 45 µm. Used mixed batch reactors. Pyrite found to act as efficient Cr(VI) reducing agent. The Cr(III) hydroxide precipitated onto pyrite particles. Zouboulis, A., et al., Wat. Res. 29(7):1755 (1995)

Abbreviations: PV = Pore Volume; US = Ultrasound; SA = Surface Area; GW = Groundwater; ZHE = Zero Head-Space Extractors;

MBS = Master Builders Supply; ND = Nondetectable; RT = Residence Time.