Permeable Reactive Barrier References Frame 1, Afiouni to Cantrell

References Afiouni through Cantrell

(zero valent unless specified)

Contaminant TestType Description/Conditions Results Reference
Fe, Ultrasound (US) TCE Batch, Column US co-applied in batch/column to remove deposits from metal surface. Column 80:20 sand/iron with 50 mesh Fe, in N2. 100 L bags with deoxygenated water introduce TCE. US extends activity in batch. t1/2 260 min > 20 PV; 3mL/min, no US. t1/2 ~ 360 min > 150 PV, 2mL/min, US. US also cleaves Cl-H. Column US probe too shallow. Special design should enhance. Afiouni, G.F., et al., 212th National ACS Meeting, Orlando, FL, 36:22-29 (1996)
Fe Nitrobenzene Batch Batch experiments to investigate nitro reduction by granular iron in model systems. Nitrobenzene (disappear in few hr) -> nitrosobenzene -> aniline Reduction by surface; diss. Fe2+ & H+ produced during corrosion. Agrawal, A. & P.G. Tratnyek, 207th ACS Nat'l Meeting, San Diego, CA, pp. 492 (1994)
Fe Nitrobenzene and Carbonate Batch

Adsorbed H2CO3 & HCO3- drives metal dissolution by:

Fe(0 )+ 2H2CO3(ads) <-> Fe2+ + 2HCO3-(ads) + H2(g)

Fe(0)+ 2HCO3-(ads) <-> Fe2+ + 2CO32-(ads) + H2(g)

Corrosion rates decrease from carbonate precipitates.

Anaerobic bicarbonate buffer, Fluka Fe, and nitrobenzene as oxidant in batch exp. Kobs declined with increased carbonate and extended exposure of metal to carbonate buffer. Gray precipitate formed and may occur throughout experiments. Agrawal, A., et al., 209th National ACS Meeting, Anaheim, CA, April 2-7, 35:720 (1995)
Fe Nitrobenzene Batch 18-20 mesh Fluka Fe turnings, sonicated in 10% HCl, washed with buffer to remove acidity or Cl . Anaerobic batch in 60 ml serum bottles with 2 g dry, sieved Fe. Rates for itrobenzene (0.035) -> nitrosobenzene (0.034) -> aniline 0.008 /min. Rates controlled by mass transfer to metal surface. Precip. of siderite on metal surface inhibited nitro reduction. Agrawal, A., P.G. Tratnyek. ES&T, 30(1):153 (1996)
Fe cis- and trans-1,2-DCE Batch 10g Fisher pretreated 40-mesh filings; SA 1.0 m^2/g. 0.20 g powdered pyrite (buffer), DI water. cis- &trans-1,2-DCE at two Ci in ZHEs, anaerobic, at 12 rpm, 22-25° C. Reduc. dechlor. & sorption; Cl- 80-85%; products: ethene, ethane; more VC in cis-. cis- not 1st order. Sorption Freundlich isotherms (trans- sorption > more soluble cis-); quasi-equil. 1.1 h. Allen-King, R.M., et al., Environ. Toxicol. Chem., 16:424-429 (1997)
Fe CCl4 Batch Aging & conc. effects of acetylene & CCl4 in Ar-purged vials w/100 mL DI H2O, 5gHCl pretreated Fisher Fe & 0.10 g powder pyrite (buffer), 20° C. Fresh systems: Fe/H2O not mixed prior to compound exposure. CT: initial pseudo-1st-order rates in fresh are 2x to 4 x > aged & faster at lower conc. Acetylene: Initial rate (0.1 to 2.0 µmol) lower in aged (1d) than fresh. Indep. of conc. in aged (3 to 7d). Fast reacting sites eliminated within few hr (precip, sorp., corr.). Allen-King, R.M., et al., 213th National ACS Meeting, San Francisco, CA, 37:147-149 (1997)
Fe Dithionite Batch, Column Batch and column with Hanford sediments to predict (1) longevity of dithionite, (2) efficiency as reductant of Fe (3) longevity and reactivity of the reduced Fe Other than initial reaction with ferric iron, primary factor promoting loss of dithionite in system was disproportionation via heterogeneous catalysis at mineral surfaces. Amonette, J., et al., In Situ Remed.: Sci. Basis for Current & Future Technol. Sym. Battelle Press, pp. 851 (1994)
Fe(II) in aquifer material Cr(IV) Batch Batch experiments using sand collected from a shallow sand and gravel aquifer. Initial conc. of Cr(VI) varied from 2 to 200 µM; Adjusted pH 4.5, 5.5, 6.5. As pH decreased (6.4 to 4.5), Cr(VI) red. increased 30 to 50 nmol/m^2 (sand); 130 to 200 (fines). For 10 fold increase, amounts red. increased 35 to 80 (sand); 130 to 1000 nmol/m^2 (fines). Anderson, L.D., et al., ES&T, 28(1):178 (1994)
Ni-Fe Wall Organics In situ Otis AFB, MA Induce fracture to fill w/ Fe filings w/ slurry mixture moving down and outward, creating series of overlapping vertical planes thus becoming a "continuous" wall. Plan for 2 parallel 50' walls, 2' apart, perpendicular to flow. Plume of 5 to 150 ppb TCE & PCE. Walls will begin 80' below surface, at top of plume to 150' for deep plumes. Appleton, E.L., ES&T, 30(12):536A (1996)
Al, Fe, Zn 11 Chlorinated Solvents Batch Al coupon size 2 x 15 x 0.2 cm, Zn & Fe coupon 2.5 x 15 x 0.1 cm. 65 ml solvent and 5 ml deionized water in 125-ml flask containing solvent and metal coupon. Reactivity accelerated when water added. Problems with Al and Zn, but not Fe corrosion in dry systems. 1,1,2-trichloroethane only structure with appreciable oxidative breakdown. Archer, W. & E. Simpson, Industrial Eng. Chem. Product R&D, 16(2):158 (1977)
Al, In, Cd, Bi, Sn, Ag, Ge, Sb, Cu, Hg, Pd, Th, Pb, Ti, Mn, Co CCl4 Batch 1 ml CCl4 heated at 200°C, sealed tubes, for 14 d using twice metal shot, powder, granules, or chips needed to complete reaction. Hexachloroethane; end products perchloroethylene, hexachloro-butadiene. Most reactive Al (100%), Ti (100%), Cd (74%), antimony (58%), In (58%), Gr (47%), Sb (33%). Archer, W.L. & M.K. Harter, Corrosion: Nat'l Assoc. of Corr. Eng. (NACE), 34(5):159 (1978)
Al 1,1,1-TCA Batch 5 ml inhibitor-containing solvent refluxed with 0.5 g of 16-32 mesh pure Al pellets in open reaction tubes. Tubes in oil bath at 7°C. Upper portion extends through a water-cooled Al block that acts as a condenser. Inhibitors compete with solvent for AlCl3 produced at micro corrosion sites by complexing the chemisorbed AlCl3 product. Resultant complex insoluble in solvent, acting as a plug covering original reaction site. Archer, W.L., Industrial Eng. Chem. Product R&D, 21:670 (1982)
Zn TCE, PCE rates; products Batch Deoxygenated water (buffered), Zn(0), PCE or TCE. Sampled for product formation. Early heterogeneous process, but initial rate does not increase linearly with increasing Ci (expected for pseudo-1st-order system), but levels off as Ci increased. Reductive elimination (RE) important in Zn(0). ~ 15% PCE -> dichloroacetylene (0.25 -> acetylene bypass VC). TCE -> acetylene(20% of original TCE); trace VC. Chloroacetylene intermed. -> acetylene preferred over VC. Manipulating RE over initial hydrogenolysis would be beneficial goal. Arnold, W.A. & A.L. Roberts, 213th National ACS Meeting. San Francisco, CA, 37:76-77 (1997)
Limestone Cr Column Limestone or sand 2 cm over 10-cm depth of soil in PVC column. Leachate passed through columns at 1 PV/24 h until breakthrough. Unamended leachate diluted to 25% and pH 4.0 or 2.5 to keep Cr in solution. ~3,000 ppm TOC upon dilution and adjusting pH to 2.5. Limestone delayed breakthrough of Cr. Retained Cr(III) more than Cr(VI). Cr retention>> Be, Cd, Fe, Ni, Zn. TOC & Fe(II) determine Cr(VI)/Cr(III). (Clay, Fe oxides better at retaining Cr). pH affects solubility of Cr and limestone. When Cr(VI) & Cr(III) in leachate, migration delayed several-fold by limestone barrier. Artiole, J. & W.H. Fuller, Journal of Environmental Quality, 8:503-510 (1979)










Hexachloro benzene (HCB)






Zinc powder ± B12 under N2. Initial conc. 2.2 mM CCl4.



Zinc powder ± B12 under N2. Initial concentration of 50 µM HCB.

Zn + B12 dechlorinated CCl4 to CH4 (50% recov). Rates slowed when B12 absent [CCl4 -> CHCl3, DCM, CM, CH4 (80% recov)].

Product pentachlorobenzene higher rates w/o B12 at 9.6 h-1 compared to 0.3 hr-1 w/ B12. B12 may compete w/ HCB for e-s.

Assaf-Anid, N. & L. Nies, 209th Nat'l ACS Meeting, April 2-7, Anaheim, CA, 35:09-811 (1995)
Metal oxide from steel manufac., Limestone Phosphorus Column, Cylinder, Reactive Wall Permeable mix 50% sand, 45% crushed limestone, 5% metal oxide in acrylic column w/ 3.3 mg/L PO4-P over 3y (1250 PV). Biofilter effluent in 0.5x0.5m cyliner 2 L/d over 133d (101 PV). Funnel-&-gate in septic plume. 7m long funnel, 1.8 long; 2 wide; 10m deep) gate for 779d. >90% effic. column & cylinder. PO4-P 0 to 0.3 mg/L in column effluent. Phosphate accumlated on oxide surfaces & precipitated as microcyrstalline hydroxyapatite. Cylinder: 3.93 to 0.14 mg/L-P; 2.50 to 0.05 mg/L-ortho P. F&G: 4 m above 2 to 3 mg/L; 0.4 m above gate 1.5 to 0.4 mg/L. Avg phosphate in wall ~ 0.19 mg P/L. Baker, M.J., et al., Internat'l Contain. Technol. Conf. & Exhib., St. Petersburg, FL, Feb 9-12, pp. 697 (1997)
Fe TCE; DCE, VC, dichloromethane Batch, Column Site groundwater from DOE Pinellas Plant. VWR coarse iron filings used for high reactivity and low cost. Batch: fast rates for TCE, DCE , VC in site GW. Dichloromethane rates very slow. Column: TCEt1/2 =36-103 min; DCE = 150-200 min. However, rapid plugging of iron by Pinellas GW. Baghel, S., et al., G. E. Corp. R&D Center for USDOE, Sandia (1995)
Zeolite, 3 media types Sr, Cs, TCE Containers, TN & OH sites 55-gal drums of Na-chabazite zeolite (remove Sr, Cs. at seep, Oak Ridge National Lab, TN) and using 3 media types (reduce TCE, Portsmouth Gas.Diff. Plant, OH). >99.9% Sr, Cs removal ORNL (25% red. total radioactive discharge). TCE reduced at PORTS X-120 site. Drums predict flow and allow easy media replacement and monitoring. Barton, W., et al., Internat'l Contain. Technol. Conf. & Exhib., St. Petersburg, FL, Feb 9-12, pp. 827 (1997)
Mixture organics, sulphate reducing bacteria Acid Mine Drainage Reactive Wall, Ontario Wall installed at the Nickel Rim mine site near Sudbury, Ontario. (8/95) 15 m long perpendicular to GW flow, 3.6m deep, 4m thick. Used municipal & leaf compost, wood chips, and pea gravel (for permeability). Sand buffer, clay cap. Mon. wells parallel to GW flow. After 9 mo sulfate reduction and metal sulfide precipitation. Sulfate: 2400 to 4600 mg/L to 200 to 3600 mg/L, Fe:250 to 1300 mg/L to 1 and 40 mg/L; pH 5.8 to 7.0. Alkalinity rose 60-220 to 850-2700 mg/L as CaCO3. Fe mono-sulfide precipitate. Cost ~ $30,000.00 (half materials/half installation) potential life 15 y. Benner, S.G., et al.,
(1) ACS Meeting, San Fran., CA, April 13-17, 140 (1997)
(2) Internat'l Contain. Technol. Conf. & Exhib, St. Petersburg, FL, 835 (1997)
(3) GWMR, Fall, 99-107 (1997)
Fe Cr Reac. Wall Eliz. City, NC Model indicates reactive barrier most eff./cost effective at Eliz. City, NC. 46m long x 0.6m wide x 7.3m deep barrier installed < 6 h using continuous trencher 6/22/96. 11/96 sampling indicated 2.5 mg/L Cr(VI) declined to < MCL within barrier. Further sampling underway determining groundwater chemistry and organic concentrations. Bennett, T.A., et al., 213th National ACS Meeting, San Francisco, CA, April 13-17, pp. 243-245 (1997)
Fe Solubilized PCE Hydroxypropy l-b-cyclodextrin (HP- beta-CD) Batch, Column Batch: 100 mesh Fisher Fe powder & -8 to 50 mesh Peerless mix. 40 ml sealed vials, 10 g Fe, PCE, 40 mg/L CaCO3; 0, 45, 70 g/L HP-b-CD. Column: 0.47m x 5cm, 15 cm 70/100 mesh sand below (30-cm head) 10 m 30/40 mesh sand. 25 mL PCE to form pool. Ret. time 25.3 h. HP-b-CD enhances solubility w/o decreasing interfacial tension of PCE and water. Smaller % PCE degrad. at higher HP-b-CD conc. PCE decreased in both non-recycling and recyling of post treatment effluent. Greater degradation at higher iron SA. Plan to use higher Fe SA and longer res. times to increase degradation. Bizzigotti, G.O., et al., ES&T, 31:472-478 (1997)
Fe Cr Batch, Column Batch: Compare 100 g siderite, pyrite, Fe(0) (~ 0.5 -1mm), chips (~ 1-5mm). Use 500 g Cr in CaCO3 DI water agitated at room temp. Column: 15 x 6.5 cm, pump tracer base upward to deter. void vol. & dispersivity of column. Batch: Fe(0) > pyrite. Column: Fe chips (remove 50% Cr < 2 h) > pyrite (w/ calcite 50% 0.5 h; no calcite 50% 1 h) > coarse Fe (50% 28 h). Chips: No Cr brkthru for 4.5 PV. Filings: No Cr > 15 PV. Remain active, little coating. Blowes, D.W. & C.J. Ptacek, Subsurface Restor. Conf., 3rd Interna'l Conf. on Ground Water Quality Res., June 21-24, Dallas, TX, 214-216 (1992)
Pyrite or Fe Cr(VI), U, etc Trench Excavate trench, fill with active material such as pyrite or elemental iron to transform & precipitate contaminant. This patent relates to the treatment of groundwater for the purpose of removing water-borne contaminants. Blowes, D.W. & C.J. Ptacek, Patent 5,362,394 (1994)
Mixed organics, bacteria Nitrate - Tile Drainage In-Line Bioreactor Two 200-L fixed-bed bioreactors, with coarse sand and organic carbon (tree bark, wood chips and leaf compost), to treat 3-6 mg/L NO3 -N from farm-field drainage tile. Reduced NO3-N to < 0.02 mg/L at 10-60 L/day over a 1-yr period by anaerobic denitrification promoted by organic carbon. Design is simple, economical and maintenance free. Blowes, D.W., et al., Journal of Contaminant Hydrology 15:207-221 (1994)
Fe Cr(VI) Batch, Column Batch: 100 g (50% fine Fe filings, 49% sand, 1% calcite), Cr(VI). 2nd mix 50:50 Fe quartz. Column: 50% Fe(0). 50% sand, top 5 cm 1% calcite. 20 mg/L Cr(VI) in sim. GW. Cr(VI) 25 to <0.05 mg/L 3hr batch. No breakthrough Cr after 140 PV. Diss. & total Cr <0.05 mg/L. Fe(III) oxyhydroxides form, but not sufficient to inhibit Cr(VI) reduction at experimental velocity. Blowes, D.W, et al., 209th National ACS Meeting, Anaheim, CA, April 2-7, 35:780 (1995)
Fe Sulfate Test Reactive Wall Test cell 1.5 long x 1 wide x 1 m deep installed 10/93 in sand aquifer ~ 75 m downgrad. tailings impoundment. Organics (leaf, pine mulch, bark), creek sediment (sulfate-red. bacteria), limestone,coarse sand and gravel. 1 m along flow path, sulfate 3500 to 7 mg/L, Fe 1000 to < 5 mg/l, pH & alkalinity increased from sulfate reduction. Sulfate-reducing reactive walls are potentially effective and economical solution to many acid mine drainage problems. Blowes, D.W., et al., Mining & Environ. Conf., CANMET. Sudbury, Ontario, May 28 to June 1, 3:979 (1995)
Fe Cr(VI), TCE Fe Reactive Wall Wall of 100% Fe filings 46 m long, 0.6 m wide, 7.3 m deep installed in <6 hours using a continuous trenching technique at Elizabeth City, NC 6/96. Bench lab studies, and flow and transport models used in wall design. Site GW, reactive materials: Cr(VI) 11 to < 0.01 mg/L and TCE 1700 µg/L to < 1 µg/L. Decrease of Cr(VI) from influent 6 mg/L to < 0.01 mg/L and TCE from 5600 µg/L to 5.3 µg/L within wall. TCE approaches or attains the MCL within the barrier. Blowes, D.W., et al., Internat'l Contain. Tech. Conf. & Exhib. St. Petersburg, FL, Feb 9-12, pp. 851 (1997)
Fe Cr(VI) Batch, Column Batch: 500g Cr(VI) to 100g solid mixes [siderite, pyrite, coarse & fine Fe(0)] in open flasks, agitated, room temp. Settle 5 min; 10 mL sampled. Column: 6-6.5 cm dia. acrylic, 5-15 cm long, 1-20 cm long with layers of reactive mix. Void vol. & dispersivity determined. Cr(VI) solution introduced. Batch Rate for Cr(VI): fine Fe(0) > pyrite & coarse Fe(0). Column: partial Cr(VI) by pyrite & coarse Fe(0); quantitative Cr(VI) by fine Fe(0) at rapid velocities. Fe(0) reduces Cr(VI) to Cr(III) with oxidation to Fe(II) & Fe(III), & sparingly sol. (oxy)hydroxide precip. Cr(III) forms solid solution or adsorbs on goethite. Blowes, D.W., et al., ES&T, 31:3348-3357 (1997)
Fe CCl4, CH2Cl2 Open circuit potential time measurements using Fe with CT & DCM in borate buffer and simulated GW of KBr & CaCO3. Polarization of Fe electrode in borate solution to which 0.2 mL of CT added. CT acts as an oxidizer of Fe electrode, while DCM does not. Injection of CT faster and larger potential shifts in Fe than in freshly cleaned Fe electrode. Potential decay in all GW studies. Magnitude depended on pH and solution. Borate and KBr decay mainly from chemical dissolution of films. In CaCO3, autoreduction/ chemical dissolution may be responsible. Bonin, P.M.L., et al., 213th National ACS Meeting, San Francisco, CA, 37:86-88 (1997)
Sn, Zn & Mg CCl4 Batch Vaporization procedure (SMAD or cyro method) to compare metal powders. H2O oxidation overwhelmed Mg-CCl4 reaction. Sn, Zn degrade CCl4 but differ in carbon product. Zn yields CH4; Sn yields CO2. Boronina, T., et al., ES&T, 29:1511 (1995)
Steel wool Tc99 Column Simulated process & GW from DOE uranium enrichment plants. Packed column of steel wool, Dowex TM 1-X8. Use of iron economical but may be difficult to accurately predict its sorptive capacity or functional "lifetime" Bostick, W., et al., Oak Ridge K-25 Site Rep. Martin Marietta. DOE K/TCD-1141 (1995)





Iron oxide aggregate

Cd, Mg, Ni, TcO4-, UO22+




Batch Shake solid w/ soln 16-24 hrs in sealed container. Exp 2: 0.01, 0.03, or 1.0-g iron to 10ml w/ 8 mg/L U, shake 18 hrs, sample day 1 & 30. Exp 3: 1.43 x 0.15 cm iron coupons in 500-ml bottle w/ 927-mg/L U. N2 purge.

Iron surfaces passivate at elevated pH (little activity at >9.5). Sorption to iron corrosion products predominant removal process for uranyl (Cd, Mn and Ni also). Sorbed products need to be controlled. Columns needed to determine long-term capacity.


Fe(0)w/ sand or pelletized Fe oxide most effective. Reduces cementation from rust; enhances dilution of hydroxyl ion rxn product; enhances sorption of cationic contam. to pelletized Fe.

Bostick, W., et al., Oak Ridge & Martin Marietta Energy Systems, Inc. for
U.S. DOE. K/TSO-35P (1996)
Fe U Batch Batch: ~1.4 x 0.16 cm Fe coupons, simulated GW, soluble U as uranyl nitrate. Gas glove box. Pure O2 added to yield equivalent to solution purged with lab air. Under oxic conditions, U(VI) rapidly and strongly sorbed to hydrous ferric oxide particulate ("rust"), whereas U slowly and incompletely reduced to U(IV) under anoxic conditions. Bostick, W.D., et al., Internat'l Contain. Technol. Conf. & Exhib, St. Petersburg, FL, Feb 9-12, pp. 767 (1997)
Iron filings/pyrite TCE, PCE Batch 4-15 mL vials, anaerobic: 2 controls/2 Fe+pyrite (5g pre-treated Fe filings, 0.1 g ground pyrite [buffer]). Reaction orders 2.7 TCE & 1.3 PCE total system conc. Nonlinear sorption and fit generalized Langmuir isotherm. 1st order rates. Burris, D.R., et al., ES&T, 29:2850 (1995)
Fe PCE Batch 15 ml serum vials, 5 g iron, 0.1 g pyrite (ground). Pyrite added to stabilize the pH to 6.5 - 7.0. Anaerobic Rapid initial rate followed by a slower rate. Sorption of PCE to Fe(0) follows Langmuir-type isotherm. Campbell, T.J. & D.R. Burris. 209th Nat'l ACS Meeting, Anaheim, CA, 35:775 (1995)
Fe UO2 2+, MoO4 2-, TcO4-, CrO4 2- Batch Kinetic studies in 50 ml redox-sensitive-metal solutions added to polystyrene centrifuge tubes containing 1 g 40 mesh metallic iron with surface area of 2.43 m^2/g. Particulate Fe(0) effectively removed each of the contaminants from solution by reductive precipitation. Removal rates decreased by CrO42- > TcO4- > UO22+ >> MoO42-. Cantrell, K.J., et al., J. of Haz. Mat., 42:201 (1995)
Fe(0) Colloids Barriers Various Batch 0.2% Fe colloids, surfactant. Polymers [vinyl (VP), vio (GX), cellulose(CMC )] tested to increase colloidal Fe(0) mobility in porous media. Tubidimeter measured Fe colloids. VP superior to GX and CMC because VP suspension produced the lowest back pressure, resulting in the highest hydraulic conductivities. Cantrell, K.J., et al., J. of Environ. Eng.-ASCE, 23:786 (1997)

Fe(0) Colloids Barriers



1m columns, 4.4 cm dia. 20-30 mesh sand avg. n = .32. Fe(0) colloid dia. = 2 µm, bulk devsity = 2.25 g/cm^3, particle den. = 7.6 g/cm^3. Vel. 0.154, 0.307, 0.614 cm/s. 0.01M CaCl2 at 0.2 cm/min (~2 pore vol.) to simulate GW influx. Colloidal-size Fe(0) injected into porous media forming chemically reactive barriers. Relatively even distribuitons of Fe(0) in sand column at low conc; high injection rates. As volume increased distribution of Fe(0) colloids became increasingly even. Cantrell, K.J. & D.I. Kaplan, J. of Environ. Engineering-ASCE 123:499-505 (1997)

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.