{{Short description|Metallic iron}} {{Multiple issues| {{Confusing|date=October 2024}} {{Lead too short|date=October 2024}} }} thumb|upright|Venn diagram showing the overlap between ZVIs and PRBs '''Zerovalent iron''' (ZVI) describes forms of iron metal that are proposed for use in the environmental remediation of contaminated soil and groundwater.<ref>{{cite journal |last1=Fu |first1=Fenglian |last2=Dionysiou |first2=Dionysios D. |last3=Liu |first3=Hong |title=The use of zero-valent iron for groundwater remediation and wastewater treatment: A review |journal=Journal of Hazardous Materials |date=February 2014 |volume=267 |pages=194–205 |doi=10.1016/j.jhazmat.2013.12.062 |pmid=24457611 |bibcode=2014JHzM..267..194F }}</ref><ref name=Li>{{cite journal |last1=Li |first1=Xiao-qin |last2=Elliott |first2=Daniel W. |last3=Zhang |first3=Wei-xian |title=Zero-Valent Iron Nanoparticles for Abatement of Environmental Pollutants: Materials and Engineering Aspects |journal=Critical Reviews in Solid State and Materials Sciences |date=December 2006 |volume=31 |issue=4 |pages=111–122 |doi=10.1080/10408430601057611 |bibcode=2006CRSSM..31..111L }}</ref><ref>{{cite journal |last1=Stefaniuk |first1=Magdalena |last2=Oleszczuk |first2=Patryk |last3=Ok |first3=Yong Sik |title=Review on nano zerovalent iron (nZVI): From synthesis to environmental applications |journal=Chemical Engineering Journal |date=March 2016 |volume=287 |pages=618–632 |doi=10.1016/j.cej.2015.11.046 |bibcode=2016ChEnJ.287..618S }}</ref><ref name="Gillham 537">{{cite book |last1=Gillham |first1=Robert W. |last2=Vogan |first2=John |last3=Gui |first3=Lai |last4=Duchene |first4=Michael |last5=Son |first5=Jennifer |title=In Situ Remediation of Chlorinated Solvent Plumes |chapter=Iron Barrier Walls for Chlorinated Solvent Remediation |series=SERDP/ESTCP Environmental Remediation Technology |date=2010 |pages=537–571 |doi=10.1007/978-1-4419-1401-9_16 |isbn=978-1-4419-1400-2 }}</ref>

{{multiple image | align = right | footer = <div style="text-align:center;">Click either image to enlarge</div> | image1 = Iron Remediation Reaction Processes.jpg | caption1 = Model A | width1 = {{#expr: (230 * 366 / 628) round 0}} | image2 = Iron Remediation Reaction Processes II.jpg | caption2 = Model B | width2 = {{#expr: (230 * 375 / 592) round 0}} }}

ZVI operates by electron transfer from Fe<sup>0</sup> toward some organochlorine compounds, a common class of pollutants. The remediation process is proposed to generate Fe<sup>2+</sup> and Cl<sup>−</sup> and halide-free organic products, all of which are relatively innocuous.<ref name=Tratnyek>Tratnyek, Paul, and Rick Johnson. "Remediation with Iron Metal."{{verify source|date=November 2025}} Center for Groundwater Research. Oregon Health and Science University, 04 Feb. 2005.</ref> Nanoscale ZVIs (nZVIs) are commonly used in remediation of chlorinated compounds and other pollutants.<ref>{{cite journal |last1=Karn |first1=Barbara |last2=Kuiken |first2=Todd |last3=Otto |first3=Martha |title=Nanotechnology and in Situ Remediation: A Review of the Benefits and Potential Risks |journal=Environmental Health Perspectives |date=December 2009 |volume=117 |issue=12 |pages=1823–1831|doi=10.1289/ehp.0900793 |pmid=20049198 |pmc=2799454 |bibcode=2009EnvHP.117.1813K }}</ref>

==Type of ZVI== thumb|205 px|click to enlarge

*Bulk Fe. Cast iron, consisting of scrap iron of construction grade, has been used as a reactive material for permeable reactive barriers (PRB) for groundwater remediation. Reactions are generally believed to occur on the Fe (oxide) surface; however, graphite inclusions can also serve as reaction sites.<ref name=Jafarpour>{{cite journal |last1=Jafarpour |first1=Benham |last2=Imhoff |first2=Paul T. |last3=Chiu |first3=Pei C. |title=Quantification and modelling of 2,4-dinitrotoluene reduction with high-purity and cast iron |journal=Journal of Contaminant Hydrology |date=January 2005 |volume=76 |issue=1–2 |pages=87–107 |doi=10.1016/j.jconhyd.2004.08.001 |pmid=15588574 |bibcode=2005JCHyd..76...87J }}</ref> *Nanoscale Fe. In addition to using macroscale iron in PRBs, nanoparticles (1-100&nbsp;nm diameter) of zerovalent iron (nZVI) are effective.<ref name=Li/> *Zn. Zinc has shown much higher reactivity toward pentachlorophenol than iron. This indicates that zinc may be used as a replacement for ZVI in dechlorinating chlorinated phenols. Chlorinated phenols are sequentially dechlorinated and thus less-chlorinated phenols have been identified as a reduction product.<ref name=Kim>{{cite journal |last1=Kim |first1=Y-H. |last2=Carraway |first2=E. R. |title=Dechlorination of chlorinated phenols by zero valent zinc |journal=Environmental Technology |date=December 2003 |volume=24 |issue=12 |pages=1455–1463 |doi=10.1080/09593330309385690 |pmid=14977141 |bibcode=2003EnvTe..24.1455K }}</ref>

==Type of contaminants treated== Treatment of many kinds of pollutants has been proposed, but few have been demonstrated in solving environmental challenges. *Cadmium (Cd<sup>2+</sup>) is converted to immobile Cd metal.<ref>{{cite journal |last1=Boparai |first1=Hardiljeet K. |last2=Joseph |first2=Meera |last3=O’Carroll |first3=Denis M. |title=Kinetics and thermodynamics of cadmium ion removal by adsorption onto nano zerovalent iron particles |journal=Journal of Hazardous Materials |date=February 2011 |volume=186 |issue=1 |pages=458–465 |doi=10.1016/j.jhazmat.2010.11.029 |pmid=21130566 |bibcode=2011JHzM..186..458B }}</ref> *Chloramines are effectively reduced by ZVI.<ref name=Bedner>{{cite journal |last1=Bedner |first1=Mary |last2=MacCrehan |first2=William A |last3=Helz |first3=George R |title=Making chlorine greener: investigation of alternatives to sulfite for dechlorination |journal=Water Research |date=May 2004 |volume=38 |issue=10 |pages=2505–2514 |doi=10.1016/j.watres.2004.03.010 |pmid=15159154 |bibcode=2004WatRe..38.2505B }}</ref> *Nitrate reduction by iron powder is observed at pH ≤ 4.<ref name=Huang>{{cite journal |last1=Huang |first1=Chin-Pao |last2=Wang |first2=Hung-Wen |last3=Chiu |first3=Pei-Chun |title=Nitrate reduction by metallic iron |journal=Water Research |date=August 1998 |volume=32 |issue=8 |pages=2257–2264 |doi=10.1016/S0043-1354(97)00464-8 |bibcode=1998WatRe..32.2257H }}</ref> Ammonia is the end product. Using nanoscale iron, Nitrogen gas (N<sub>2</sub>) is the product.<ref name=Choe>{{cite journal |last1=Choe |first1=Seunghee |last2=Chang |first2=Yoon-Young |last3=Hwang |first3=Kyung-Yub |last4=Khim |first4=Jeehyeong |title=Kinetics of reductive denitrification by nanoscale zero-valent iron |journal=Chemosphere |date=October 2000 |volume=41 |issue=8 |pages=1307–1311 |doi=10.1016/S0045-6535(99)00506-8 |pmid=10901263 |bibcode=2000Chmsp..41.1307C }}</ref> *Nitrated aromatics are reduced by bulk iron.<ref name=Jafarpour/><ref>{{cite journal |title=2,4-DIAMINOTOLUENE |journal=Organic Syntheses |date=1931 |volume=11 |pages=32 |doi=10.15227/orgsyn.011.0032 }}</ref><ref>{{cite journal |title=o-Aminobenzaldehyde, Redox-Neutral Aminal Formation and Synthesis of Deoxyvasicinone |journal=Organic Syntheses |date=2012 |volume=89 |pages=274 |doi=10.15227/orgsyn.089.0274 }}</ref> *Chlorinated pesticides such as DDT, DDD, and DDE. The rates of dechlorination are enhanced by the surfactant Triton X-114.<ref name="Sayles">{{cite journal |last1=Sayles |first1=Gregory D. |last2=You |first2=Guanrong |last3=Wang |first3=Maoxiu |last4=Kupferle |first4=Margaret J. |title=DDT, DDD, and DDE Dechlorination by Zero-Valent Iron |journal=Environmental Science & Technology |date=December 1997 |volume=31 |issue=12 |pages=3448–3454 |doi=10.1021/es9701669 |bibcode=1997EnST...31.3448S }}</ref> *Perchloroethylene (PCE) and trichloroethylene (TCE), common industrial solvents, and their degradation products dichloroethylene (DCE) and vinyl chloride, can be reduced to ethylene and ethane using ZVI as a reagent. This can be applied to the remediation of soils contaminated with these chlorinated organic solvents, commonly found at dry cleaning facilities.<ref>{{cite journal |last1=Navarra |first1=Wanda |last2=Sacco |first2=Olga |last3=Rescigno |first3=Raffaella |last4=Daniel |first4=Christophe |last5=Vaiano |first5=Vincenzo |last6=Pisano |first6=Domenico |last7=Brancato |first7=Bruno |last8=Casertano |first8=Francesco |last9=Raiola |first9=Mario |last10=Venditto |first10=Vincenzo |title=Remediation of perchloroethylene contaminated groundwater using Fe0/ZnS embedded in a highly porous polymer: Experimental results on pilot-scale photoreactor and kinetic modeling analysis for industrial scale-up |journal=Catalysis Communications |date=July 2023 |volume=180 |article-number=106699 |doi=10.1016/j.catcom.2023.106699 |doi-access=free }}</ref>

==Notes== {{Reflist|2}}

==Further reading== * {{cite book |last1=Tratnyek |first1=Paul |editor-first1=Matthew A. |editor-last1=Tarr |title=Chemical Degradation Methods for Wastes and Pollutants |chapter=Permeable Reactive Barriers of Iron and Other Zero-Valent Metals |pages=371–421 |series=Environmental Science & Pollution |date=2003 |volume=26 |doi=10.1201/9780203912553 |isbn=978-0-8247-4307-9 }}

Category:Environmental chemistry