Nanoremediation

About: Nanoremediation is a research topic. Over the lifetime, 78 publications have been published within this topic receiving 8948 citations.

Nanoscale Iron Particles for Environmental Remediation: An Overview

Abstract: Nanoscale iron particles represent a new generation of environmental remediation technologies that could provide cost-effective solutions to some of the most challenging environmental cleanup problems. Nanoscale iron particles have large surface areas and high surface reactivity. Equally important, they provide enormous flexibility for in situ applications. Research has shown that nanoscale iron particles are very effective for the transformation and detoxification of a wide variety of common environmental contaminants, such as chlorinated organic solvents, organochlorine pesticides, and PCBs. Modified iron nanoparticles, such as catalyzed and supported nanoparticles have been synthesized to further enhance the speed and efficiency of remediation. In this paper, recent developments in both laboratory and pilot studies are assessed, including: (1) synthesis of nanoscale iron particles (10–100nm, >99.5% Fe) from common precursors such as Fe(II) and Fe(III); (2) reactivity of the nanoparticles towards contaminants in soil and water over extended periods of time (e.g., weeks); (3) field tests validating the injection of nanoparticles into aquifer, and (4) in situ reactions of the nanoparticles in the subsurface.

Synthesizing Nanoscale Iron Particles for Rapid and Complete Dechlorination of TCE and PCBs

Abstract: Transformation of halogenated organic compounds (HOCs) by zero-valent iron represents one of the latest innovative technologies for environmental remediation. For example, iron can be used to construct a reactive wall in the path of a contaminated groundwater plume to degrade HOCs. In this paper, an efficient method of synthesizing nanoscale (1−100 nm) iron and palladized iron particles is presented. Nanoscale particles are characterized by high surface area to volume ratios and high reactivities. BET specific surface area of the synthesized metal particles is 33.5 m2/g. In comparison, a commercially available Fe powder (<10 μm) has a specific surface area of just 0.9 m2/g. Batch studies demonstrated that these nanoscale particles can quickly and completely dechlorinate several chlorinated aliphatic compounds and a mixture of PCBs at relatively low metal to solution ratio (2−5 g/100 mL). Surface-area-normalized rate constants (KSA) are calculated to be 10−100 times higher than those of commercially availa...

Remediation of Cr(VI) and Pb(II) aqueous solutions using supported, nanoscale zero-valent iron

Abstract: Borohydride reduction of an aqueous iron salt in the presence of a support material gives supported zero-valent iron nanoparticles that are 10−30 nm in diameter. The material is stable in air once it has dried and contains 22.6% iron by weight. The supported zero-valent iron nanoparticles (“Ferragels”) rapidly separate and immobilize Cr(VI) and Pb(II) from aqueous solution, reducing the chromium to Cr(III) and the Pb to Pb(0) while oxidizing the Fe to goethite (α-FeOOH). The kinetics of the reduction reactions are complex and include an adsorption phase. About 10% of the iron in the material appears to be located at active surface sites. Once these sites have been saturated, the reduction process continues but at a much lower rate, which is likely limited by mass transfer. Rates of remediation of Cr(VI) and Pb(II) are up to 30 times higher for Ferragels than for iron filings or iron powder on a (Fe) molar basis. Over 2 months, reduction of Cr(VI) was 4.8 times greater for Ferragels than for an equal weigh...

Zero-Valent Iron Nanoparticles for Abatement of Environmental Pollutants: Materials and Engineering Aspects

Abstract: Zero-valent iron nanoparticle technology is becoming an increasingly popular choice for treatment of hazardous and toxic wastes, and for remediation of contaminated sites. In the U.S. alone, more than 20 projects have been completed since 2001. More are planned or ongoing in North America, Europe, and Asia. The diminutive size of the iron nanoparticles helps to foster effective subsurface dispersion whereas their large specific surface area corresponds to enhanced reactivity for rapid contaminant transformation. Recent innovations in nanoparticle synthesis and production have resulted in substantial cost reductions and increased availability of nanoscale zero-valent iron (nZVI) for large scale applications. In this work, methods of nZVI synthesis and characterization are highlighted. Applications of nZVI for treatment of both organic and inorganic contaminants are reviewed. Key issues related to field applications such as fate/transport and potential environmental impact are also explored.

TCE dechlorination rates, pathways, and efficiency of nanoscale iron particles with different properties.

Abstract: Nanoscale Fe0 particles are a promising technology for in situ remediation of trichloroethene (TCE) plumes and TCE-DNAPL source areas, but the physical and chemical properties controlling their reactivity are not yet understood. Here, the TCE reaction rates, pathways, and efficiency of two nanoscale Fe0 particles are measured in batch reactors: particles synthesized from sodium borohydride reduction of ferrous iron (Fe/B) and commercially available particles (RNIP). Reactivity was determined under iron-limited (high [TCE]) and excess iron (low [TCE]) conditions and with and without added H2. Particle efficiency, defined as the fraction of the Fe0 in the particles that is used to dechlorinate TCE, was determined under iron-limited conditions. Both particles had a core/shell structure and similar specific surface areas (∼30 m2/g). Using excess iron, Fe/B transformed TCE into ethane (80%) and C3−C6 coupling products (20%). The measured surface area normalized pseudo-first-order rate constant for Fe/B (1.4 ×...