Download or read book Remediation of Per and Polyfluoroalkyl Substances and Comingled Chlorinated Solvents Using Reduced Graphene Oxide nanoscale Zero valent Iron written by Sushmita Regmi and published by . This book was released on 2022 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: The lack of biodegradability of PFAS, or per- and polyfluoroalkyl substances, is due to the presence of many strong carbon-fluorine bonds. Two common PFAS that are found in the environment are perfluorooctanoic acid (PFOA) and perfluorooctanesulfonic acid (PFOS). This work first studied an innovative pathway for PFAS removal through the adsorption of PFOA and PFOS (pre-concentrating the contaminants) by nanoscale zero-valent iron/reduced graphene oxide (rGO-nZVI) and their subsequent degradation via photocatalysis under UVC light. The GO that was later reduced in nanohybrid production was made utilizing a modified Hummer's method. The rGO-nZVI nanohybrid was prepared for the first time via thermal reduction at high temperatures. Additionally, the nanohybrid was prepared using the wet chemistry method for comparison. LC/MS/MS analysis was conducted to determine the adsorption efficiencies for PFOA and PFOS using the nanohybrids and their successive removal under UVC light. Chlorinated hydrocarbons are another group of contaminants of concern that should be removed from the subsurface due to their harmful effects. In this study, a more complex mixture of the contaminants including PFAS and chlorinated hydrocarbons was investigated, which is usually found in the superfund and other contaminated sites. Considering the effectiveness of nZVI to remove chlorinated hydrocarbons from the subsurface, engineered nZVI coupled with rGO was utilized to enhance the removal efficiency of the mixture of contaminants, i.e., PFAS comingled with chlorinated hydrocarbons. The synthesized rGO-nZVI nanoparticle showed high adsorption efficiencies for both PFOA and PFOS, i.e., removal of 55.3%, 98.2%, and >99.9% of PFOA of 10, 1, and 0.1 mg/L, and 94.9%, 97.6%, and 85.0% of PFOS of 10, 1, and 0.1 mg/L, respectively, in 3 h. Later degradation of pre-concentrated PFAS under UVC light was also achieved. Using extracted rGO-nZVI, 55.1%, 77.6% of preconcentrated PFOS was degraded starting from 10, and 1 mg/L of initial concentrations before adsorption in the photoreactor at the end of 24 h. In comparison, 68.5% and 47.2% of PFOS and PFOA (starting from 1 mg/L each) was degraded, respectively, using rGO-nZVI directly under UVC light after 24 h. Moreover, it was found that rGO-nZVI had high adsorption capacity of 69.4% and 68.7% respectively for TCE and PFOA in a mixture of these contaminants. Under UVC irradiation, the preconcentrated mixture of TCE and PFOA were both degraded to below the detection limit in 21 h. It was also found that PFOA concentration dropped by 64.3% at 5 h and by 88.7% at 24 h by fresh rGO-nZVI in presence of 10 mg/L TCE. Short-chained PFCAs like PFHpA and PFHxA were found as the intermediates for PFOA degradation using rGO-nZVI under UVC light. Also, under UVC irradiation of a mixture of TCE and PFOA, TCE degradation was supported by the formation of intermediates during the reaction. Because of its composition, photocatalytic activity, large surface area, magnetic properties, and environmental friendliness, the thermal reduced rGO-nZVI particle demonstrated its potential to successfully remove PFAS and comingled chlorinated hydrocarbon from pre-concentration followed by degradation under UVC light. The nanohybrid is promising to be used to repair PFAS-contaminated water bodies.

Download or read book Per and Polyfluoroalkyl Substances PFAS Degradation by Nanoscale Zero valent Iron Under Light for Water Reuse written by Chunjie Xia and published by . This book was released on 2022 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: Wastewater reclamation and reuse have been increasingly practiced as sustainable strategies to meet water demands, particularly in regions threatened by water shortages. However, one of the biggest challenges for reusing wastewater effluents (WEs) as irrigation water is to remove emerging organic contaminants such as persistent and potentially bioaccumulated per- and polyfluoroalkyl substances (PFAS), whose presence may result in adverse impacts on crops, soils, aqueous ecosystems, and human health. Photocatalysis is an effective and promising technique to remediate PFAS in aqueous media. This dissertation aims to: i) Develop a novel, environmental-friendly, and low-cost treatment process for PFAS removal and degradation for water reuse; ii) Optimize the experimental conditions and investigate the removal mechanisms of PFAS with different structures in this novel process; iii) Scale up this treatment process and apply it to treatment of WEs in a point-of-use (POU) system. First, ultraviolet (UV) C /nanoscale zero-valent iron (nZVI, Fe0 nanoparticles (NPs)) system is used for the first time to induce PFAS photocatalytic removal from aqueous solution. Oxidative and/or reductive degradation of three representative PFAS - perfluorooctanoic acid (PFOA), perfluorononanoic acid (PFNA), and perfluorooctane sulfonate (PFOS) was achieved using Fe0 NPs under UVC light both with and without presence of oxygen. However, no PFAS removal was observed either under visible light and in the dark, and much lower PFAS degradation was achieved under UVA light. Higher degradation and defluorination efficiencies were obtained for longer chain PFNA compared to PFOA, and higher degradation and defluorination of PFAS were achieved without presence of O2 compared to with O2. The degradation of PFOA and PFOS followed first order reaction kinetics with the highest efficiencies achieved of 97.6, >99.9, and 98.5% without presence of O2 for PFOA, PFNA, and PFOS, respectively. The degradation efficiencies increased with the increase of nZVI concentrations in the range of 1-100 mg/L. The degradation efficiency of PFOA using bare Fe0 NPs was higher than that using 1% PVP-coated Fe0 NPs in the initial 6 h. Second, the removal mechanism of PFAS in UVC/Fe0 NPs system was obtained by testing the concentrations of iron ions (Fe2+/Fe3+), intermediate products, and reactive oxygen species (ROS, e.g., ·O2- and ·OH) generated, and conducting ROS quenching experiments. The proposed degradation pathway of PFCAs (PFNA and PFOA) was initiated from PFOA/PFNA oxidation by transferring an electron of the carboxylate terminal group of PFOA/PFNA to the Fe(III)-carboxylate complex, then followed by decarboxylation−hydroxylation−elimination−hydrolysis (DHEH) pathway and the accompanying CO2 and F− release. The generated shorter chain PFCAs also underwent degradation with time in the system. This proposed degradation pathway was confirmed by the formation of shorter chain PFCAs, e.g. PFHpA, PFHxA, PFPeA, and PFBA, F- ions, and rapid consumption of Fe3+. For PFOS, besides H/F exchange pathway and chain-shortening (DHEH pathway) to form short chain PFAS during PFCA degradation, desulfonation to form PFOA followed by PFOA degradation also happened. These pathways were suggested by the formation of intermediates -- trace amount of shorter chain PFCAs, 6:2 FTS, PFHpS, and F- ions. ·O2- and ·OH were not involved in PFOA degradation in the UVC/Fe0 NPs system with presence of O2, while they may be involved in PFOS degradation, e.g., desulfonation to form PFOA, which were suggested by the results of quenching experiments. And introducing H2O2 into the UVC/Fe0 NPs system resulted in lower PFOA degradation efficiency and defluorination efficiency, which also indicated that ·OH may not be involved in PFOA degradation. Hydrated electrons e-aq that can be involved in desulfonation, defluorination, and C-C bond scission processes were likely quenched by the presence of oxygen to reduce the degradation and defluorination efficiencies; plus, presence of Fe0 NPs may promote the generation of hydrated electrons. Last, UVC/Fe0 NPs system was used to degrade PFAS from WEs in both bench scale and in a scale up POU system. The degradation efficiencies of PFAS in WEs from both wastewater treatment plants (WWTP) were lower than that in deionized water, likely reflecting the complex compositions in the environmental media. Optimal degradation efficiencies of 90±1%, 88±1%, and 46±2% were obtained for PFNA, PFOS, and PFOA, respectively, each starting from 0.5 μg/L using bare Fe0 at pH 3.0 after 2 h. PFAS removal and bacterial inactivation were achieved simultaneously in the POU system using Fe0 NPs without and with rGO support under UVC irradiation in WEs, although the PFAS levels were still above the regulation levels for discard. These pilot tests provided more data and experiences for the real applications of UVC/Fe0 NP system to PFAS contaminated wastewater or other water matrix treatment.Overall, this research demonstrated a cost-effective and environment-friendly method -- UVC/Fe0 NPs method for PFAS (i.e., PFOA, PFNA, and PFOS) degradation from WEs for water reuse both with and without presence of oxygen. The possible degradation mechanisms of PFAS with different structures were obtained by testing the concentrations of iron ions, intermediate products, and reactive oxygen species (ROS) involved in the reactions. The developed technology can be potentially applied to treat other environmental media (e.g., groundwater, landfill leachate) that are contaminated by PFAS from previous anthropogenic activities.

Download or read book NanoRem Pilot Site Solvay Switzerland written by and published by . This book was released on 2017 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Accelerated Degradation of Chlorinated Solvents by Nanoscale Zero Valent Iron Coated with Iron Monosolfide and Stabilized with Carboxymethyl Cellulose written by Shirin Ghahghaei Nezamabadi and published by . This book was released on 2016 with total page 92 pages. Available in PDF, EPUB and Kindle. Book excerpt: Nanoscale zero-valent iron (nZVI) injections have proven to be a promising approach for the remediation of aquifers contaminated by chlorinated organic pollutants. This study compares the efficacy of nZVI in sulfidated and unamended forms in degrading selected chlorinated hyrocarbons (CHCs). Results show that nZVI amended with iron monosulfide (FeS) increases the rate of dechlorination of CT, CF and 1,1,1-TCA compared to that by unamended nZVI. The focus of this research was to characterize degradation kinetics and degradation byproduct distributions of CT, CF and 1,1,1-TCA by nZVI coated by iron monosulfide, which is represented as nZVI/FeS. To prevent nZVI particles from agglomerating, carboxymethylcellulose (CMC) was used as a stabilizer in all experiments. Results indicated that the nZVI/FeS system was faster and produced less toxic byproducts than nZVI for all CHCs studied. a-elimination in nZVI/FeS system was an important degradation pathway for CF and 1,l,1-TCA: it produces reactive carbene intermediates capable of degrading into benign products such as methane, ethane, and ethene. The effect of sulfide loading on degradation was evaluated with all CHCs studied. Regardless of CHC type, the rate constant (kobs) increased with increasing sulfide loading, reaching the highest amount at 1 wt% sulfide, and then decreased with higher sulfide loading. An additional study focused on the effects of varying of the concentration of nZVI and CMC, and particle longevity on the degradation of 1,1,1-TCA in the nZVI/FeS system with 1 wt.% sulfide. Particle longevity experiments showed that reactivity with 1,1,1-TCA decreases as particles age. nZVI/FeS particles showed a rapid power function decline in reactivity with time. Increasing the amount of iron-reducing chemical during nZVI/FeS synthesis improved reactivity by 43%. The addition of a polyelectrolyte stabilizer at an optimized concentration of 4.0 g/L further increased nZVI/FeS reactivity by 350%. nZVI/FeS shows great potential for treating certain CHCs.

Download or read book Accelerated Degradation of Chlorinated Solvents by Copper modified Nanoscale Zero Valent Iron Cu nZVI Stabilized with Carboxymethyl Cellulose written by Andrew Franze and published by . This book was released on 2015 with total page 89 pages. Available in PDF, EPUB and Kindle. Book excerpt: Nanoscale zero valent iron (nZVI) is a remediation technology that can be used to treat chlorinated hydrocarbons (CHCs) in contaminated aquifers. Nanoparticles remain mobile in water and can be transported with groundwater flow to contaminated zones. However, due to magnetic and van der Waals forces, unstabilized nZVI agglomerates. Carboxymethylcellulose (CMC) was used as a polyelectrolyte stabilizer in this study. nZVI serves as an electron donor and can dechlorinate CHCs. nZVI reactivity with CHCs can be enhanced by addition of a secondary metal catalyst. This study evaluates the potential of copper amended nZVI (Cu-nZVI) to degrade select CHCs. The objective of this study was to characterize degradation of select CHCs in batch reactors with regard to degradation kinetics and degradation byproduct distributions. The following CHCs were studied: CF, 1,1,2,2-TeCA, 1,1,1-TCA, 1,1,2-TCA, PCE, TCE, cis-DCE, trans-DCE, and 1,2,3-TCP. Degradation kinetics were quantified using a pseudo first-order rate constant (kobs). Initial degradation of CHCs was reported separately from later degradation, which occurred after 0.5 hr. The change in reaction kinetics with time could be caused by particle aging. The effect of Cu loading and nZVI concentration was evaluated with CF degradation. Increasing Cu loading or nZVI concentrations yielded faster degradation rates. Increasing Cu loading systematically increased methane byproduct production. The loss of reactivity with CF after 0.5 hr was greater for nZVI when compared to Cu-nZVI. Degradation kinetics were faster and byproduct distribution was more favorable for Cu-nZVI than nZVI for all CHCs studied. Cu-nZVI outperformed most other bimetallic nZVI reductants reported in the literature for CF and chlorinated ethanes treatment. Cu-nZVI invokes a-elimination of CF and 1,l,1-TCA, which produces reactive carbene intermediates capable of degrading into benign products such as methane, ethane, and ethene. Cu-nZVI also showed potential for 1,2,3-TCP remediation. However, Cu-nZVI was particularly ineffective at degrading chlorinated ethenes. Chlorinated ethene degradation pathways and mechanisms induced by Cu-nZVI were not clearly identified. Particle longevity experiments showed that reactivity with 1,1,1-TCA decreases as particles age. Unstable Cu-nZVI particles showed a slow linear decline in reactivity with time, whereas CMC stabilized Cu-nZVI particles showed a rapid power function decline in reactivity with time. The unstable particles were 12-fold faster compared to stablized particles 24 hr after particle synthesis. Even with declines in reactivity, 1,1,1-TCA was rapidly degraded (over a few hours) by both stable and unstable Cu-nZVI seven days after particle synthesis. Cu-nZVI hydrogen production was minor and was limited to occurring immediately after particle synthesis. Cu-nZVI shows great potential for treating certain CHCs.

Download or read book Surface Mediated Reduction of Chlorinated Solvents by Zero valent Iron written by Timothy Lee Johnson and published by . This book was released on 1997 with total page 220 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Nanotechnology for Environmental Remediation written by Sung Hee Joo and published by Springer Science & Business Media. This book was released on 2006-06-18 with total page 170 pages. Available in PDF, EPUB and Kindle. Book excerpt: Examines the suitability of nanoscale zero-valent iron (ZVI) for degradation of agrochemicals. This book identifies by-products produced from the ZVI-mediated degradation process of particular contaminants, and explains the reaction mechanism by which ZVI degrades a chosen contaminant.

Download or read book Development of Reductive oxidative Treatment Strategy for the Removal of Per and Polyfluoroalkyl Substances PFAS in Water written by Akshay Chandrashekar Parenky and published by . This book was released on 2020 with total page 96 pages. Available in PDF, EPUB and Kindle. Book excerpt: The detrimental health effects of halogenated compounds in humans has been well documented, and the frequent occurrence of per- and polyfluoroalkyl substances (PFAS)in the water environment is a recent global concern. Feasible and sensible treatment strategies are in dire need for environmental remediation and water treatment. Currently, efficient treatment is only obtained at a small scale and at a high energy cost. This research is presented in three subsections, where decomposition of selected PFAS was evaluated under advanced oxidation techniques. The first study involved decomposition of a polyfluoroalkyl substance, 6:2 fluorotelomer sulfonate (6:2 FTS), in which 2 carbons of the alkyl chain are hydrogenated making the molecule more vulnerable to degradation. The 6:2 FTS was tested against some of the common oxidants such aspersulfate (PS), peroxymonosulfate and hydrogen peroxide. Interestingly, 6:2 FTS was degraded by PS alone under ambient conditions. Several byproducts and fluoride release were observed and quantified. A decomposition pathway was proposed, and certain reaction intermediates were identified. Upon achieving successful degradation of 6:2 FTS, a highly oxidized perfluorinated compound, perfluoroctanesulfonic acid (PFOS) was investigated. The absence of C-H bonds makes the molecule more resilient to conventional oxidation, hence a synergistic approach of using reduction combined with advanced oxidation was envisioned. This strategy involved the use of electrons generated by zero valent iron as the reductive source in combination with highly reactive radical species such as sulfate radical and hydroxyl radicals as the oxidizing species. This combination of oxidation and reduction was evaluated under several conditions by changing factors such as concentration, pH, and temperature. Significant removal of PFOS was observed in most cases but no transformation was observed. However, when this system was tested for perfluorooctanoic acid (PFOA), decomposition byproducts were observed consisting of short chain compounds demonstrating the potential for this treatment strategy. Although decomposition of PFOA was achieved through the synergistic approach, the constraints of heat requirement reduce the practical applicability of the system. Since oxidants can be activated efficiently by transition metals, several different combinations of metal-oxidants were evaluated. Amongst these combinations, silver-PS was successful in decomposing a variety of carboxylic PFAS under ambient conditions without the use of any external energy source such as heat, ultra-violet or microwave. Significant byproduct and fluoride release were observed upon decomposition of selected PFAS. This system shows great potential for in situ application of PFAS remediation. The reaction mechanism for the system is complex and future studies should: i) investigate the role of silver and identify the reactive species responsible for the reaction, ii) identify an appropriate metal-oxidant pair capable of decomposing sulfonic PFAS, and iii) evaluate the efficacy of these systems for a wider range of PFAS.

Download or read book Chlorinated Solvent and DNAPL Remediation written by Susan M. Henry and published by . This book was released on 2003 with total page 354 pages. Available in PDF, EPUB and Kindle. Book excerpt: Chlorinated Solvent and DNAPL Remediation addresses remediation of chlorinated solvents and dense nonaqueous phase liquids (DNAPLs) in groundwater and discusses remedial alternatives that are available for subsurface cleanup. Chlorinated Solvent and DNAPL Remediation: Innovative Strategies for Subsurface Cleanup focuses primarily on current technological developments and innovative applications for in situ remediation of chlorinated solvents including DNAPLs in soil and groundwater. However, this book also provides a general overview of all of the physical, chemical, and biological processes available for in situ remediation of groundwater contaminated with chlorinated solvents and DNAPLs. Chapters discuss surfactant flushing to enhance DNAPL removal; in situ chemical destruction by reduction processes involving zero valent iron or related metals; in situ chemical destruction by advanced oxidation processes; and in situ biological destruction by enhanced anaerobic bioremediation or natural bioattenuation. This book also emphasizes zero valent iron-based strategies, including reaction geochemistry, permeable reactive barrier longevity, rejuvenation of iron walls, and emplacement technique. One chapter summarizes 10 years of permeable reactive barrier development and application. The controversial issues related to DNAPL remediation, including the concept that remediation of sites affected by DNAPL could be technically impractical, are reviewed. Another chapter focuses on the evolution of DNAPL remediation practice.

Download or read book Chlorinated Pesticide Remediation Using Zero valent Iron Nanoparticles written by Jay Michael Thompson and published by . This book was released on 2008 with total page 116 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Fundamental Studies of the Removal of Contaminants from Ground and Waste Waters Via Reduction by Zero Valent Metals written by and published by . This book was released on 1999 with total page 5 pages. Available in PDF, EPUB and Kindle. Book excerpt: Contaminated groundwater and surface waters are a problem throughout the United States and the world. In many instances, the types of contamination can be directly attributed to man's actions. For instance, the burial of chemical wastes, casual disposal of solvents in unlined pits, and the development of irrigated agriculture have all contributed to groundwater and surface water contamination. The kinds of contaminants include chlorinated solvents and toxic trace elements (including radioisotopes) that are soluble and mobile in soils and aquifers. Oxyanions of uranium, selenium, chromium, arsenic, technetium, and chlorine (as perchlorate) are frequently found as contaminants on many DOE sites. Uranium is a particularly widespread contaminant at most DOE sites including Oak Ridge, Rocky Flats, Hanford, Idaho (INEEL), and Fernald. The uranium contamination is associated with mining and milling of uranium ore (UMTRA sites), isotope separation and enrichment, and mixed waste and TRU waste burial. In addition, the careless disposal of halogenated solvents, such as carbon tetrachloride and trichloroethylene, has further contaminated many groundwaters at these sites. A potential remediation method for many of these oxyanions and chlorinated-solvents is to react the contaminated water with zero-valent iron. In this reaction, the iron serves as both an electron source and as a catalyst. Elemental iron is already being used on an experimental basis at many DOE sites. Both in situ reactive barriers and above-ground reactors are being developed for this purpose. However, the design and operation of these treatment systems requires a detailed process-level understanding of the interactions between the contaminants and the iron surfaces. We are performing fundamental investigations of the interactions of the relevant chlorinated solvents and trace element-containing compounds with single- and poly-crystalline Fe surfaces. The aim of this work is to develop th e fundamental physical and chemical understanding that is necessary for the development of cleanup techniques and procedures.

Download or read book Removal of Select Chlorinated Hydrocarbons by Nanoscale Zero valent Iron Supported on Powdered Activated Charcoal written by Md Abu Raihan Chowdhury and published by . This book was released on 2017 with total page 64 pages. Available in PDF, EPUB and Kindle. Book excerpt: Nanoscale Zero Valent Iron (NZVI) has shown limited effectiveness in degrading chlorinated hydrocarbons (CHCs), like 1,1,1-Trichloroethane (1,1,1-TCA) and Trichloroethene (TCE), in aqueous solution. A rapid agglomeration behavior of NZVI particles due to van der waals and magnetic forces can negatively impact its overall effectiveness due to increase in particle size, and decline in CHC degradation kinetics. Different support materials, such as clays and activated carbon, have been used to stabilize NZVI particle and reduce agglomeration in aqueous solution. In this bench-scale study, NZVI supported on Powdered Activated Charcoal (PAC) was selected to prepare a composite, called PAC/NZVI, for a more effective treatment of 1,1,1-TCA and TCE in aqueous solution. The study shows that PAC/NZVI has both adsorption and degradation capability toward 1,1,1-TCA and TCE. PAC exhibited high porosity to accommodate NZVI as a suitable support in order to keep NZVI in suspension in aqueous medium and to minimize agglomeration. Bench-scale experiments with variable concentrations of PAC (0.1{u2013}0.8 g/L) and NZVI (0.2{u2013}0.6 g/L) showed that PAC/NZVI composite can be highly efficient in rapid 1,1,1-TCA removal by adsorption, and effective in overall degradation leading to production of non-chlorinated daughter products. Increase in PAC concentration in the composite was correlated with greater removal of 1,1,1-TCA by sorption whereas lower PAC concentration yielded greater degradation kinetics and higher byproduct yields. PAC/NZVI was found to be active for more than three months presumably because NZVI embedded within hydrophobic pore spaces of PAC did not get oxidized. Cu amendment to NZVI as a secondary/catalysts metal showed faster degradation and higher byproduct yields.

Download or read book NanoRem Pilot Site Nitrastur Spain written by and published by . This book was released on 2017 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Evaluation of the Removal of Perfluoroalkyl Substances from Aqueous Matrices in the Presence of Zerovalent Iron written by Janis Rachel Baldwin and published by . This book was released on 2018 with total page 109 pages. Available in PDF, EPUB and Kindle. Book excerpt: Per- and polyfluoroalkyl substances (PFASs) are a class of persistent organic pollutants present in the environment that pose a threat to human health. PFASs primarily reside within aqueous phases and are present in groundwater environments. Perfluorooctane sulfonic acid (PFOS) and perfluorooctanoic acid (PFOA) are the most predominant PFASs. Remediation techniques focus on oxidation and sorption methods, both of which lack efficacy for all PFASs. There are few studies on reduction treatments such as zerovalent iron (ZVI), which demonstrate potential for both PFOS and PFOA removal and can be applied in subsurface environments. This thesis describes laboratory batch experiments that evaluate PFOS and PFOA removal in the presence of ZVI under a range of physical and geochemical conditions. Mechanisms of removal are explored utilizing PFAS mass balances based on a series of analyses that include aqueous phase fluoride and PFAS short chains, and PFAS extractions from the iron surface. Solid iron phase characterization provides supporting information regarding PFAS interaction with the iron surface. Laboratory batch experiments with PFOS in the presence of granular ZVI were conducted under combinations of initial pH (pH 2.0 and 6.6), temperature (~22°C and 60°C) and ZVI dosage (179 and 1792 mM). PFOS removal was enhanced under low initial pH likely due to a greater abundance of iron oxides compared to higher pH conditions. Higher temperatures also enhanced PFOS removal. PFOS removal by sorption generally increased under low pH and high ZVI dosed conditions, suggesting the abundance of iron oxides and surface area may play an important role. Laboratory batch experiments of PFOS and PFOA in the presence of zerovalent iron nanoparticles (nZVI) were conducted under combinations of initial pH (pH 2.0 and 8.3) and coating (uncoated and palladium-coated). The iron phase likely changed over time, as there was some release of PFOS and PFOA into aqueous solution compared to earlier sampling times. The presence of a palladium coating appeared to minimize the effects of iron corrosion, as PFOS and PFOA were released to a lesser degree at later time points compared to uncoated nZVI. PFOS and PFOA removal is likely dominated by electrostatic interaction, however functional group interaction with the iron surface may also play an important role.

Download or read book Field Scale Application of Nanoscale Zero Valent Iron written by Michael Donald Kocur and published by . This book was released on 2015 with total page 546 pages. Available in PDF, EPUB and Kindle. Book excerpt: This thesis began by verifying that nanoscale zero valent iron (nZVI) synthesis methods could be scaled up and implemented at the field scale in a safe manner. This led to successful demonstration of nZVI injection and mobility under constant head gravity injection into a contaminated utility corridor in Sarnia, Ontario. Where field studies have fallen short in the past was linking the somewhat qualitative field geochemical parameters to other evidence of nZVI transport. Definitive nZVI detection was elusive in previous field studies due to the highly reactive nature of the particles caused by their high surface area. nZVI was detected and characterized in this study using UV/Vis spectrophotometry, Dynamic light scattering, zeta potential, Transmission Electron Microscopy, and energy dispersive x-ray spectroscopy, proving that field mobility was reliably achieved. The second study provides the first insight into the interactions and reaction that occur on an active field site immediately following nZVI injection. A fine temporal resolution of samples was used to define chlorinated ethene, ethane, and methane (cVOC) degradation among nZVI impacted zones, showing that these zones were distinct from areas that were not affected by nZVI. Building upon previous indirect evidence that nZVI enhances organohalide-respiring microorganisms, this study set out to prove that microbiological communities on sites were enhanced following injection. Quantitative polymerase chain reaction (qPCR) was used to target Dehalococcoides spp. (dhc) and vinyl chloride reductase genes (vcrA). The distinct zones where nZVI treatment was applied subsequently had high abundances of dhc and vcrA. The qPCR methods presented in the second study can act as a template for future field investigation on nZVI. Finally, the long-term effects of the injection amendments nZVI and Carboxymethyl-cellulose were monitoring on the microbial communities on site. It was hypothesized that the organohalide-respiring species on site would be enriched and cVOC degradation would be sustained due to the polymer amendments that accompany nZVI injection. Over a two year period next-generation pyrosequencing, qPCR, and cVOC degradation were monitored, providing the first ever phylum level microbiological evaluation at a field site undergoing remediation.

Download or read book Final Laboratory Treatabilty Report For Emulsified Zero Valent Iron Treatment of Chlorinated Solvent DNAPL Source Areas Revision 1 0 written by and published by . This book was released on 2006 with total page 81 pages. Available in PDF, EPUB and Kindle. Book excerpt: This Laboratory Treatability Report has been prepared by GeoSyntec Consultants, Inc. (GeoSyntec) for the Environmental Security Technology Certification Program (ESTCP) review committee to present the results of the Pre-Design Laboratory Testing conducted as part of ESTCP project CU-043 1. Laboratory experiments were conducted by SiREM Laboratories (a division of GeoSyntec) to determine the extent of DNAPL mass destraction by enlisted zero-valent iron (EZVI) that is due to abiotic and biological processes. GeoSyntec will review the results presented in this report with ESTCP and make a Go$No- Go decision regarding additional project tasks.

Download or read book Electrochemical Remediation of Radionuclide and Trichloroethene contaminated Groundwater Using Zero valent Iron iron Oxides and Mineralogical Characterization of Iron Hydroxides Formed from Zero valent Iron written by Yul Roh and published by . This book was released on 1998 with total page 346 pages. Available in PDF, EPUB and Kindle. Book excerpt: