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Different substituted 2‐chloromethylpyridyl derivatives (6a–d) were oxidized with mCPBA to give the respective 2‐chloromethylpyridine‐N‐oxide derivatives (7a–d) at low temperature, which on condensation with 2‐mercapto‐1H‐benzimidazole (8a–c) in the presence of aprotic solvents give the 2‐[[(pyridin‐2‐yl‐1‐oxide)methyl]sulfanyl]‐1H‐benzimidazole (9a–d) in good yield. Finally, 9a–d oxidized with mCPBA in chlorinated solvent gives a mixture of 2‐[[(pyridin‐2‐yl‐1‐oxide)methyl]sulfonyl]‐1H‐benzimidazole (3a–d, 10%) and 2‐[[(pyridin‐2‐yl‐1‐oxide) methyl]sulfinyl]‐1H‐benzimidazole (4a–d, 90%) derivatives.

The long-term growth process of two microbial consortia effective in the aerobic cometabolic biodegradation of a mixture of 6-chlorinated aliphatic hydrocarbons (CAHs), the effectiveness of these consortia as inocula for the bio-augmentation of different types of microcosms and the development of a double-substrate, high-performing consortium is presented. The propane-utilizing consortium generally proved to be the most effective one, being able to biodegrade vinyl chloride, cis- and trans-1,2-dichloroethylene, trichloroethylene, 1,1,2-trichloroethane and 1,1,2,2-tetrachloroethane at all the CAH concentrations tested (4 μM). Both consortia maintained unaltered CAH degradation capacities over a 300-day growth period in the absence of the CAHs and were effective in inducing the rapid onset of CAH depletion upon inoculation in slurry microcosms set up with five types of aquifer materials. A consortium supplied with both methane and propane combined the best degradation capacities of the two single-substrate consortia, and maintained stable performances for 150 days under slurry conditions. The degree of conversion of the organic Cl to chloride ions was equal to 90 %.

Dendroecology, or the use of ring patterns to assess the age of trees and environmental factors controlling their growth, is a well-developed method in climatologic studies. This method holds great potential as a forensic tool for age dating, contamination assessment, and characterization of releases. Moreover, the method is independent of the physical presence of contamination at the time of sampling because it is focused on the effect rather than the cause. This review is one of the very few articles published to date exploring the forensic applicability of dendroecology. This article is organized in two parts: Part I describes the method principles and proposes a practical procedure for forensic applications; Part II exemplifies and validates the method through six case studies of successful forensic application (related to petroleum products and chlorinated solvent spills).

The synthesis and spectroscopic characterization of the new hydroxo-bridged platinum(II) complex [P(μ-OH)(Pom-Pom)] 2 [BF 4 ] 2 ( 3 ) containing the electron-poor P–P ligand 1,2-bis(dimethoxyphosphino)ethane, (OMe) 2 PCH 2 CH 2 P(OMe) 2 (Pom-Pom), is reported. This compound has been used in the Baeyer–Villiger oxidation of a series of cyclic ketones using 35% hydrogen peroxide as oxidant. The reactions were performed at 25 °C and at 70 °C in chlorinated solvent/H 2 O biphasic system. The catalytic activity and the Lewis acidity of the complex ( 3 ) has been compared to other Pt(II) complexes previously investigated.

An Accelerated Remediation Technologies (ART) In-Well Technology pilot test was performed to evaluate the removal of chlorinated volatile organic compounds (VOCs) from groundwater. The ART In-Well Technology was installed in one well located in the source area where dense nonaqueous-phase liquid has been identified and VOC concentrations exceed 140,000 μg/L. Monitoring wells at the site were positioned between 10 and 170 feet from the ART test well. Overall, VOC concentrations from samples collected from the groundwater monitoring wells and in the vapors extracted for discharge from the ART treatment well were analyzed over the testing period. Monitoring results showed that concentrations of perchloroethylene were reduced in the closest monitoring well to nondetectable concentrations within 90 days. The cumulative removal of chlorinated VOCs from the ART test well over the six-month pilot test period exceeded 9,500 pounds based on air monitoring data. The ART technology proved effective and cost-efficient in reducing contaminant concentrations and removing a large mass of contamination from the subsurface in a short period of time. The radius of influence of the ART technology at the site was estimated to range between 65 and 170 feet. © 2007 Wiley Periodicals, Inc.

Introduction: Trichloroethylene (TCE) is a chlorinated solvent used extensively in industries. It has been linked to numerous biological possible health effects. However, workers exposed to TCE pre...

Dihaloalkynes of the type YCH(R)C CCH(R)Y (Y = Cl, Br, I; R = H or Me) or YCMe 2 C CCMe 2 Y were prepared from their diol precursors and reacted with [Mo(CO) 3 (phen)Y] − (phen = 1,10-phenanthroline) in chlorinated solvent, methanol or water. Formation and stability of substituted products of the type [Mo(CO) 2 (η 3 -CH(R)C(COX)C CH(R))(phen)Y] (X = Y or X = OMe) were found to be dependent upon the nature of the halogen and degree of alkyl substitution of the alkyne. Reactions carried out in mixtures of methanol and ethers gave an alternative double addition product of the type [Mo(CO) 2 (η 3 -CH(R)C(CO 2 Me)C C(OMe)(CH 2 R))(phen)Y] for R = H, Y = Cl only.

Based on toxicology, metabolism, animal studies, and human studies, occupational exposure to chlorinated aliphatic solvents (methanes, ethanes, and ethenes) has been associated with numerous adverse health effects, including central nervous system, reproductive, liver, and kidney toxicity, and carcinogenicity. However, many of these solvents remain in active, large-volume use. This article reviews the recent occupational epidemiology literature on the most widely used solvents, methylene chloride, chloroform, trichloroethylene, and tetrachloroethylene, and discusses other chlorinated aliphatics. The impact of studies to date has been lessened because of small study size, inability to control for confounding factors, particularly smoking and mixed occupational exposures, and the lack of evidence for a solid pathway from occupational exposure to biological evidence of exposure, to precursors of health effects, and to health effects. International differences in exposure limits may provide a "natural experiment" in the coming years if countries that have lowered exposure limits subsequently experience decreased adverse health effects among exposed workers. Such decreases could provide some evidence that higher levels of adverse health effects were associated with higher levels of solvent exposure. The definitive studies, which should be prospective biomarker studies incorporating body burden of solvents as well as markers of effect, remain to be done.

Long-term e.g., 5-15 years groundwater concentration versus time records were compiled from 47 near-source zone moni- toring wells at 23 chlorinated solvent sites 52 total records. Chlorinated volatile organic compound CVOC concentrations decreased significantly in most of the 52 temporal records, with a median reduction in concentration of 74%. A statistical method based on a Mann-Kendall analysis also showed that most sites had statistically significant decreasing concentration trends over time. Median point decay rate constants kpoint values were calculated for nine sites containing tetrachloroethene PCE; 13 sites containing trichloroethene TCE; two sites containing cis-1,2-dichloroethene DCE; and six sites containing 1,1,1-trichloroethane TCA. The TCA sites had the highest kpoint values 0.34/year followed by PCE, DCE, and TCE 0.23/year, 0.16/year, and 0.11/year, respectivelyequal to decay half-lives of 2.0, 3.0, 4.3, and 6.1 years, respectively. If the median point decay rates from these sites are maintained over a 20 year period, the resulting reduction in concentration will be similar to the reported reduction in source zone concentrations achieved by active in situ source remediation technologies typical project length: 1-2 years.

The preparation and characterization of second-generation electron-poor Pt(II) complexes of general formula [(P−P)Pt(C6F5)(H2O)][X], 1a−h (P−P = diphosphine, X = BF4, OTf), bearing a pentafluorophenyl ligand is reported. The complexes are investigated as catalysts in the epoxidation of alkenes with hydrogen peroxide in a chlorinated solvent/H2O two-phase system. The effects of the P−P ligands and of the Lewis acidity of the metal species are discussed with respect to the catalytic activity in the epoxidation reaction.

Performance and rebound of intensive source depletion technologies were evaluated at 59 chlorinated solvent sites where remediation targeted dense non–aqueous phase liquid (DNAPL) source zones. The four technologies included in the study are chemical oxidation, enhanced bioremediation, thermal treatment, and surfactant/cosolvent flushing. Performance was evaluated by examining temporal ground water concentration data before and after source remediation was performed. Results indicated that all four technologies have median concentration reductions of 88% or greater for the parent chlorinated volatile organic compound (CVOC). Approximately 75% of the source depletion projects were able to achieve a 70% reduction in parent compound concentrations. A median reduction in total CVOC concentrations (parent plus daughter compounds) of 72% was observed at 12 chemical oxidation sites and 62% at 21 enhanced bioremediation sites. Rebound was assessed at sites having at least 1 year of posttreatment data. Rebound occurrence was most prevalent at sites implementing chemical oxidation. At chemical oxidation sites where rebound was evaluated (n ¼ 7), the median parent CVOC concentration reduction was 90% immediately following treatment compared to 78% at the end of posttreatment monitoring (i.e., 1 to 5 years after treatment). For enhanced bioremediation sites where rebound was evaluated (n ¼ 10), median parent CVOC concentration reduction changed from 77% to 96% over the posttreatment monitoring period. Minimal concentration change was observed over the posttreatment monitoring period at surfactant/cosolvent sites (n ¼ 2) and thermal treatment sites (n ¼ 1) evaluated for rebound. Based on current data, none of the 59 source depletion projects was able to meet maximum contaminant levels throughout the treatment zone for all CVOCs.

Monitored natural attenuation (MNA), while a remedy of choice for many sites, can be challenging when the contaminants are chlorinated solvents. Even with many high-quality technical guidance references available, there continue to be challenges implementing MNA at some chlorinated solvent sites. The U.S. Department of Energy, as one organization facing such challenges, is leading a project that will incorporate developing concepts and tools into the existing toolbox for selecting and implementing MNA as a remediation option at sites with chlorinated solvent contamination. The structure and goals of this project were introduced in an article in the Winter 2004 issue of Remediation (Sink et al., 2004). This article is a summary of the three technical areas being developed through the project: mass balance, enhanced attenuation, and characterization and monitoring supporting the first two areas. These topics will be documented in separate reports available from the U.S. Department of Energy Office of Scientific and Technical Information at www.osti.gov. © 2006 Wiley Periodicals, Inc.

The value of using an abstraction well-based monitoring approach to diagnose an aquifer9s chlorinated solvent condition is successfully demonstrated for the urbanized Birmingham aquifer, UK. Data from surveys conducted a decade apart (1986–89 and 1998–2001) were compared. Trichloroethylene (TCE) was the principal solvent detected at 78% of abstraction sites in 1987. This reduced to 56% of sites by 1998. The decline in percent occurrence is attributed to closure of abstractions associated with former solvent-user industries rather than signifying an improvement in aquifer quality. Indeed, comparison of abstractions common to both surveys indicated greater contamination in the more recent survey that was attributed to the persistency of historical dense nonaqueous-phase liquid (DNAPL) source zones. Persistence of perchloroethylene (PCE) relative to TCE was observed and ascribed to its lower solubility and greater sorption. Biodegradation was evident, but insufficient to prevent parent solvents from being detected at half of the non-solvent user sites sampled in 1998. Nevertheless solvent-free water can still be abstracted. This may, however, become increasingly difficult as industrial recession has caused closure of many solvent-user industry abstractions previously thought to have been undertaking inadvertent pump-and-treat of plumes. Such plumes are now able to more freely migrate throughout the aquifer. The observed persistency of solvent contamination spanning a decade suggests that the European Water Framework Directive (WFD) requirement to obtain good chemical status is unlikely to be achieved within the required timescales for solvent-contaminated urban aquifers.

Nine extraction methods (three using chlorinated and six nonchlorinated solvents) were compared for determining lipids in samples of low-( 20%) ground beef. The nine methods investigated were: Folch, Lees, and Sloane Stanley (FLS); Bligh and Dyer (BD); Bligh and Dyer modified by Undeland, Harrod, and Lingnert (BDU); Bligh and Dyer modified by Smedes (BDS); Hara and Radin (HR); Schmid, Bondzynski, and Ratzalaff (SBR); Roese-Gottlieb (RG); Burton, Webb, and Ingold (BWI); and Soxhlet (SE). The BDS and HR methods do not include solvents such as chloroform and methanol and can be recommended for meat samples that have both low and high fat content. If the use of organic solvents is not critical, the FLS and the BD extraction methods yield the highest results, but the FLS is more expensive owing to the high amount of solvent required. Without considering the toxicity of the solvents, the three BD extraction methods provided the best yields.

To further our understanding of the groundwater-to-indoor-air exposure pathway, a database of 270 paired groundwater and indoor air measurements of volatile organic compounds (VOCs) from 31 sites has been compiled and analyzed. Using regression analyses, these data have been analyzed to (1) detect evidence of indoor air impacts from dissolved petroleum hydrocarbons or chlorinated solvents in underlying groundwater, (2) estimate the true attenuation factor for volatilization from groundwater to indoor air, and (3) assess the utility of popular groundwater-to-indoor-air transport models for evaluating this exposure pathway. Key findings include the following: (1) > 95% of the indoor air concentrations fall within or below the range of national background indoor air values; (2) there is no correlation between petroleum constituent concentrations measured in groundwater and the concentrations of these VOCs in indoor air of overlying structures; and (3) for chlorinated solvent cases, a correlation between grou...

A survey of experts in the application of natural attenuation was conducted to better understand how monitored natural attenuation (MNA) is being applied at chlorinated solvent sites. Thirty-four remediation professionals provided general information for 191 sites where MNA was evaluated, and site-specific data for 45 chlorinated solvent plumes being remediated by MNA. Respondents indicated that MNA was precluded as a remedy at only 23 percent of all sites where evaluated as a remedial option. Leading factors excluding MNA as a remedial approach were the presence of an expanding plume and an unreasonably long estimated remediation time frame. MNA is being used as the sole remedy at about 30 percent of the sites, and 33 percent are implementing MNA in conjunction with source zone remediation. The remaining sites are implementing MNA with plume remediation (13 percent), source containment (9 percent), or some other strategy (16 percent). © 2004 Wiley Periodicals, Inc.

To select and design effective remedial measures for dense, nonaqueous phase liquid (DNAPL) source zones, better understanding of the architecture of these zones is needed. In this study, a suite of investigative techniques was applied to perform detailed vertical delineation of chlorinated-solvent source zones in sand aquifers at five contaminated industrial sites (two in Connecticut, and one each in Florida, New Hampshire, and Ontario). The DNAPL occurs in the middle of the aquifers at three of the sites and at or near the bottom at the other two. The DNAPL entered the subsurface at these sites decades ago, and therefore the DNAPL zones have aged due to groundwater dissolution. The suite of investigative techniques was used to perform profile sampling using direct-push methods, in which depth-discrete soil and groundwater samples were taken with extremely close vertical spacing. The sampling included methods to distinguish between free-product and residual DNAPL at two of the sites. At each location where DNAPL was found, the DNAPL occurred in one or a few thin layers, generally between 1 and 30 cm thick. These layers were positioned within distinct grain-size zones, or at contacts between sedimentological layers. In some cases, the DNAPL layers have no apparent textural association. For any particular sampling hole to have a high probability of finding such layers, continuous cores must be collected and sampling of these cores must be done at very close vertical spacing (5 cm or less). Free-product DNAPL occurrences in conventional wells at three of the sites indicated, misleadingly, much greater DNAPL layer thicknesses than actual, and in one case, the conventional well may have caused short-circuiting of DNAPL from the middle to the bottom of the aquifer. Although all of the DNAPL source zones are comprised of only sporadic, thin DNAPL layers representing little total mass, these source zones are the cause of high-concentration dissolved plumes down gradient.

This is a study of carcinogen risk assessment of the chlorinated solvent trichloroethylene within the European Union existing substances program and the classification and labeling process. The focus is on the most active and influential participants of this process, namely, those from the United Kingdom, Germany, and Sweden, and from industry. The member state and other experts have different opinions regarding the appropriate classification of trichloroethylene for mutagenicity (no classification or category 3) and carcinogenicity (category 3, 2, or 1). In this article these differences are described, as well as how the primary carcinogenicity and mutagenicity data have been interpreted and evaluated by these participants. It is concluded that underlying the different assessments are disagreements about issues that to some degree lie outside the scope of purely scientific considerations.

Chlorinated solvents, especially tetrachloroethene (perchloroethylene or PCE), trichloroethylene (TCE), and methyl chloroform (1,1,1-trichloroethane or TCA) are among the most widespread volatile organic compounds (VOCs) detected in soil and groundwater. Given their frequency of detection in environmental investigations, techniques to age date and identify the origin of chlorinated solvent releases are of great interest in environmental forensic investigations. Since the 2007 publication of the second edition of Introduction to Environmental Forensics, additional forensic techniques and/or refinements of existing methods specific to chlorinated solvents have arisen, including diagnostic stabilizers, manufacturing impurities, compound-specific isotope analysis (CSIA), and reconstructed plume techniques, which are the focus of this chapter.

Bacterial dechlorination of chlorinated solvents often causes accumulation of the intermediate cis-DCE. Back diffusion of e.g. cis-DCE, due to the dual porosity of limestone, often limits the remediation efficiency. A remediation scheme capable of establishing contact between contaminant, degrading bacteria and electron donor within the low permeable limestone matrix is required. The technology EK-BIO, which combines enhanced reductive dechlorination and electrokinetics (EK), was assessed. This novel technology has not previously been tested in limestone. An experimental set-up was designed to meet the requirements of anaerobic bacteria and to manage the volatile contaminants and extreme pH development prompted by electrolysis. The experimental set-up was tested and recommendations for design improvements presented. In this study, supplementary methods were developed for e.g. sampling of intact bryozoan limestone cores and for saturation and contamination of the cores with cis-DCE. EK induced transport processes for delivery of the donor lactate and mixed bacteria culture KB-1 ® were studied. EK was shown to enhance delivery of lactate and bacteria resulting in fermentation of lactate in the limestone. Lactate was delivered by electromigration causing an increase in electric conductivity. No indications of establishment of electro-osmotic flow in limestone were observed. Presence of specific cis-DCE degraders, Dehalococcoides , in the limestone could not be verified. However, the results indicated that fermentative bacteria were distributed by electrophoresis. This study suggests that EK application can establish the essential contact and overcome back diffusion. Thereby, EK-BIO may be superior to advection-based technologies for bioremediation of chlorinated solvent contaminated limestone matrices.

Reactivity and stability of trifluoromethylcyclohexane (TFMC) has been investigated towards various reagents, in order to evaluate its possible use as solvent. TFMC is stable in most oxidizing conditions, indicating the protective effect of a fluoroalkyl substituent towards oxidation, and surprisingly, it is also very stable towards strong bases. TFMC has also been assessed as a chlorinated solvent substitute in some reactions. It is clearly adapted as a CCl 4 substitute in allylic bromination reaction.

Objectives This study investigated the associations between occupational exposures to solvents and metals and fixed airflow obstruction (AO) using post-bronchodilator spirometry. Methods We included 1335 participants from the 2002-2008 follow-up of the Tasmanian Longitudinal Health Study. Ever-exposure and cumulative exposure-unit (EU) years were calculated using the ALOHA plus job exposure matrix (JEM). Fixed AO was defined as post-bronchodilator forced expiratory volume in one second (FEV1)/forced vital capacity (FVC)

Older maternal age has been observed to modify associations between maternal residential proximity to industrial air emissions of solvents and birth defects in offspring. However, the number of old...

The site characterization and analysis cone penetrometer system (SCAPS), equipped with realtime fluorophore detection capabilities, was used to delineate subsurface contaminant releases in an area where plating shop waste was temporarily stored. Records indicated that various nonaqueous phase liquids (NAPLs) were released at the site. The investigators advanced the SCAPS laser-induced fluorescence (LIF) sensor to depths beneath the water table of the principal water-bearing zone. The water table was located approximately 6 feet (1.8 m) below ground surface (bgs) across the site. Fluorescence, attributed to fuel compounds commingled with chlorinated solvents, was observed at depths ranging from 4.0 to 11.5 feet (1.2 to 3.5 m) bgs. Fluorescence, attributed to naturally occurring organic materials (by process of elimination and spectral characteristics) commingled with chlorinated solvent constituents, was observed at depths ranging from approximately 13 to 40 feet (4.0 to 12.2 m) bgs. Fluorescence responses from compounds confirmed to be commingled with chlorinated solvents indicates that the SCAPS fluorophore detection system is capable of indirectly delineating vadose zone and subaqueous chlorinated solvents and other dense nonaqueous phase liquids (DNAPLs) at contaminant release sites. This confirmation effort represents the first documented account of the successful application of LIF to identify a mixed DNAPL/LNAPL source zone.

The objectives of this paper are to review the wide range of kinetic models that have been introduced to describe the cometabolic oxidation of chlorinated solvents, to compare modeling approaches and associated experimental data, and to discuss knowledge gaps in the general topic of cometabolism kinetics. To begin, a brief description of the mechanism of oxygenase enzyme metabolism and its qualitative effects on cometabolic degradation kinetics is given. Next, a variety of kinetic expressions that have been used to describe cometabolism, ranging from adaptations of simple metabolic relationships to the development of complex equations that account for intracellular concentrations of key reaction species, are presented. A large number of kinetic coefficients published for a variety of oxygenase populations degrading a broad range of chlorinated solvents are categorized and compared. The discussion section of the paper contains an exploration of knowledge gaps that exist in our understanding of the kinetics of aerobic chlorinated solvent cometabolism. Specific topics covered include: • the use of half saturation constants (Ksc and Ksg) as estimates for inhibition constants (Kisc and Kisg) in saturation modeling expressions, • the specific nature of chlorinated solvent induced product toxicity and the capability for cells to recover from toxic effects, and • methods for incorporating reducing energy limitations into cometabolism models. Finally, the applicability of the broad range of kinetic modeling approaches to scale-up and field applications for in situ bioremediation of chlorinated solvents is discussed.

The reaction of [Ru2(CO)4(μ-CO)(μ-dppm)2] (1) with alkynes RCCR′ gives the alkyne complexes [Ru2(CO)4(μ-RCCR′)(μ-dppm)2] [2, R′=H; 3, R′=CO2Me or COMe; 4, R′=CCR], [Ru2(CO)4H(CCR)(μ-dppm)2] (5) or [Ru2(CO)2(μ-CO)H(μ-CCR)(μ-dppm)2] (6), when R=Ph. Complex 6 reacts with chlorinated solvent to give [Ru2(CO)2(μ-CO)Cl(μ-CCR)(μ-dppm)2] (7), R=Ph. Complex 1 reacts with excess alkyne RCCH to give [Ru2(CO)2(μ-CO){C(CH2)R}(μ-CCR)(μ-dppm)2] (8), when R=Ph, Bu or CH2CH2CCH, and, when R=Ph, 8 reacts with more PhCCH to give [Ru2(CO)2(μ-CCHPh){C(CH2)Ph}(μ-CCPh)(μ-dppm)2] (9), a complex containing three different organic ligands (alkenyl, alkynyl and vinylidene).

Degreasing is an essential part of the modern production process, particularly in industries fabricating or assembling metal parts including aircraft, appliance, automotive. electronics, and railroad manufacturers. The process is widely used to remove oils and oil-borne soils, such as chips, metal fines, and fluxes, from objects that have been stamped, machined, welded, soldered, molded, or die-cast. Parts ranging from tiny printed-circuit assemblies to diesel motors can all be safely, completely, and quickly cleaned with modern vapor degreasing techniques, in most cases more effectively than with aqueous or semiaqueous processes, particularly when a high level of cleanliness is required. Vapor degreasing is ideal for reaching into small crevices in parts with convoluted shapes to remove stubborn soils. Parts degreased in chlorinated solvent vapors come out of the process dry; there is no need for an additional drying stage, as in aqueous and semiaqueous processes.

The reaction of [Pt(dppm)2]Cl2, dppm = Ph2PCH2PPh2, with [HRu(CO)4]- in a 1:2 ratio leads in a multistep reaction to the new heteronuclear cluster [PtRu2(CO)5(μ-CO)(μ-dppm)2], which contains a triangle of metal atoms having both Pt−Ru edges bridged by dppm ligands. The initial step in the reaction is the formation of the heterobimetallic complex [PtRuH(CO)3(μ-dppm)2]+, which then reacts with additional [HRu(CO)4]- to form the PtRu2 cluster. In the absence of excess [HRu(CO)4]-, the complex [PtRuH(CO)3(μ-dppm)2]+ undergoes chloride for carbonyl substitution at ruthenium to give [PtRuHCl(CO)(μ-CO)(μ-dppm)2]. This complex then reacts further with chlorinated solvent to give [PtRu(Cl)2(CO)2(μ-dppm)2], which exists in two isomeric forms, one of which contains a semibridging carbonyl ligand. The structures of [PtRu2(CO)5(μ-CO)(μ-dppm)2] and one isomer of [PtRu(Cl)2(CO)2(μ-dppm)2] have been determined crystallographically.

The transfer of laboratory scale solution processing of organic electronics to large area roll-to-roll production requires the use of up-scalable deposition techniques. Furthermore, industrial production demands the omission of halogenated and other harmful solvents. Here, the authors discuss large area inkjet printing using industrial printheads for organic light emitting diodes (OLEDs) or organic photovoltaics (OPVs) applying halogen-free ink formulations. For the inkjet printing of the small molecule OLED emissive layer a low viscosity ink was selected (1.5 mPa s) to obtain layers with outstanding thickness homogeneity. Devices with 3.75 cm2 active area showed a uniform light emission similar to a device with a spin-coated emissive layer. Ink selection for the photo-active layer for OPVs was mostly determined by the device performance and the solubility of the polymer:electron acceptor blend. The inkjet printed layer showed a significant coffee stain effect, which was dependent on the printed layer thickness as well as the printed area. The loss of active material became smaller for larger printed areas. Devices with the inkjet printed photo-active layer from the halogen-free ink showed similar performance to a layer spin-coated from chlorinated solvents. This shows the potential of inkjet printing as a development and production tool for a variety of large area organic electronics.

Combining in situ heating with physical recovery, chemical reaction and biodegradation processes has led to a spectrum of in situ thermal remediation options for the cleanup of soils, rock and groundwater impacted by dense nonaqueous phase liquids. The growth in the application and understanding of these technologies over the past two decades has been significant – to the point that their potential application is considered for many sites having short target cleanup time frames (less than a few years) and for contaminants that are not accessible by other cleanup technologies (such as mass diffused into fine-grained media). This chapter presents an overview of the most practiced thermal remediation technologies. The chapter then provides a synthesis of the available data from several field applications, summarizes the lessons learned to date and finally summarizes the current understanding of their performance presents several case studies. of well-monitored field-scale applications.

Chlorinated solvents are widespread groundwater contaminants whose physical and chemical properties make them difficult to locate and treat within the subsurface. In particular, remediating chlorinated solvent source zones has proven technically challenging, costly and contentious. Nevertheless, there has been a concerted effort over the past 20-25 years to remediate these source zones, involving development of several in situ technologies. This chapter summarizes the knowledge gained from these efforts, and serves as an introduction to the entire volume. The chapter first summarizes the evolution of the conceptual model of DNAPL source zones, and then describes the current model of a 5-stage life cycle, with a long final stage of back diffusion and desorption. The chapter then summarizes the development of the important remediation technologies, followed by an overview of the current state of the practice. The chapter includes brief summaries of the remaining chapters, and concludes with a summary of the current needs, both for research and for the highly-qualified personnel required to manage groundwater restoration in the future.

In the past decade, the advent of innovative diagnostic tools has improved site assessment and remediation practices. This chapter discusses five diagnostic tools that are particularly important for chlorinated solvent source zone remediation: multi-level monitoring systems; rock matrix characterization techniques; mass flux/mass discharge measurements; compound-specific isotope analysis; and molecular biological tools. The discussion includes descriptions of each diagnostic tool, a value of information analysis to help practitioners determine when the tools will be useful and cost effective, and practical recommendations for use of each tool.

The transfer of laboratory scale solution processing of organic electronics to large area roll-to-roll production requires the use of up-scalable deposition techniques. Furthermore, industrial production demands the omission of halogenated and other harmful solvents. Here, the authors discuss large area inkjet printing using industrial printheads for organic light emitting diodes (OLEDs) or organic photovoltaics (OPVs) applying halogen-free ink formulations. For the inkjet printing of the small molecule OLED emissive layer a low viscosity ink was selected (1.5 mPa s) to obtain layers with outstanding thickness homogeneity. Devices with 3.75 cm2 active area showed a uniform light emission similar to a device with a spin-coated emissive layer. Ink selection for the photo-active layer for OPVs was mostly determined by the device performance and the solubility of the polymer:electron acceptor blend. The inkjet printed layer showed a significant coffee stain effect, which was dependent on the printed layer thickness as well as the printed area. The loss of active material became smaller for larger printed areas. Devices with the inkjet printed photo-active layer from the halogen-free ink showed similar performance to a layer spin-coated from chlorinated solvents. This shows the potential of inkjet printing as a development and production tool for a variety of large area organic electronics.

At a site where groundwater is contaminated by chlorinated solvents, the spatial distribution of contamination and the persistence of the contamination over time is controlled by the interaction between the rate of natural attenuation in groundwater and the rate of natural attenuation of the source. Recent advances make it possible to describe and forecast the rate of natural attenuation of the source. This information makes it possible at many sites to include attenuation of the sources as part of a natural attenuation remedy. At other sites it may be possible to optimize the extent of active remediation of the source that is necessary to achieve a final remedy at a site.

Remediation of chlorinated solvent source zones remains extraordinarily challenging today and further advances will require the coordinated efforts of experts from a wide range of scientific disciplines including mathematics, chemistry, geology, hydraulics, geochemistry, microbiology and engineering. Research and development has played a vital role in improving site remediation efforts over the past 30 years and it will continue to be essential in the future. This chapter discusses research needs for both site characterization and remediation, as well as technology transfer needs. Many of the specific research needs identified in this chapter stem from discussions during Research and Development Needs meetings held in Washington, D.C. in 2010 and 2011, and subsequent written contributions.

Methyl chloroform (MCF) is a man-made chlorinated solvent contributing to the destruction of stratospheric ozone and is controlled under the "Montreal Protocol on Substances that Deplete the Ozone Layer" and its amendments, which called for its phase-out in 1996 in developed countries and 2015 in developing countries. Long-term, high-frequency observations of MCF carried out at three European sites show a constant decline in the background mixing ratios of MCF. However, we observe persistent non-negligible mixing ratio enhancements of MCF in pollution episodes, suggesting unexpectedly high ongoing emissions in Europe. In order to identify the source regions and to give an estimate of the magnitude of such emissions, we have used a Bayesian inversion method and a point source analysis, based on high-frequency long-term observations at the three European sites. The inversion identified southeastern France (SEF) as a region with enhanced MCF emissions. This estimate was confirmed by the point source analysis. We performed this analysis using an 11-year data set, from January 2002 to December 2012. Overall, emissions estimated for the European study domain decreased nearly exponentially from 1.1 Gg yr−1 in 2002 to 0.32 Gg yr−1 in 2012, of which the estimated emissions from the SEF region accounted for 0.49 Gg yr−1 in 2002 and 0.20 Gg yr−1 in 2012. The European estimates are a significant fraction of the total semi-hemisphere (30–90° N) emissions, contributing a minimum of 9.8% in 2004 and a maximum of 33.7% in 2011, of which on average 50% are from the SEF region. On the global scale, the SEF region is thus responsible for a minimum of 2.6% (in 2003) and a maximum of 10.3% (in 2009) of the global MCF emissions.

This chapter presents a technology description of in situ chemical oxidation (ISCO) and discusses the key concepts associated with its use for remediation of chlorinated solvent dense nonaqueous phase liquid (DNAPL) source zones. A variety of oxidants are discussed including hydrogen peroxide, potassium permanganate, sodium persulfate and ozone. Current practices along with remedial design issues and approaches for application of ISCO to DNAPL source zones are described, including monitoring and optimization strategies. This chapter concludes with a discussion of emerging approaches and technologies, and a discussion of research needs and breakthrough areas.

In situ chemical reduction (ISCR) is a general term for a suite of in situ groundwater remediation technologies that rely primarily on chemical reduction of contaminants. ISCR has been used for over 15 years for plume treatment, but its use for source treatment is more recent. This chapter provides the first integrated assessment of the entire suite of ISCR technologies, and describes the technical basis, engineering aspects, past experiences and future prospects for using ISCR to treat chlorinated solvent source zones. In situ chemical reduction of contaminants can occur through natural intrinsic biogeochemical processes, as a result of stimulating in situ microbial activity to form reducing minerals, or after direct injection of chemical reductants. The chapter includes case studies of several ISCR technologies and summarizes the lessons learned to date from research and field experience.

Some contaminated sites (including many of those with chlorinated solvent source zones) can be so complex that restoration in a reasonable time frame is not a realistic goal. This chapter summarizes the management challenges at highly complex sites, and provides several examples of measures taken in response to these challenges. One management approach that may be helpful at complex sites is the use of alternative endpoints, which either waive or substitute for long term cleanup standards, and are designed to ensure protectiveness while acknowledging the technical challenges. These alternative endpoints are described in this chapter, with several relevant examples of their use. In most cases, an integrated strategy is essential to manage these sites efficiently, and the chapter provides examples of ways to combine different approaches into an efficient integrated strategy.

The vertical heterogeneity of contaminant concentrations in aquifers is well known, but obtaining representative samples is still a subject of debate. In this paper, the question arises from sites where numerous fully screened wells exist and there is a need to define the vertical distribution of contaminants. For this purpose, several wells were investigated with different techniques on a site contaminated with chlorinated solvents. A core-bored well shows that a tetrachloroethene (PCE) phase is sitting on and infiltrating a less permeable layer. Downstream of the cored well, the following sampling techniques were compared on fully screened wells: low flow pumping at several depths, pumping between packers and a new multilevel sampler for fully screened wells. Concerning low flow rate pumping, very low gradients were found, which may be due to the existence of vertical flow inside the well or in the gravel pack. Sampling between packers gave results comparable with the cores, separating a layer with PCE and trichloroethene from another one with cis 1,2-dichloroethene and vinyl chloride as major compounds. Detailed sampling according to pumped volume shows that even between packers, cleaning of the inter-packer volume is necessary before each sampling. Lastly, the proposed new multilevel sampler gives results similar to the packers but has the advantages of much faster sampling and a constant vertical positioning, which is fairly important for long-term monitoring in highly stratified aquifers.

Palladized nanoscale zerovalent iron (Pd/NZVI) has been utilized for source zone control, yet the reductant responsible for pollutant transformation and the optimal conditions for subsurface application remain poorly understood. Here, trends in Pd/Fe reactivity toward 1,1,1,2-tetrachloroethane (1,1,1,2-TeCA) and cis-dichloroethene (cis-DCE) were compared in H2O and D2O batch systems as a function of pH, chlorinated solvent concentration, Pd surface loading, Pd/Fe mass loading, Pd/Fe aging time, and zerovalent iron [Fe(0)] particle size. For Pd/NZVI, the solvent kinetic isotope effect [i.e., kobs(H2O)/kobs(D2O) or SKIE] for 1,1,1,2-TeCA and cis-DCE reduction increased substantially with Pd loading and Pd/NZVI concentration, evidence that multiple pathways exist for chlorinated solvent reduction. At low Pd loadings and Pd/NZVI concentrations with relatively small SKIEs (less than ~5), we propose that modest reactivity enhancements (≤ 10-fold) reflect more efficient electron transfer to 1,1,1,2-TeCA from Fe(0) facilitated by Pd nanodeposits. Much larger SKIEs (e.g., exceeding 100 for cis-DCE) imply the involvement of atomic hydrogen in more reactive systems with high Pd loadings and Pd/NZVI concentrations. Generally, evidence of SKIEs supporting a dominant role for atomic hydrogen was not observed for Pd/Fe prepared from micrometer-sized Fe(0), or for any size of nonpalladized Fe(0). During anaerobic aging of Pd/NZVI, decreases in the SKIE for 1,1,1,2-TeCA reduction suggest that atomic hydrogen will contribute to reactivity for only approximately 1 week after application.

A multi-component GPR antenna is used to perform time-lapse measurements in a controlled experiment simulating DNAPL release. The DNAPL monitoring is based on the delay time of a reflection from the back side of a cell and on spectral analysis of traces. The study shows that co-polar and cross-polar antennas detect a similar pull-up of the reflection from the back of the cell induced by the DNAPL. The amplitude of the reflection from the DNAPL is weaker in the cross-polar data with respect to the co-polar data and in actual cases it could not be detected by both antenna configurations. In addition we observe a change in the amplitude spectra of the traces collected at the DNAPL release with respect to those collected in an uncontaminated area. The amplitude spectrum variations occurred mainly in the co-polar antennas. The spectra of cross-polar antennas show variations over time that are not easily linked to the DNAPL position. We observed that the data collected 141 hours after the first DNAPL injection and two hours of water flow, show a pull-up of the reflection from the back of the cell and variations in the amplitude spectra of the traces located at the same position as the DNAPL injection. This suggests that the DNAPL probably remained trapped by sediments and was not totally removed by the water flow. Forward models, simulating the experiment, confirmed that the DNAPL induces a pull-up of the reflection from the back of cell and showed that in a controlled experiment the DNAPL produces a reflection whose amplitude depends on the DNAPL saturation. In a real case the presence of small amounts of DNAPL can be at best barely visible because of induced small amplitude reflections. This is truer if no GPR data are available from before the DNAPL spill, so there is little chance that GPR responses can be positively attributed to DNAPL presence.

The reactions of M′O(acac)2 [M′ = Ti, V; acac = acetylacetonato anion] with equimolar amounts of MF5 (M = Nb, Ta) in CH2Cl2 afforded Ti(acac)2F2, 1a, and [V(acac)3][MF6] (M = Nb, 4a; M = Ta, 4b), respectively. MOF3 (M = Nb, 2a; M = Ta, 2b) were co-produced from MF5/TiO(acac)2. The intermediate species [TaF4{OTi(acac)2}2][TaF6], 3, was intercepted in the course of the formation of 1a from TiO(acac)2/TaF5. NbCl5 reacted with TiO(acac)2 yielding selectively the previously reported [NbO(acac)Cl2]x, 5, and Ti2(acac)2(μ-Cl)2Cl4, 6. Complex 6 was alternatively obtained from the addition of a two-fold excess of TiCl4 to VO(acac)2. The 1:1 reactions of TiX4 (X = F, Cl) with TiO(acac)2 in dichloromethane gave Ti(acac)2X2 (X = F, 1a; X = Cl, 1b) and TiOX2 (X = F, 7a; X = Cl, 7b). The 1:1 combination of TiX4 (X = F, Cl) with VO(acac)2 led to 1a,b and VOX2 (X = F, 8a; X = Cl, 8b). The μ-oxido compounds (C6F5)3B–O–M′(acac)2 (M′ = Ti, V) underwent fragmentation by [PF6]− in chlorinated solvent, yielding POF3, 9, and [B(C6F5)3F]−, 10, according to NMR studies; 1a and V(acac)3(+), respectively, were detected as the metal-containing species. Electrochemical studies were carried out aiming at the full characterization of the products and the observation of possible degradation pathways.