<p>Ekolo&scaron;ki&nbsp; problem&nbsp; svetskih&nbsp; razmera&nbsp; predstavlja&nbsp; zagađenost&nbsp; sedimenta&nbsp; te&scaron;kim&nbsp; metalima, usled negativnih ekolo&scaron;kih efekata metala na životnu sredinu. Mnoge zemlje i regioni, kao i na&scaron;a zemlja&nbsp; suočavaju&nbsp; se&nbsp; sa&nbsp; ovom&nbsp; problematikom,&nbsp; koja&nbsp; je&nbsp; vrlo&nbsp; rasprostranjena&nbsp; usled&nbsp; sve&nbsp; brže urbanizacije&nbsp; i&nbsp; industrijalizacije,&nbsp; a&nbsp; sa&nbsp; sve&nbsp; većom&nbsp; nebrigom&nbsp; usled&nbsp; ispu&scaron;tanja&nbsp; otpadnih&nbsp; voda&nbsp; bez prethodnog&nbsp; preči&scaron;ćavanja&nbsp; u&nbsp; vodotokove.&nbsp; Prilikom&nbsp; promene&nbsp; uslova&nbsp; vodenog&nbsp; ekosistema,&nbsp; može doći do&nbsp; izluživanja&nbsp; metala&nbsp; i &scaron;tetnih efekata na&nbsp; životnu sredinu kao&nbsp; i&nbsp; na zdravlje&nbsp; ljudi. Stoga je remedijacija sedimenata zagađenih metalima ključna aktivnost u okviru procesa potpune sanacije vodenog ekosistema, a ekonomične, efikasne i ekolo&scaron;ki prihvatljive tehnike remedijacije su hitno potrebne&nbsp; i&nbsp; rado&nbsp; primenljive&nbsp; u&nbsp; tretmanu&nbsp; na&nbsp; velikoj&nbsp; skali.&nbsp; Pre&nbsp; primene&nbsp; remedijacione&nbsp; tehnike&nbsp; na velikoj skali, neophodna su ispitivanja pri laboratorijskim uslovima i pilot skali.&nbsp; Na kraju svakog uspe&scaron;nog&nbsp; laboratorijskog&nbsp; ispitivanja&nbsp; nalaze&nbsp; se&nbsp; pilot&nbsp; istraživanja.&nbsp; Pomoću&nbsp; njih&nbsp; se&nbsp; dobija&nbsp; p ravi odgovor u smislu izbora optimalne tehnologije imajući u vidu investicione i operativne tro&scaron;kove,<br />postignuti rezultat i krajnje ciljeve u pogledu upravljanja postrojenjem i otpadom. U ovom radu ispitan&nbsp; je&nbsp; potencijal&nbsp; primene&nbsp; stabilisanog&nbsp; i&nbsp; zelenom&nbsp; sinte zom&nbsp; produkovanog&nbsp; nano&nbsp; Fe(0)&nbsp; zaremedijaciju&nbsp; sedimenta&nbsp; zagađenog&nbsp; te&scaron;kim&nbsp; metalima.&nbsp; Kao&nbsp; remedijaciona&nbsp; tehnika&nbsp; odabrana&nbsp; je stabilizacija/solidifikacija,&nbsp; koja&nbsp; podrazumeva&nbsp; dodavanje&nbsp; agenasa&nbsp; za&nbsp; imobilizaciju&nbsp; metala&nbsp; u sedimentu&nbsp; sprečavajući&nbsp; time&nbsp; potencijalni&nbsp; rizik&nbsp;&nbsp; od&nbsp; izluživanja&nbsp; metala&nbsp; u&nbsp; životnu&nbsp; sredinu. Konvencionalni&nbsp; materijali&nbsp; poput&nbsp; letećeg&nbsp; pepela,&nbsp; cementa,&nbsp; gline&nbsp; se&nbsp; već&nbsp; odavno&nbsp; koriste&nbsp; u&nbsp; ovu svrhu. Kako u dana&scaron;nje vreme raste potražnja za novim, lako dostupnim agensima za stabilizaciju<br />sedimenta, do&scaron;lo se na ideju o primeni nanomaterijala na bazi gvožđa, tj. nano Fe(0) stabilisanog nativnom glinom&nbsp; i produkovanog redukcijom pomoću organskih&nbsp; molekula prirodno prisutnih u ekstraktu&nbsp; li&scaron;ća&nbsp; hrasta&nbsp; i&nbsp; crnog&nbsp; duda.&nbsp; Nanomaterijali&nbsp; su&nbsp; sintetisani&nbsp; i&nbsp; karakterisani&nbsp; različitim metodama&nbsp; i&nbsp; tehnikama.&nbsp; U&nbsp; nastavaku,&nbsp; u&nbsp; cilju&nbsp; efikasnosti&nbsp; njihove&nbsp; primene&nbsp; za&nbsp; stabilizaciju sedimenta, sprovedeni su ekstrakcioni i dinamički laboratorijski testovi izluživanja. Odabrane su sme&scaron;e sedimenta i nanomaterijala koje su pokazale najbolju efikasnost tr etmana. Nakon toga se ispitivanje&nbsp; nastavilo&nbsp; na&nbsp; pilot&nbsp; skali,&nbsp; gde&nbsp; se&nbsp; pratilo&nbsp; pona&scaron;anje&nbsp; nanomaterijala&nbsp; u&nbsp; zavisnosti&nbsp; od konvencionalnih&nbsp; materijala&nbsp; koji&nbsp; su&nbsp; već&nbsp; u&nbsp; literaturi&nbsp; dokumentovani&nbsp; kao&nbsp; efikasni&nbsp; imobilizacioni agensi. Dodatna potvrda uspe&scaron;nosti tretmana data je analizom i karakterizacijom s/s sme&scaron;a nakon pilot&nbsp; ispitivanja&nbsp; Na&nbsp; osnovu&nbsp; dobijenih&nbsp; rezultata&nbsp; proces&nbsp; se&nbsp; uspe&scaron;no&nbsp; pokazao&nbsp; pri&nbsp; laboratorijskim uslovima,&nbsp; a&nbsp; takođe&nbsp; i&nbsp; prilikom&nbsp; pilot&nbsp; tretmana,&nbsp; odnosno&nbsp; nakon&nbsp; pilot&nbsp; tretmana&nbsp; nije&nbsp; do&scaron;lo&nbsp; do povećanih koncentracija&nbsp; izluživanja metala iz s/s sme&scaron;a, kao ni degradacije sme&scaron;a nakon procesa ovlaživanja&nbsp; tokom&nbsp; &scaron;est&nbsp; meseci.&nbsp; Na&nbsp; osnovu&nbsp; toga,&nbsp; ovako&nbsp; tertirani&nbsp; sediment&nbsp; se&nbsp; može&nbsp; bezbedno odlagati&nbsp; na&nbsp; deponije,&nbsp; ili&nbsp; pak&nbsp; iskoristiti&nbsp; za&nbsp; &bdquo;kontrolisanu&ldquo;&nbsp; upotrebu,&nbsp; izgradnju&nbsp; puteva,kamenoloma, pomoćnih objekata i slično. Rezultati su doprineli u cilju trajnijeg re&scaron;avanja pitanja odlaganja&nbsp; zagađenog&nbsp; (izmuljenog)&nbsp; rečnog&nbsp; sedimenta,&nbsp; pri&nbsp; čemu&nbsp; se&nbsp; u&nbsp; procesu stabilizacije/solidifikacije&nbsp; dobijaju&nbsp; proizvodi&nbsp; sa&nbsp; dodatom&nbsp; vredno&scaron;ću&nbsp; neumanjenog&nbsp; kvaliteta .Nanomaterijali sintetisani u ovom radu na&nbsp; bazi ekstrakta li&scaron;ća biljaka doprinose kako očuvanju životne&nbsp; sredine,&nbsp; tako&nbsp; i&nbsp; ekonomičnosti&nbsp; primene&nbsp; remedijacione&nbsp; tehnike.&nbsp; Zahvaljujući&nbsp; velikoj specifičnoj&nbsp; povr&scaron;ini,&nbsp; malim&nbsp; dimenzijama&nbsp; čestica&nbsp; i&nbsp; velikom&nbsp; kapacitetu&nbsp; za&nbsp; imobilizaciju&nbsp; te&scaron;kih<br />metala predstavljaju efikasnu alternativu komercijalno dostupnim materijalima, &scaron;to ih čini veoma atraktivnim&nbsp; i&nbsp; obećavajućim&nbsp; u&nbsp; budućnosti&nbsp; pri&nbsp; tretmanu&nbsp; rečnog&nbsp; sedimenta&nbsp; zagađenog&nbsp; te&scaron;kim metalima.</p> / <p>The pollution of sediment by heavy metals represents a large environmental problem all<br />over the world.&nbsp; A&nbsp; lot of countries&nbsp; in the region&nbsp; as well as our country deal with this problem, which&nbsp; is&nbsp; widespread&nbsp; because&nbsp; of&nbsp; the&nbsp; fast&nbsp; urbanization&nbsp; and&nbsp; industrialization.&nbsp; There&nbsp; is&nbsp; more&nbsp; and more&nbsp; carelessness&nbsp; about&nbsp; wastewater&nbsp; discharge&nbsp; into&nbsp; water&nbsp; flows&nbsp; without&nbsp; previous&nbsp; purification. When the conditions of the aquatic ecosystem change, metal leaching and harmful effects on the environment&nbsp; and&nbsp; human&nbsp; health&nbsp; can&nbsp; occur.&nbsp; Therefore,&nbsp; remediation&nbsp; of&nbsp; metal-contaminated sediments&nbsp; is&nbsp; crucial&nbsp; activity&nbsp; in&nbsp; the&nbsp; process&nbsp; of&nbsp; the&nbsp; complete&nbsp; ecosystem&nbsp; remediation.&nbsp; Cost effective, efficient and environmentally friendly remediation techniques are urgently needed and readily applicable in large-scale treatment. Before applying remediation techniques on the largescale,&nbsp; both&nbsp; laboratory&nbsp; and&nbsp; pilot&nbsp; tests&nbsp; are&nbsp; necessary.&nbsp; There&nbsp; are&nbsp; pilot&nbsp; studies&nbsp; at&nbsp; the&nbsp; end&nbsp; of&nbsp; each successful&nbsp; laboratory&nbsp; test.&nbsp; Those&nbsp; studies&nbsp; provide&nbsp; the&nbsp; right&nbsp; answer&nbsp; in&nbsp; terms&nbsp; of&nbsp; choosing&nbsp; the optimal technology, taking into account the investment and operating costs,&nbsp;&nbsp; the achieved resultand&nbsp; the&nbsp; ultimate&nbsp; goals&nbsp; in&nbsp; terms&nbsp; of&nbsp; plant&nbsp; and&nbsp; waste&nbsp; management.&nbsp; In&nbsp; this&nbsp; study,&nbsp; the&nbsp; application<br />potential of stabilized and green&nbsp; -&nbsp; synthesized&nbsp; nano Fe(0) for the remediation of&nbsp; heavy&nbsp; metal&nbsp; -contaminated&nbsp; sediment&nbsp; was&nbsp; investigated.&nbsp; Stabilization&nbsp; /&nbsp; solidification&nbsp; technique&nbsp; was&nbsp; chosen&nbsp; as remediation technique which involves the addition of metal immobilizing agents in the sediment thus preventing the potential risk of metal leaching into the environment. Conventional materials such as fly ash, cement and clay have long been used for this purpose. Nowadays there is need for new, easily accessible agents for the sediment stabilization. Therefore it came up with the idea of&nbsp; using&nbsp; iron-based&nbsp; nanomaterials,&nbsp; ie.&nbsp; nano&nbsp; Fe(0)&nbsp; stabilized&nbsp; by&nbsp; native&nbsp; cla y&nbsp; and&nbsp; produced&nbsp; by reduction&nbsp; using&nbsp; organic&nbsp; molecules&nbsp; naturally&nbsp; present&nbsp; in&nbsp; oak&nbsp; and&nbsp; black&nbsp; mulberry&nbsp; leaf&nbsp; extract. Nanomaterials have been synthesized and characterized by different methods and techniques. In order&nbsp; to&nbsp; be&nbsp; effective&nbsp; in&nbsp; their&nbsp; application&nbsp; for&nbsp; sediment&nbsp; stabilization,&nbsp; extraction&nbsp; and&nbsp; dynamic laboratory leaching tests were performed. Mixtures of sediment and nanomaterials were selected that showed the best treatment efficiency.&nbsp; After that, the examination was continued on a pilot scale, where the behavior of nanomaterials was monitored, depending on conventional materials which&nbsp; have&nbsp; already&nbsp; been&nbsp; documented&nbsp; in&nbsp; the&nbsp; literature&nbsp; as&nbsp; effective&nbsp; immobilizing&nbsp; agents.Additional confirmation of treatment success was given by analysis and characterization of s / s mixtures&nbsp; after&nbsp; pilot&nbsp; testing.&nbsp; According&nbsp; to&nbsp; obtained&nbsp; results,&nbsp; the&nbsp; process&nbsp; was&nbsp; successfully demonstrated&nbsp; under&nbsp; laboratory&nbsp; conditions,&nbsp; and&nbsp; also&nbsp; during&nbsp; the&nbsp; pilot&nbsp; treatment.&nbsp; After&nbsp; the&nbsp; pilot treatment&nbsp; there&nbsp; were&nbsp; no&nbsp; increased&nbsp; concentrations&nbsp; of&nbsp; metal&nbsp; leaching&nbsp; from&nbsp; s/s&nbsp; mixtures,&nbsp; nor mixture degradation after the wetting process for six months. Based on that, the sediment treated in this way&nbsp; can&nbsp; be safely disposed of&nbsp; in&nbsp; landfills, or used&nbsp; for &quot;controlled&quot; use, construction of<br />roads,&nbsp; quarries,&nbsp; auxiliary&nbsp; facilities&nbsp; and&nbsp; etc.&nbsp; The&nbsp; results&nbsp; have&nbsp; contributed&nbsp; to the&nbsp; goal&nbsp; of&nbsp; a&nbsp; more permanent solution to the issue of disposal of polluted (slugged) river sediment, whereby in the process&nbsp; of&nbsp; stabilization/solidification,&nbsp; products&nbsp; with&nbsp; added&nbsp; value&nbsp; of&nbsp; undiminished&nbsp; quality&nbsp; are obtained. The nanomaterials synthesized in this paper on the basis of plant leaf extract contribute to both the preservation of the environment and the economy of remediation techniques. Thanks to their&nbsp; large specific&nbsp; surface area, small particle size and&nbsp; large ca pacity&nbsp; for&nbsp; immobilization of heavy&nbsp; metals,&nbsp; they&nbsp; represent&nbsp; an&nbsp; effective&nbsp; alternative&nbsp; to&nbsp; commercially&nbsp; available&nbsp;&nbsp; materials.&nbsp; It makes&nbsp; them&nbsp; very&nbsp; attractive&nbsp; and&nbsp; promising&nbsp; in&nbsp; the&nbsp; future&nbsp; in&nbsp; the&nbsp; treatment&nbsp; of&nbsp; river&nbsp; sediment contaminated with heavy metals.</p>

Olefin metathesis is a powerful tool for the making and breaking of carbon-carbon double bonds. Among well-defined homogenous catalysts for olefin metathesis, ruthenium-based alkylidenes stand out for their robustness and relative ease-of-use. Synthesis of the most active Ru-based metathesis catalysts remains challenging, however, and there is continued interest in new and improved routes to alkylidene installation as metathesis begins to see wide uptake in industry. The first part of this thesis focuses on developing new routes to known catalysts. Magnesium carbenoids are investigated as a potential alkylidene source, and in the process a novel route to benzylmagnesium carbenoids is developed. Initially promising results showing ca. 40% conversion to first generation metathesis catalysts failed to lead to a viable high-yield route to Ru-alkylidenes. A high yield route to RuCl2(H2IMes)(py)4 (previously reported in low yields as a decomposition product of the third-generation Grubbs’ metathesis catalyst) is developed and this complex is investigated as a precursor to indenylidene-based catalysts. Although RuCl2(H2IMes)(py)4 is shown to be substitutionally labile, indenylidene installation could not be achieved. Finally, zinc aryloxides are investigated as an alternative to thallium and silver reagents for the installation of aryloxide ligands. Initial results indicate that zinc aryloxides are kinetically, though not thermodynamically, competent for the installation of the challenging aryloxide C6F5O- on the second-generation Hoveyda catalyst. The second part of this thesis concerns progress towards the development of a new low-valent catalyst platform. Initial experiments involving treating the second-generation Hoveyda catalyst with various reducing agents fail to produce low-valent alkylidenes, leading instead to decomposition of alkylidene. Drawing inspiration from early transition metal systems, the remainder of the second part focuses on alpha-hydride elimination from a RuII alkyl as a means of accessing low-valent alkylidenes. To this end, a novel benzylruthenium complex as well as bis-benzyl and mono-aryloxide derivatives are developed. While attempts to induce benzyl-to-benzyl hydride abstraction or intramolecular deprotonation of the benzyl ligand failed to produce alkylidenes, ligand-induced benzyl-to-aryloxide hydride abstraction appears to be successful, leading to the observation of a broad 1H NMR signal in the region characteristic for low-valent Ru-alkylidenes.

No description available.

For centuries chemists have sought to improve humankind’s quality of life and address many of society’s most pressing needs through the development of chemical processes and synthesis of new compounds, often with phenomenal results. Unfortunately, there also are many examples where these chemicals have had unintended, detrimental consequences that are not apparent until years or decades after their initial use. There are numerous halogenated molecules in this category that are globally dispersed, resistant to natural degradation processes, bioaccumulative, and toxic to living organisms. Chemicals such as these are classified as persistent organic pollutants (POPs), and due to their negative environmental and health effects, they require safe, effective, and inexpensive means of remediation. This research focuses on the development and optimization of a reaction matrix capable of reductively dehalogenating several POPs. Initial experiments determined that powdered magnesium and 1% V/V acetic acid in absolute ethanol was the most effective system for degrading polychlorinated biphenyl (PCB), an extraordinarily recalcitrant environmental contaminant. Further studies showed that this matrix also was capable of degrading polychlorinated dibenzo-p-dioxins (PCDDs), polybrominated diphenyl ethers (PBDEs), and four organochlorine pesticides (OCPs); dieldrin, heptachlor, heptachlor epoxide, and chlordane. During this phase of testing, field samples contaminated with chlordane were washed with ethanol and this ethanol/chlordane solution was degraded using the same reaction matrix, thereby demonstrating this technology’s potential for “real-world” remediation projects. Finally, a set of experiments designed to provide some insight into the mechanism of dechlorination seems to indicate that two distinct processes are necessary for degradation to occur. First, the passivated iv outer layer of the magnesium must be removed in order to expose the zero-valent magnesium core. Next, an electron is transferred from the magnesium to the target molecule, causing the cleavage of the halide bond and the subsequent abstraction of either a hydrogen or proton from a solvent molecule. It is anticipated that an understanding of these fundamental chemical processes will allow this system to be tailored to a wide range of complex environmental media

Heavy metal contamination of soils, sediments and groundwater presents an ongoing source of hazardous and persistent environmental pollution. How best to remediate these contaminants is the impetus of continuing research efforts. Methods include containment, ex situ and in situ techniques. A successful in situ method utilizing a combination of emulsified liquid membranes, ELM, and zero-valent metal, ZVM, and bimetals has demonstrated impressive heavy metal reduction in 100 ppm solutions of Cd, Cu, Ni, Pb, Cr and U. This promising in situ method has been employed by the Industrial Chemistry Laboratory at the University of Central Florida and it has demonstrated considerable success in treating several environmental threats. Contaminated soils, surfaces, sediments and groundwater with offending agents such as trichloroethene, polychorobiphenyls and heavy metals have been treated utilizing emulsified liquid membrane systems containing zero-valent iron or bimetal particles. In vial studies, lead spiked sediments have shown repeatable 60% removal of lead after seven days of treatment. A persistent pattern emerged at ten days whereupon remediation levels began to drop. The current study was established to determine the reason for the decline at ten days and beyond. Questions addressed: Does the formation of an impeding oxide layer diminish the remediation capacity of the iron/magnesium system? Does the emulsion reach a maximum capacity to withdraw the contaminant? Do the soil components or the soil structure interfere with the access to the contaminant? This study has yielded insight into the reasons emulsified liquid membrane systems containing zero-valent metals achieved maximum lead removal at day seven, and thereafter begin to lose their effectiveness. A three part study was implemented to address and to answer the three questions pertaining to the consistent pattern of diminishing remediation levels exhibited at day ten and beyond. Initially, from Study I results it appeared that the formation of an impeding oxide layer on the bi-metal which was inside the emulsion droplet and which plated or precipitated with the lead was not occurring at day ten. Results indicated that the iron/magnesium was still capable of removing lead. Furthermore, from Study II results the emulsion dose injected appeared adequate to remove the lead, meaning that the emulsion had not reached its maximum capacity for remediation. The emulsion dose was not a limiting factor. Lastly, Study III results seemed to indicate that the drop in remediation after day seven pertained to the soil structure. There appeared to be some merit to the idea that with aging of the sediment, the lead was diffusing and migrating to some inaccessible interior sites within the sediment particles. Additionally, indications from day ten and day fourteen delineated that a second emulsion dose injection might restore lead removal levels to approach those first observed at day seven and consequently be a useful field application. In order to explore the effectiveness of injecting a second dose of emulsion, another vial study was implemented. The typical pattern of observing sixty percent maximum lead removal at day seven was observed. In separate groups, a second injection of emulsion was added at day five, and then for another vial series, a second dose was added at day seven. The second emulsion dose treatment for either day five or day seven did not yield any increases in percent lead removal. Another theory emerged after viewing micrographs of recovered iron/magnesium compared with fresh ball-milled bimetal. In addition, scanning electron microscopy appeared to confirm the explanation that the emulsified zero-valent metal system might be compromised after day seven. This would lead to exposure of the iron/magnesium to the air and the elements. Corrosion of the bimetal might be occurring. With time, release of the plated or precipitated lead back into the sediment mixture could follow. The results of Study I had led to the conclusion that an impeding oxide layer had not formed; however, this conclusion may have been premature because the recovered iron/magnesium was exposed to lead solution in the vial study. Perhaps if the recovered iron/magnesium was inserted back into an emulsion and injected into lead spiked sediments the percent lead removed might give a more accurate picture of the iron/magnesium's capability to continue performing remediation. Remediation of sediments contaminated with lead is a complicated task because of the complex nature of sediment components. Emulsified liquid membranes utilizing zero-valent bimetals has repeatedly demonstrated impressive results at day seven; however, this treatment method is not without its limitations. Optimal results appear to be gained at day seven after emulsion injection. The bimetal and plated or precipitated lead must be removed at that point; otherwise the effective remediation of the contaminant is progressively reversed.

Polychlorinated biphenyls are a ubiquitous environmental contaminant that can be found today throughout the world in soils and sediments, lakes and rivers, and flora and fauna. PCBs have percolated throughout the food chain, so that almost every human being has a detectable amount of the contaminant within their blood stream. Existing remediation methods include incineration, dredging and landfilling, and microbial degradation, but all of these methods have drawbacks that limit their effectiveness as treatment options. Recently, the use of zero-valent metals as a means of reductive dechlorination has been explored. Using a combination of zero-valent magnesium and catalytic palladium, a successful bimetallic system capable of degrading PCBs has been created and optimized. Determining the mechanism for the reductive dechlorination has proven to be an arduous task, but experimental evidence has suggested three possible radical-type mechanisms for the use Mg/Pd specifically in methanol (as compared to aqueous systems). These possible mechanisms differ in the type of hydrogen species that replaces the chlorine atom on the PCB. Thermodynamic information has also aided in narrowing down which of the suggested pathways is most likely. It appears likely that the hydrogen involved in the dechlorination has the form of a "hydride-like" radical, which is a form of electron-rich atomic hydrogen. According to the literature, Pd catalysts create this species within the first few subsurface layers of the palladium in the presence of molecular hydrogen. Further work will be necessary to confirm that the "hydride-like" radical is actually the species involved in the dechlorination.

No description available.

The Department of Defense (DoD) has numerous sites that contain groundwater contaminated with 2,4,6-trinitrotoluene (TNT). The currently applied technologies for treating TNT contaminated waters are carbon adsorption and chemical oxidation. Carbon adsorption is a non-destructive technology, which could create future liability issues and is inefficient at relatively low TNT concentrations. On the other hand, application of chemical oxidation for the treatment of TNT contaminated water generates trinitrobenzene (TNB), a by-product of the incomplete oxidation of TNT. TNB is regulated as strictly as TNT. Additionally, over 70% of the reactor required treatment time for meeting target levels is due solely for TNB removal. This study evaluated the potential integration of zero-valent metallic species and advanced oxidation for the treatment of waters contaminated with TNT. The idea was to reduce treatment time, and thus, operational costs, when advanced oxidation is used as a stand-alone treatment technology by reducing TNT prior to oxidation. The use of zero-valent metals as the first treatment step transformed TNT into reduced organic compounds which were easily oxidized. The effectiveness of zinc, iron, nickel, copper, and tin as TNT reducing agents was evaluated. Zinc and iron were selected for further study based on their performance degrading TNT. Then, the reduction mechanism (pathway) and associated by-products of TNT reduction using zinc were examined using a zinc specimen manufactured by Sigma Corporation. Three amines were identified during reduction : 2-amino-4,6-dinitrotoluene, 4-amino-2,6-dinitrotoluene, and 2,4-diamino-toluene. Other intermediates were observed but not identified. Many of these reduction by-products adsorbed strongly onto the metal surface, significantly reducing the rate of TNT degradation during aging experiments. The aging of the metallic species was modeled using a power decay law parameter with the rate expression for TNT degradation. Corrosion promoters such as KCl addition, ozonation, and peroxone were evaluated as alternatives to reactivate zinc and iron to achieve steady TNT degradation. The addition of KCl performed significantly better than ozonation and peroxone. Furthermore, addition of KCl during the reduction step using iron or zinc generated organics that were successfully mineralized by ozonation or peroxone.

No description available.

No description available.