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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
91

Monitoring the Effects of Chlorination Treatment on Sulfamethazine using LCMS-IT-TOF

Melton, Tyler, Brown, Stacy D. 01 October 2011 (has links)
No description available.
92

New methods and reagents for small scale synthesis of phosphor organic compounds with focus on the phosphonic acids and their analogues

Wärme, Rikard January 2010 (has links)
The development of a synthetic method of radiolabelled methylphosphono-fluoridates on a milligram scale is presented. The aim of this method is, besides affording high yield, to choose reaction pathways and reagents so that handling and transfer of labelled toxic substances is minimised, thereby reducing the risk of exposure as much as possible. The only substituent that is stable enough to be labelled is the methyl group, directly bonded to phosphorus. A drawback when labelling the methyl group is that it requires the label to be introduced early in the synthesis since the carbon-phosphorus bond of the methyl substituent usually has to be synthesized a few steps ahead of the final product. Two new classes of reagents for halogenation of phosphorus oxyacids have been developed. Firstly, four different analogues of α-chloroenamines and α-fluoroenamines were evaluated. Secondly, cyanuric fluoride was assessed in solution, but more importantly, as a resin-bound reagent. The reagents are evaluated for halogenation of phosphinic, phosphonic and phosphoric acids. Cyanuric fluoride is also successfully loaded on a polystyrene resin and used as a solid-phase reagent. The reagents produce high yields and low levels of impurities on a milligram scale. Furthermore, a new method for the preparation of mono-alkylated phosphonic acids on a small scale has been developed. The new method utilises the crystal water bound to certain salts to liberate limited amounts of water in a controlled manner. Phosphonic dichlorides are in this way reacted with water to form anhydrides. The anhydride is then cleaved with an appropriate alcohol to produce mono-alkylated phosphonic acids. / Rikard Norlin = Rikard Wärme
93

Chlorination of organic material in different soil types

Gustavsson, Malin January 2009 (has links)
Research has shown that formation of chlorinated organic matter occurs naturally and that organic chlorine is as abundant as the chloride ion in organic soils. A large number of organisms are known to convert inorganic chloride (Clin) to organic chlorine (Clorg) (e.g. bacteria, lichen, fungi and algae) and some enzymes associated to these organisms are capable of chlorinating soil organic matter. The aim with the study was to compare organic matter chlorination rates in soils from several different locations dominated by either coniferous forest or pasture. Soil from eight samples sites in the southern of Sweden were incubated at 20°C with addition of 36Clin in a 138 days long radiotracer experiment. The results show that transformation of 36Clin to 36Clorg occurred and that the amounts of 36Clorg increased over time. The chlorination rate was higher in the samples from coniferous forest than in samples containing pasture soil, where the specific chlorination rate was 3-4 times smaller. This study contributes new information about chlorination in various soil types and soil from different locations in southern central Sweden. The similarity between the chlorination rates measured in coniferous forest soils so far indicate that up scaling to regional estimates may be less problematic than expected.
94

Chemistry of an oxidative alkaline extraction between chlorine dioxide stages

Runge, Troy M. 05 November 1998 (has links)
No description available.
95

Disinfection By-products Formation In Low - Bromide And Low - Suva Waters

Ates, Nuray 01 May 2008 (has links) (PDF)
The main objective of this study was to conduct a systematic investigation of the disinfection by-products (DBPs) formation in low-bromide and low- specific ultraviolet absorbance (SUVA) waters and the control of DBP precursors by nanofiltration (NF) and ultrafiltration (UF) processes in such waters. To this end, firstly, the effect of bromide ion on the formation and speciation of DBPs was investigated. In fractionated Alibeyk&ouml / y source water, increasing bromide concentrations in NOM fractions increased concentrations of trihalomethanes (THMs), haloacetic acids (HAAs) and adsorbable organic halides (AOX) and resulted in a shift toward the formation of brominated species. Secondly, the impacts of SUVA and differential UV spectroscopy (&amp / #916 / UV), which has been shown to correlate well with DBP formation has been elucidated in terms of DBP formation and speciation. Alibeyk&ouml / y and Karaca&ouml / ren waters were fractionated employing various separation methods and it has been shown that SUVA did not correlate well with the formation and speciation of THMs and HAAs in tested low-SUVA waters. Similarly, no correlations were found among THMs/HAAs formations and &amp / #916 / UV. Finally, the NOM rejection performances of NF and UF membranes were investigated. NF and UF membranes (&lt / 2000 dalton) was found to be suitable for the removal NOM from surface waters having low SUVA and low bromide contents. While higher molecular weight (HMW) fraction was successfully rejected (&gt / 90%) by all membrane types, lower molecular weight (LMW) fraction could be removed with ranging efficiencies from 1.5 to 30%. NF membranes provided DOC, UV254 absorbance, THM, and HAA reductions up to 90%.
96

From chlorinated transformation products to highly hydrated ions with electrospray ionization mass spectrometry

Pape, Jennifer Lynn 26 May 2011 (has links)
Pharmaceutical and personal care products (PPCPs) triclosan and nonylphenol, were investigated throughout wastewater treatment in a publicly owned treatment works (POTW). Both compounds react quickly upon chlorination under laboratory conditions, transforming into mono and dichlorinated species. A novel quantitative analytical method employing mass spectrometry was demonstrated on Delaware POTW wastewater samples. Specific transformation products were not detected and the concentration of precursor analytes was not found to be statistically different after treatment. Under tertiary chlorination conditions, transformation products are not produced. ESI-MS was used to explore triply charged, highly hydrated lanthanide ions and charge reduction was directly observed in the MS collision cell. This process proceeded via proton transfer, proved by a strong correlation between the minimum number of water molecules required to stabilize the Ln3+ and the first hydrolysis constant (R2=0.92). The effect of different solvents on the surface activity of ions under electrospray ionization (ESI) was investigated using dilute ionic liquids and the relative surface activity of a given pair of ions could be reversed by moving from a relatively polar solvent to a relatively non-polar one. / Graduate
97

Oxidation Behavior and Chlorination Treatment to Improve Oxidation Resistance of Nb-Mo-Si-B Alloys

Vikas Behrani January 2004 (has links)
19 Dec 2004. / Published through the Information Bridge: DOE Scientific and Technical Information. "IS-T 2315" Vikas Behrani. 12/19/2004. Report is also available in paper and microfiche from NTIS.
98

Étude du chlore organique dans les sols et de sa formation en conditions biotiques et abiotiques / Study of organic chlorine in soils and formation in biotic and abiotic conditions

Osswald, Aurélie 06 July 2016 (has links)
Des études ont démontré que du chlore organique est retenu dans les sols et serait formé par un processus de chloruration issu de l’activité microbienne des sols. Le but de cette étude est d’estimer les formes organiques de chlore dans des sols contrastés et de mettre en évidence l’évolution de ces formes de chlore selon certains paramètres environnementaux ou modalités d’incubations en fonction de l’activité des microorganismes. Les horizons organo-minéraux de sols contrastés ont été étudiés (i) in situ : Les quantités de chlore et les paramètres physico-chimiques et microbiologiques de sols ont été mesuré ; (ii) dans deux dispositifs d’incubations sous différentes modalités. Les mesures des teneurs en chlore entre le début et la fin de la première expérience ont été mesurées par analyseur d’AOX. Pour la deuxième expérience, les sols ont été enrichis en Na37Cl et les teneurs en 37Cl ont été mesurées par ICP MS HR. Des mesures par spectrométrie Xanes ont été réalisées pour préciser la spéciation du chlore des sols. Les teneurs en chlore organique non extractibles représentent presque la totalité du chlore. Les paramètres qui influencent la répartition des teneurs en chlore correspondent au couvert végétal, au pH, à la teneur en carbone organique et aux quantités de microorganismes. Les teneurs en chlore mesurées par analyseur d’AOX et par ICP MS HR ont permis de mettre en évidence une formation de chlore organique en relation avec les paramètres microbiologiques. Les mesures par ICP MS HR ont montré une formation de chlore organique en conditions abiotiques. Les analyses par spectrométrie XANES n’ont pas permis de mettre en évidence une formation de chlore organique / Recent studies have shown that organic chlorine is retained in the soil and is formed by a chlorination process mainly from the microbial activity of the soi still poorly documented. The aim of this study is to estimate the organic and inorganic forms of chlorine in contrasting soil and highlight the evolution of these forms according to certain environmental parameters or terms of incubations and to the activity of microorganisms. For this, the organo-mineral horizons of contrasting soil were studied (i) in situ: The amounts of chlorine and physico-chemical and microbiological parameters of soil were measured; (ii) in two experimental devices incubations under different conditions. Measurements of chlorine levels between the beginning and the end of the first experiment were measured by AOX analyzer. For the second experiment, the soil was previously enriched with Na37Cl and 37Cl levels were measured by HR ICP MS. Soil samples from these incubations were analyzed by Xanes spectrometry to identify the speciation of chlorine forms in soils. Soil non-extractable organic chlorine contents represent almost all of the chlorine. The parameters that influence the distribution of chlorine contents in soils correspond to vegetation cover, pH, organic carbon content and quantities of microorganisms. The chlorine contents measured by AOX analyzer and by HR ICP MS highlight an organic chlorine formation over time in relation to the microorganims in the soil. The measures carried out by HR ICP MS show also an organic chlorine formation in abiotic conditions. Conversely, XANES spectrometry measurements have show any organic chlorine formation
99

Improving Activated Carbon Performance in Point Of Use and Municipal Processes

January 2018 (has links)
abstract: Specific inorganic and organic pollutants in water (As(V), Cr(VI), THMs, and hardness) cause health concerns or aesthetic problems. The goal of this dissertation is to demonstrate novel approaches to improve the performance of point of use and municipal activated carbon processes to provide safe and reliable water to the public at distributed centralized locations. Template Assisted Crystallization system would adjust saturation index (SI) value of TAC treated water to zero when SI value of influent water was in the range at 0.08~0.3. However, the reduction in SI when SI values were higher (e.g. 0.7~1.3) was similar to the reduction at lower SI values which could be due to limitations in kinetics or mass transfer with the template on TAC media. Pre-chlorination prior to municipal-scale granular activated carbon (GAC) treatment was evaluated to control THM formation in distribution systems. Pre-chlorination decreased UVA, shift the dissolved organic carbon (DOC) molecular weight distribution and pre-formed trihalomethanes (THM). GAC treatment of pre-chlorinated water achieved lower THM formation in distribution systems. To add functionality in POU systems to remove As(V) and Cr(VI), activated carbon was nano-tized to fabricate nano-enabled carbon block (CB) by (1) impregnating iron or titanium metal oxides chemically or (2) attaching titanium based P25 through electrostatic attraction force. Nanoparticle loadings of 5 to 10 wt % with respect to activated carbon enables reduction of As(V) or Cr(VI) from levels of common occurrence to below regulatory levels across carbon block designs. Minimal impacts on As(V) and Cr(VI) sorption were observed up to a nanoparticle pre-treatment temperature of 200 C, which is the temperature for CB production. Through controlling pH at 4.5 during mixing of nanoparticles with pH IEP=6 and activated carbon with pH IEP=3, electrostatic attachment of nanoparticles to activated carbon could be achieved prior to fabricating carbon block. A mini carbon block test device was designed, fabricated, and validated to mimic performances of full-scale carbon block using less volumes of test water. As(V) removal tests showed Fe impregnated CB achieved the highest As(V) removal while P25 attached CB had the lowest among three nanoparticles loaded CBs. / Dissertation/Thesis / Doctoral Dissertation Civil, Environmental and Sustainable Engineering 2018
100

Investigação da toxicidade, tratabilidade e formação de subprodutos tóxicos em efluentes clorados de lagoas de estabilização com e sem pós-tratamento. / Investigation of toxicity, treatability and toxic disinfection by-products formation in chlorinated stabilization ponds effluents with and without post-treatment.

Luís Fernando Rossi Léo 16 April 2008 (has links)
Entre as principais dificuldades que os sistemas de tratamento de esgotos domésticos compostos por lagoas de estabilização enfrentam para atender as exigências impostas pela Resolução CONAMA 357/2005 podem se destacar as concentrações elevadas de nitrogênio amoniacal, fósforo e coliformes fecais e totais. Estes últimos, quando os sistemas utilizam corpos receptores classe 2 ou 3 geram a necessidade de desinfecção. Dentre as diversas tecnologias disponíveis para a desinfecção dos esgotos, a cloração é bastante atrativa pelo custo reduzido, em relação às outras tecnologias, bem como pela elevada experiência que as companhias e municipalidades possuem neste tipo de sistema, advinda dos sistemas de tratamento de água. Dentre os sistemas de cloração, o uso de hipoclorito de sódio torna-se interessante pela segurança, simplicidade das instalações e de operação. A desvantagem do uso deste tipo de sistema se dá na possibilidade da formação de subprodutos tóxicos, dentro os quais pode-se destacar os trihalometanos (THMs) e os ácidos haloacéticos (AHAs), porém esta formação pode ser teoricamente reduzida pela presença de elevadas concentrações de nitrogênio amoniacal nos efluentes destes sistemas, por sua reação preferencial com o cloro, na formação de cloraminas. Outras possibilidades de redução na formação é reduzir a concentração de precursores, reduzir a dosagem de cloro e utilizar método de descloração dos efluentes após a desinfecção. Este trabalho, ambientado no desenvolvimento das pesquisas do Edital 4 do PROSAB/FINEP (Programa Nacional de Pesquisa em Saneamento Básico), desenvolveu testes de desinfecção em efluentes de lagoas anaeróbias e facultativas utilizando como desinfetante hipoclorito de sódio, em dosagens de 8,0 mgCl/L e 12,0 mgCl/L. Desenvolveu também testes de desinfecção com efluentes anaeróbios e facultativos pós-tratados por meio de coagulação/floculação/sedimentação e coagulação/floculação/flotação com ar dissolvido, com dosagens de 2,0 mgCl/L e 4,0 mgCl/L. Para todos os testes de desinfecção foram realizados também testes de descloração das amostras. Desta forma foi possível estudar, dentro de uma faixa limitada, as possibilidades de reduzir a formação de subprodutos tóxicos na desinfecção de efluentes de lagoas de estabilização com hipoclorito de sódio. Nas amostras foram determinados por meio de cromatografia gasosa as concentrações dos THMs e AHAs. Por meio das metodologias do Standard Methods 20th Edition foram realizadas as análises físico-químicas dos parâmetros pH, temperatura, DQO, DBO, Ntotal, N-NH3, NTK, cloro livre, cloraminas, coliformes e outros microrganismos indicadores. A formação de THMs se mostrou bastante pequena, em média abaixo dos 20,0 µg/L em todos os testes, aparentemente devido às elevadas concentrações de N-NH3, da ordem de 30,0 mg/L. O mesmo não ocorreu com os AHAs. Em muitos testes a concentração encontrada de AHAs totais superou o padrão de 80,0 µg/L preconizados pela USEPA para água potável, e aqui adotado como padrão comparativo. A descloração reduziu em média 52% a concentração de AHAs nos testes, colocando quase todas as amostras dentro do padrão de 80,0 µg/L. Os bioensaios mostraram que a presença de cloro livre nas amostras eleva a toxicidade aguda em Daphnia similis provocada pelos efluentes e que a cloração seguida de descloração produz efluentes com toxicidade inferior à toxicidade dos efluentes apenas clorados e toxicidade também inferior àquela dos efluentes sem cloração. / The main difficulties that the stabilization ponds for sewage treatment systems face to meet the requirements imposed by CONAMA Resolution 357/2005 can highlight the high concentrations of ammonia nitrogen, phosphorus and fecal and total coliform. When the systems use receivers water bodies Class 2 or 3 generate the need for disinfection. Among the different technologies available for the disinfection of sewage, the chlorination is very attractive at reduced cost compared to other technologies, as well as the high experience that companies and municipalities have in this type of system, because the water treatment systems. About the chlorination technologies, the use of sodium hypochlorite becomes interesting for security, simplicity of installation and operation. The disadvantage of using this type of system is given the possibility of formation of toxic by-products, within which you can highlight the trihalomethanes (THMs) and haloacetic acids (AHAs), but this formation can theoretically be reduced by the presence of high concentrations of ammoniacal nitrogen in effluents of these systems, for its preferential reaction with the chlorine in the formation of cloraminas. Other possibilities for reducing the training is to reduce the concentration of precursors (organic matter), reduce the dosage of chlorine and use dechlorination method after disinfection. This work, developed in PROSAB / FINEP (National Program for Research on Sanitation) research announcement number 4, developed tests for disinfection of anaerobic and facultative ponds effluents using sodium hypochlorite as a disinfectant, in concentrations of 8.0 mgCl/L and 12.0 mgCl/L. Were also developed tests for disinfection with anaerobic and facultative ponds effluents post-treated by coagulation / flocculation / sedimentation and coagulation / flocculation / flotation with dissolved air, with concentrations of 2.0 mgCl/L and 4.0 mgCl/L. For all of disinfection tests were also conducted dechlorination tests. This made it possible to study the possibilities of reducing the formation of toxic byproducts of the stabilization ponds effluents disinfection with sodium hypochlorite. The THMs and AHAS concentrations were determined by gas chromatography. Through the methods of Standard Methods 20th Edition analyses were carried out physical-chemical parameters of pH, temperature, COD, BOD, total nitrogen, ammoniacal nitrogen, total Kjeldhal nitrogen, free chlorine, chloramines, coliforms and other indicator microorganisms. The formation of THMs was very low, on average below the 20.0 µg/L in all tests, apparently due to high concentrations of NH3-N, the order of 30.0 mg/L. The same did not occur with AHAs. In many tests found concentrations of AHAs exceeded the standard of 80.0 µg/L recommended by the USEPA for drinking water. Dechlorination reduced 52% of AHAs concentrations, in average. Bioassays showed that the presence of free chlorine in the samples increase the acute toxicity in Daphnia similes. Chlorination followed by dechlorination produces effluents with less toxicity than the toxicity of chlorinated and effluent without chlorination.

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