Na fabricação de aço pelo processo de aciaria elétrica há geração de vários tipos de resíduos, dentre estes, as poeiras de aciaria. Este resíduo possui como principais constituintes os elementos Fe, O e Zn, sendo considerado perigoso na maioria dos países. Além destes elementos, a presença do cloro provoca interferência deletéria na maioria dos processos de reciclagem ou incorporação do PAE em outros materiais. Por este motivo, o cloro representa um obstáculo à ampliação das possibilidades de destinação ou reciclagem destas poeiras. Este trabalho propõe uma nova tecnologia hidrometalúrgica para a redução do teor de cloro solúvel das poeiras para teores menores que 0,3% (b.s). Esta técnica..., de modo a possibilitar a aplicação de um processo especialmente desenvolvido de lixiviação aquosa, que evita a necessidade de agitação e equipamentos especiais. O principal objetivo foi reduzir o teor de cloretos das poeiras utilizando uma baixa relação sólido:líquido, em um processo de maior sustentabilidade e menor utilização de energia e recursos hídricos. Nos ensaios foram utilizadas poeiras previamente caracterizadas em seus principais elementos e provenientes de três usinas semi-integradas, cada uma com um perfil produtivo diferente e com teores de cloro médio variando de 2,01 a 5,26% (b.s). Foram testadas duas variantes principais desta nova tecnologia, em temperatura ambiente e a 60°C. Os resultados alcançados demonstraram a possibilidade de redução do teor de cloro solúvel das poeiras acima de 90%, com uma relação sólido:líquido de até 1:0,43. Também foi possível a geração de soluções concentradas de sais que atingiram até 20% em massa de concentração, em temperatura ambiente, sem necessidade de evaporação. A fácil obtenção destas soluções concentradas potencializa a aplicação e o desenvolvimento futuro de novas tecnologias para recuperação dos sais de poeiras de aciaria elétrica, principalmente sais de potássio. O material residual, com teor de cloro reduzido, possui melhor qualidade e aptidão para ser utilizado como matéria-prima em novos ou tradicionais processos de reciclagem e incorporação em outros materiais. / The Electric steelmaking generates several types of wastes, among them the electric arc furnace dust – EAFD. This residue has as main constituents the elements Fe, O and Zn, being considered dangerous in most countries. In addition to these elements, the presence of chlorine causes deleterious interference in most of recycling processes or incorporation in other materials. For this reason, chlorine represents an obstacle to increase the possibilities for disposal or recycling these dusts. This work proposes a new hydrometallurgical technology to reduce the soluble chlorine content of these dusts to lower levels than 0.3 wt% (dry basis). This technique is based on … to enable the application of a specially designed aqueous leaching process, that avoids the need for special equipment and stirring. The main objective is to reduce the chloride content of dusts using a low solid:liquid ratio in a process of greater sustainability and lower use of energy and water resources. In the tests, dusts previously characterized in main elements were used. These dusts come from three semi-integrated plants, each one with a different production profile and average chlorine content ranging from 2.01 to 5.26 wt% (dry basis). Two main variants of this new technology were tested at room temperature and 60°C. The results showed the possibility of reducing soluble chlorine content of dusts at levels above 90%, with solid:liquid ratio up to 1: 0,43. It was also possible to generate concentrated salt solutions, reaching up to 20 wt% concentration of salts, at room temperature, without evaporation. These concentrate solutions are easily obtained and potentialize the application and future development of new technologies for recovery of electric arc furnace dust salts, especially potassium salts. The residual material with low chlorine content, has better quality and suitability for use as raw material in new or traditional recycling processes and incorporation in other materials.

Para avaliar o efeito do uso oral de omeprazol em ruminantes adultos saudáveis, foram utilizados cinco ovinos machos, com dois anos de idade, hígidos e providos de cânula abomasal, que ou não receberam nada (grupo controle) ou receberam omeprazol oral em pasta, na dose de 4 mg/kg de peso vivo a cada 24 horas, durante 7 dias, em delineamento experimental de cross-over, com período de 'wash-out' de 7 dias. Diariamente os animais foram avaliados clinicamente e foram realizados o hemograma, a hemogasometria venosa; a mensuração dos eletrólitos, o perfil bioquímico, a concentração de pepsinogênio e o pH abomasal, urinário e fecal. Foi realizada, no último dia do período experimental a curva de 24 horas, com intervalo de duas horas, para o pH abomasal e o pepsinogênio sérico. Não houve efeito de tratamento para as variáveis analisadas, que permaneceram dentro do intervalo fisiológico para a espécie ovina. O uso do omeprazol na dose de 4 mg/kg de peso corporal durante sete dias, apesar de não aumentar o pH abomasal, diminuiu as concentrações de cálcio iônico e de cloro séricas / To evaluate the effect of oral omeprazole in healthy adult ruminants, five male sheep, two years old, healthy and provided with abomasal cannula, were used. Either received nothing (control group) or received oral omeprazole paste in dose of 4 mg /kg body weight every 24 hours for 7 days in experimental design of cross-over, with period of 'wash-out' of 7 days. Every day the animals were evaluated clinically and were performed the blood test, venous blood gas analysis; the measurement of electrolytes, biochemical profile, the concentration of pepsinogen and abomasal pH, urinary and fecal. It was held in last day trial period to 24 hours curve with an interval of two hours for the abomasal pH and serum pepsinogen. There was no treatment effect for the variables that remained within the physiological range for the sheep. The use of omeprazole at 4 mg / kg body weight for seven days, while not increasing the pH abomasal decreased the calcium ion concentration and serum chlorine

<p>Organic nitrogen compounds are important in environmental systems because they are prevalent in natural waters but are also components of polymers within membrane filters that are used for water treatment. In both of these cases, these compounds can be exposed to free chlorine during disinfection, which can trigger a set of reactions that can form a host of different halogenated by-products. When such by-products form during water treatment disinfection, these by-products, known as nitrogen-based disinfection by-products (N-DBPs), can be highly toxic and affect human and ecosystem health. Alternatively, when such reactions occur during membrane filtration, the organic nitrogen compounds, which are embedded within the upper layer polymer structure of the membrane filter, can degrade when free chlorine is applied. Therefore, this research was aimed at exploring the chemistry behind how specific types of organic nitrogen compounds which are found in these applications, such as tertiary amines and amides, react with free chlorine. It particularly focused on assessing the kinetics and by-product formation of these reactions under variable water quality conditions (e.g., pH, halide concentrations, and precursor doses).</p> <p> </p> <p>More specifically, in the first phase of this work, the roles of tertiary amines in enhancing disinfection by-product (DBP) formation, such as trihalomethanes (THMs) and haloacetic acids (HAAs), during chlorination of aromatic compounds were studied. The results indicated that in synthetic solutions, chloroform (CHCl₃) and trichloroacetic acid (TCAA) were enhanced by up to 20× with tertiary amines at low dose ([tertiary amine]₀ = 0.5×[aromatic compound]₀). The enhancement effect was also dependent on the aromatic compound type, tertiary amine type and dose, and water conditions such as pH and bromide concentrations. Thus, THMs and HAAs were predicted to be enhanced when the aromatic compound reacted with R₃N-X⁺ (X=Br or Cl) and was not outcompeted by aromatic compound or tertiary amine reaction with free chlorine or bromine alone. In the second phase of this work, the reaction kinetics, by-product formation, and overall mechanisms of a polyamide-based monomer with chlorine were evaluated under varying water conditions. The current known mechanism, Orton Rearrangement, was reevaluated, and new mechanisms were proposed, where it was found that N-halogenation and ring halogenation were two independent pathways. The ability to choose either pathway was highly dependent on the water quality condition of the aqueous solution. The roles of different chlorinating/brominating agents were also investigated where certain species-specific rate constants were obtained. For the N-halogenation pathway, only chlorination and no bromination occurred in which the reactivity of the chlorinating agents likely decreased such that ClO^->HOCl. However, for the ring halogenation pathway, both chlorination and bromination occurred in which the reactivity of the chlorinating and brominating agents decreased such that Cl₂ >HOCl, and BrCl > BrOCl > Br₂ > Br₂O > HOBr, respectively. Overall, this study suggests that a number of unique reactions can occur for various types of organic nitrogen compounds which: (i) allow them to affect water quality by enhancing DBP formation, (ii) but, when integrated into a polymer matrix used for water treatment, can induce reactions that lead to permanent structural damage of the polymer. In all cases, the extent of these reactions is strongly governed by the surrounding water matrix.</p>

Foi realizado estudo de desinfecção comparativo, em condições experimentais similares, entre hipoclorito de sódio, ácido peracético, ozônio e o processo de desinfecção seqüencial ozônio/cloro para águas de estudo com características de cor baixa (< 5 uH) e cor elevada (> 100 uH). O desempenho dos desinfetantes foi avaliado segundo a inativação de três microrganismos indicadores, Escherichia coli ATCC 11229, colifagos e Clostridium perfringens ATCC 13124. As concentrações aplicadas de cloro (\'CL IND.2\'), ácido peracético e ozônio (\'O IND.3\') foram de 2,0; 3,0; 4,0 e 5,0 mg/L. A desinfecção seqüencial consistiu das seguintes combinações de concentrações em mg/L: 2,0 \'O IND.3\' / 2,0 \'CL IND.2\'; 3,0 \'O IND.3\' / 2,0 \'CL IND.2\'; 5,0 \'O IND.3\' / 2,0 \'CL IND.2\' e 2,0 \'O IND.3\' / 5,0 \'CL IND.2\'. Os tempos de contato empregados foram de 5, 10, 15 e 20 minutos, tanto para os ensaios individuais, como para a etapa seqüencial. O cloro livre aplicado foi rapidamente transformado em formas de cloro combinado, nos primeiros 5 minutos de contato, para todas as dosagens aplicadas, diminuindo a ação desinfetante do mesmo. Os resultados dos ensaios de desinfecção com ácido peracético indicaram efetiva redução dos microrganismos indicadores empregados, mesmo na presença de elevada concentração de matéria orgânica, proveniente dos meios de cultura. O ozônio foi considerado efetivo para inativação dos três microrganismos indicadores, apresentando melhores resultados que os demais desinfetantes, na inativação dos fagos. Na etapa da desinfecção seqüencial as inativações de E. coli, colifagos e C. perfringens foram substancialmente superiores às inativações obtidas com ozônio e cloro individuais. Ocorreu sinergismo para E. coli e fagos para todas as dosagens e tempos de contato empregados. Em relação à bactéria esporulada C. perfringens tal fenômeno não foi observado para todos as combinações de ozônio e cloro testadas / This is the result of a comparative disinfection study, performed in similar experimental conditions, among hypochlorite of sodium, peracetic acid, ozone and the ozone/chlorine sequential disinfection process for waters of study with low color (< 5 uH) and high color (> 100 uH) features. The disinfectants performance was evaluated according to the inactivation of three indicators microorganisms: Escherichia coli ATCC 11229, coliphages and Clostridium perfringens ATCC 13124. The applied concentrations of chlorine (\'CL IND.2\'), peracetic acid and ozone (\'O IND.3\') were of 2,0; 3,0; 4,0 and 5,0 mg/L. The sequential disinfection consisted of the following concentrations combinations in mg/L: 2,0 \'O IND.3\' / 2,0 \'CL IND.2\'; 3,0 \'O IND.3\' / 2,0 \'CL IND.2\'; 5,0 \'O IND.3\' / 2,0 \'CL IND.2\' and 2,0 \'O IND.3\' / 5,0 \'CL IND.2\'. The different times of contact employed were of 5, 10, 15 and 20 minutes, as for the single test, as for the sequential stage. The free chlorine applied was quickly transformed into combined chlorine forms, in the first 5 minutes of contact, for all the dosages applied, reducing its disinfectant action. The disinfection tests results with peracetic acid indicated an effective reduction of the indicators microorganisms employed, even in the presence of a high concentration of organic matters, deriving from the culture medium. The ozone was considered effective for the inactivation of all the three indicators microorganisms, presenting better results than the other disinfectants for the phages inactivation. In the stage of the sequential disinfection, the inactivations of E. coli, coliphages and C. perfringens were remarkably superior to the inactivations obtained with just ozone and chlorine. It occurred synergism to E. coli and phages for all dosages and times of contact employed. Such a phenomenon was not observed in relation to the sporulated bacteria C. perfringens, for all the combinations of ozone and chlorine tested

A operação de uma estação de tratamento de esgotos pode apresentar várias alternativas para condução da desinfecção do efluente final, devendo-se levar em conta os seus custos, benefício, facilidade de instalação, operação, disponibilidade no mercado e as propriedades de cada agente desinfetante. Dentre os diferentes agentes desinfetantes que podem ser empregados o cloro é o que mais tem sido utilizado em função do seu baixo custo, facilidade de operação e também pelos diversos estudos realizados e consolidados com esse agente desinfetante. Desta forma, este trabalho estudou o efeito da variação da qualidade do efluente final produzido em sistemas de lodos ativados convencional no processo de desinfecção utilizando cloro na forma de hipoclorito de sódio. O efluente final empregado na condução dos ensaios experimentais foi gerado pela ETE Jesus Netto, sendo que a instalação piloto consistiu em um tanque de contato com dimensões de 3 metros de comprimento, 3 metros de largura e 0,8 m de altura útil, perfazendo um volume útil igual a 7,2 m³. A dosagem aplicada de agente oxidante foi de 5 mgCl2/L e os tempos de contato avaliados foram de 10 minutos a 30 minutos. Nos ensaios realizados houve a formação de cloraminas, provenientes da nitrificação parcial do processo de lodos ativados da ETE, e em alguns casos também foi observada a presença de cloro residual livre na saída do tanque de contato. Para ensaios de avaliação microbiológica do efluente desinfetado foram observados valores de remoção acima de 5 (expresso como log No/N) para coliformes totais para um tempo de detenção hidráulico superior a 30 minutos e remoção acima de 4 (expresso como log No/N) de coliformes termotolerantes para tempos de detenção hidráulico superior a 20 minutos. ) Para os parâmetros físico-químicos cor aparente, pH, turbidez, nitrogênio amoniacal, demanda química de oxigênio, carbono orgânico total e sólidos suspensos totais não foram observados alterações significativas no afluente e efluente do tanque de contato do processo de desinfecção. Para valores de DBO5,20 inferiores a 20 mg/L e valores de sólidos suspensos totais inferiores a 30 mg/L, não foram observados efeitos no comportamento do processo de desinfecção nos efluentes da ETE Jesus Netto. Os ensaios realizados permitiram avaliar a formação de subprodutos da desinfecção, sendo que os valores de trihalometanos no efluente da água na saída do tanque de contato resultaram abaixo de 10 µg/L. A toxicidade no efluente dos sistemas de lodos ativados convencional foi não detectável. Os bioensaios indicaram que a presença de cloro eleva a toxicidade aguda em Daphnia similis e cloração seguida de descloração produz efluentes sem toxicidade. / The operation of a Wastewater Treatment Plant (WWTP) may present several alternatives with regard to carrying out the final effluent disinfection. One must take into account cost-benefit criteria, easiness of installation and operation, availability in the disinfection market and the properties of each alternative disinfectant. Among the available disinfectant agents that can be put to use, chlorine has been the most widely utilized because of its low cost, easiness of handling and also due to the existing several studies on chlorine disinfection. In this way, this work the effects of quality variability of the final effluent from a conventional activated sludge plant (CASP) on the disinfection process with sodium hypochloride. The final effluent was generated at the Jesus Netto CASP and the pilot scale unit utilized in this work was a contact tank 3 meters long, 3 meters wide and a net depth of 0,8 meters, leading to a net volume of 7.2 m³. The applied free chlorine dose was 5 mg Cl2/L and the utilized contact times were 10 and 30 minutes. During the experimental runs there was formation of chloramines from partial nitrification in the Jesus Netto CASP. In some cases the presence of a free chlorine residual at the outlet of the contact tank was observed. Regarding microbiological evaluation of the disinfected plant effluent, removal efficiencies above 5 logs (expressed as log No/N) were observed for total coliforms with a contact time above 30 minutes and alsothermo tolerant coliform removal efficiencies above 4 logs for hydraulic residence times above 20 minutes. Regarding the physical-chemical variables apparent color, pH, turbidity, ammonia nitrogen, chemical oxygen demand, total organic carbon and total suspended solids, no significant changes in the affluent and effluent of the contact tank were observed. ) For BOD5,20 values below 20 mg/L and TSS values below 30 mg/L, no effects on the tested disinfection process for the Jesus Netto CASP were observed. The experimental runs allowed the evaluation of disinfection byproduct formation. THM levels in the contact tank effluent were below 10 µg/L. No toxicity was detected in the Jesus Netto CASP effluent. Bioassays were conducted and indicated that the presence of chlorine increased the acute toxicity level as evaluated with Daphnia similis and also that CASP effluent chlorination followed by dechlorination produced a disinfected effluent without toxicity.

Neste trabalho foram formados, sobre uma superfície de liga de alumínio AA7075-T6, revestimentos de polianilina (PANI) e da blenda polianilina/policloreto de vinila na proporção massa-massa de 1/1 (PANI/PVC 1/1), com diferentes espessuras. Os revestimentos foram avaliados quanto as suas habilidades na proteção da corrosão da liga de alumínio. Utilizou-se uma solução de NaCl 3,5%, como solução corrosiva em todos os ensaios de corrosão. A espessura dos revestimentos de PANI foi variada de 5 a 35 µm e estudou-se a relação entre espessura, rugosidade e hidrofobicidade e a proteção por estes revestimentos. Os revestimentos com espessuras de 12 a 23 µm apresentaram menor rugosidade, maior ângulo de contato e melhor proteção da corrosão verificada por medidas eletroquímicas, tais como espectroscopia de impedância eletroquímica e polarização linear. As imagens obtidas por microscopia eletrônica de varredura mostraram que os revestimentos de PANI são homogêneos e que não exibiam defeitos decorrentes da exposição no ambiente corrosivo. Já a blenda, apresentou um desempenho maior na proteção da corrosão quando comparado com a PANI pura. Medidas de espectroscopia de impedância eletroquímica e de polarização linear mostraram que a blenda possui alta resistência de polarização, com potenciais de corrosão estáveis e deslocados à região anódica para os eletrodos com revestimentos de maior espessura (26,3 &plusmn; 0,9 &micro;m). Imagens obtidas por microscopia eletrônica de varredura e de força atômica, juntamente com a análise de composição por espectroscopia de energia dispersiva de raios-X (EDX) contribuíram para entender a maior eficiência de proteção promovida pela blenda. / In this study, an aluminum alloy (AA7075-T6) was coated with polyaniline (PANI) and polyaniline/polyvinyl chloride (PANI/PVC in 1:1 ratio by mass) blend coatings of different thickness. These coatings were evaluated for their ability to protect the aluminum alloy against corrosion. For studying the corrosion of aluminum alloy in saline environment, a 3.5% NaCl solution was used in all the corrosion tests. The thickness of PANI-based films was varied between 5 to 35 µm and the effect of film thickness, roughness and hydrophobicity on the corrosion protection properties of the coatings was evaluated. The coatings with thickness between 12 and 23 µm exhibited lower roughness, higher contact angles and better corrosion protection as confirmed by electrochemical measurements such as electrochemical impedance spectroscopy and linear polarization. Morphological analysis by scanning electron microscopy confirmed that the PANI coatings are homogeneous and present almost no defects upon exposure to the corrosive environment. Compared to pure PANI coatings, the coatings consisting of PANI/PVC blend presented better performance against corrosion. Electrochemical impedance spectroscopy and linear polarization measurements showed that the blends have high polarization resistance with stable corrosion potentials that are shifted to the anodic region for the electrodes with thicker coatings (26.3 &plusmn; 0.9 &micro;m). Surface analysis by scanning electron microscopy, atomic force microscopy and elemental analysis by energy-dispersive X-ray spectroscopy were used to gather information that helped understanding the better corrosion resistance of PANI/PVC coatings.

Submitted by Sandra Pereira (srpereira@ufrrj.br) on 2017-01-20T11:19:55Z No. of bitstreams: 1 2016 - Michel Braga Garcia.pdf: 2199692 bytes, checksum: 4e890f95e489a3e9ea5a095b493dce78 (MD5) / Made available in DSpace on 2017-01-20T11:19:55Z (GMT). No. of bitstreams: 1 2016 - Michel Braga Garcia.pdf: 2199692 bytes, checksum: 4e890f95e489a3e9ea5a095b493dce78 (MD5) Previous issue date: 2016-04-06 / Coordena??o de Aperfei?oamento de Pessoal de N?vel Superior - CAPES / Studies on Atmospheric Chemistry allow the understanding of chemical behavior of different atmospheric pollutants towards oxidant agents in troposphere. Among these agents, OH radicals, ozone and nitrate radicals are the most important. In coastal zones, chlorine atoms are also important specie for the chemical removal of primary and secondary pollutants. This work aims the kinetic study of the gas phase reaction between chlorine atom and formaldehyde, H2CO + Cl ? HCO + HCl. The reaction was described at HF, MP2, CCSD, QCISD and DFT (B2PLYP, MPW2PLYP and MPWKCIS1K) levels. Basis set effect was also explored and the aug-cc-pVDZ (ACCD) and aug-cc-pVTZ (ACCT) basis set were adopted. Geometry optimizations and vibrational frequencies calculations were performed for reactants and products. A prebarrier complex was located at all levels of theory, stabilized with respect the isolated reactants by ca. 4 kcal mol-1. Saddle points were located and characterized by their imaginary frequencies. Energy barriers were predicted as ca. 1 kcal mol-1, in agreement with experimental results (0.7 ? 1.0 kcal mol-1). Rate coefficients were calculated in the range from 100 to 500 K, adopting the canonical variational method, as available in the kcvt code. The calculated kinetic parameters, rate coefficients (k, 298 K, expressed in 10-11 cm3 molecule-1 s-1), activation energy (Ea, expressed in kcal mol-1) and Arrhenius preexponential factor (A, expressed in 10-11 cm3 molecule-1 s-1) were: k = 4.89, Ea = 0.25 and A = 7.45. The results suggest that a reaction dynamics is well described by a mechanism taking into account a prebarrier intermediate. Canonical variational rate coefficients were predicted in good agreement with experimental data, validating the proposal for the reaction mechanism introduced in this study / Os estudos em Qu?mica Atmosf?rica permitem entender o comportamento qu?mico de diversos poluentes atmosf?ricos frente a agentes oxidantes presentas na troposfera. Entre esses agentes, radicais OH, oz?nio e nitrato s?o os mais importantes. Ainda em zonas costeiras, ?tomos de cloro tornam-se tamb?m importantes esp?cies para a remo??o qu?mica de poluentes prim?rios e secund?rios. Este trabalho visa o estudo cin?tico da rea??o H2CO + Cl ? HCO + HCl em fase gasosa. A rea??o foi descrita em n?veis HF, MP2, CCSD, QCISD, DFT (B2PLYP, MPW2PLYP e MPWKCIS1K) Tamb?m o efeito da base foi explorado e, para tanto, as bases aug-cc-pVDZ (ACCD) e aug-cc-pVTZ (ACCT) foram adotadas. C?lculos de otimiza??o de geometria e frequ?ncia vibracionais foram feitos para reagentes e produtos. Foram vistos tamb?m para todos os n?veis de c?lculo a forma??o de um pr?-complexo estabilizado, em rela??o aos reagentes isolados, por cerca de 4 kcal mol-1. Ponto de sela tamb?m foram otimizados e identificados pela frequ?ncia vibracional imagin?ria. Barreiras de energia foram previstas em cerca de 1 kcal mol-1, em acordo com a previs?o da literatura, 0,7 - 1,0 kcal mol-1. Os coeficientes de velocidade foram calculados na faixa de 100 ? 500 K a partir da teoria do estado de transi??o variacional com auxilio do programa kcvt. Os par?metros cin?ticos encontrados, coeficientes de velocidade (k, 298 K, expressos em 10-11 cm3mol?cula-1s-1), energia de ativa??o (Ea, expresso em kcal mol-1) e fator pr?-exponencial (A, expresso em 10-11 cm3mol?cula-1s-1) foram: k298K = 4,89, Ea = 0,25 e A = 7,45. Os resultados sugerem que a din?mica da rea??o ? bem descrita a partir de um mecanismo que contempla a participa??o de um intermedi?rio pr?-barreira. Resultados de coeficientes de velocidade variacionais can?nicos obtidos neste trabalho se mostraram satisfat?rios quando comparados a dados experimentais validando a proposta de mecanismo trazida nesse trabalho.

Due to increasingly stringent regulations, concerns about disinfection byproduct formation, and the need for improved control of distribution system water quality, there has been a shift towards the use of alternative disinfectants and oxidants in the production of drinking water. Technologies that modify water chemistry, such as hydrogen peroxide, UV irradiation, chlorine and/or chloramines may result in the generation of mineral and organic precipitates. Turbidity provides an indirect measure of the presence of particles by evaluating the light scattering properties of water. Turbidity levels are currently not monitored or regulated in treated groundwater. An important water quality parameter that influences groundwater quality is hydrogen sulfide. The control of sulfides in groundwater is of importance because its presence can cause odor and taste complaints, corrosion of pipes and other plumbing fixtures, and black-water problems in distribution systems (Levine et. al, 2004). In addition, sulfides can impose a significant oxidant demand and possibly interfere with disinfection treatments. Characteristics of particles from untreated and treated groundwater were tested as part of a field study to evaluate alternative wellhead treatment approaches for controlling hydrogen sulfide. A 1 gallon per minute (gpm) pilot-plant was used to test several groundwater treatment scenarios. The chemicals tested included chlorine, monochloramine, and hydrogen peroxide either alone or in tandem. Photochemical oxidation was evaluated using UV and advanced oxidation was evaluated using hydrogen peroxide coupled with UV. Testing was conducted either on water pumped directly from the well at ambient (7.0-7.5), or pretreated with caustic soda to evaluate the impact of elevated pH (8.2) conditions. The formation of particles was quantified using turbidity, solids (total, dissolved and suspended), and particle counts before and after oxidation. The particulate matter was characterized using a particle size analyzer in conjunction with scanning electron microscopy coupled with energy dispersive spectroscopy (SEM/EDS). Treatment systems that rely on in-line treatment lack mechanisms for particle removal, therefore particles generated through treatment are introduced into the distribution system. It is evident from this project that treatment systems should be optimized to prevent particle formation.

The photocatalytic oxidation of trichloroethylene (TCE), ethylene. ethane and toluene on TiO2, Pt/TiO2 and Ag/TiO2 were investigated in a dedicated reactor set-up operated at room temperature and ambient pressure condition. The gas phase experiments were carried out for both single and binary mixtures of these chemicals to identify the role of Pt and Ag metallisation in the photocatalytic oxidation of different contaminants. In a single contaminant system, the presence of Pt enhanced the oxidation of ethylene, ethane and toluene but detrimental to the oxidation of TCE. In the oxidation of ethylene, Pt enhanced the oxidation by acting as catalyst and as electron sink. However, in ethane oxidation, the enhancement was solely associated to the ability of Pt to act as electron sink. The detrimental effect observed in TCE oxidation was attributed to Pt and Cl interaction, which formed a persistent inorganic chlorine species decreasing the overall Pt/TiO2 photocatalyst performance. Interestingly, Ag did not show any significant effect to the oxidation of any single system degradation. In binary system degradation, where TCE and another organic compound either ethylene, ethane or toluene were degraded simultaneously, Pt always caused a detrimental effect due to its strong interaction with Cl. However, the presence of Ag and Cl gives a more synergetic effect. Ag was found to provide sites to temporarily trap chlorine radicals as AgCl. Under illumination, electrons transferred from Cl to Ag forming chlorine radicals that could react with the surface contaminant enhancing its breakdown and mineralization.

<p>Oscillator strengths and transition energies are calculated for several mono-substitutes of benzene and naphthalene molecules. The substituents investigated are chlorine, bromine and iodine. Calculations for these molecules are presented, at the Hartree-Fock and DFT level of theory. The functional used in DFT is CAM-B3LYP.</p>