In this study frequency modulation was used with a regenerative spectrometer and a super-regenerative spectrometer to detect the nuclear quadrupole resonance frequencies of chlorine in two commercially available compounds, 1, 3, 6, 8 - tetrachlorophyrene and 3, 4, 5, 6 - tetrachlorophthalimide.

Liquid phase catalytic hydrodechlorinations can provide a convenient and environmentally friendly method for treating organic chlorinated compounds in waste streams generated during the manufacturing of agrochemicals. During such treatment hydrochloric acid is generated as a by-product, which can be easily neutralized employing a base to yield an inorganic salt. This work describes the results obtained during the liquid phase hydrodechlorination of 2,6-dichlorophenol (2,6-DCP) and 2,4,6-trichlorophenol (2,4,6-TCP). The hydrodechlorination of these chlorinated phenolic compounds in a mixture of methanol and water was investigated using supported and unsupported palladium catalysts to yield lower chlorinated phenols or phenol. Various parameters were investigated such as catalyst concentration, ammonium formate concentration, effect of base addition and effect of temperature. During this study two methods of hydrodechlorination were also investigated such as hydride-transfer hydrogenolysis, using ammonium formate, and hydrogenolysis, using dihydrogen. These methods offer a mild treatment in terms of the reaction temperature with temperatures used below 800C. A comparison of the palladium catalyst systems using these methods also showed that Pd/C produced the best results in terms of the hydrodechlorination rate and the selectivity towards phenol. When the ammonium formate method was used, complete hydrodechlorination of both substrates was achieved in 1h of reaction time at a selectivity of 100 percent towards phenol. A comparison of the method using dihydrogen and Pd/C showed that the reaction rate and the selectivity towards phenol during the hydrodechlorination of 2,6-DCP were 87.92 percent and 93.30 percent. Similarly, the reaction rate and selectivity during 2,4,6- TCP hydrodechlorination were 63.77 percent and 70.57 percent. These results were achieved in a reaction time of 3 hours. A high catalyst loading increases the reaction rate at the expense of selectivity, due to the formation of cyclohexanone, formed during further hydrogenation of phenol. The formation of cyclohexanone was limited at high temperatures (ca. 800C) with none detected during the hydrodechlorination of 2,6-DCP and 0.19 percent during the hydrodechlorination of 2,4,6-TCP. Evaluation of the hydrodechlorination parameters showed that the catalytic efficiency of the Pd/C catalysts was inhibited as the reaction proceeded due to the formation of HCl as by-product. A significant increase in the reaction rate was achieved when the reaction was performed in the presence of an inorganic base, which neutralized HCl.

Orientador: Bruno Coraucci Filho / Dissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia Civil, Arquitetura e Urbanismo / Made available in DSpace on 2018-08-26T17:38:42Z (GMT). No. of bitstreams: 1 Albano_PauloVitor_M.pdf: 3074541 bytes, checksum: 6b0f67ea4023640d18132645c437f8d0 (MD5) Previous issue date: 2014 / Resumo: A cloração é a tecnologia mais aplicada dentre os diversos processos utilizados para desinfecção das águas residuárias, devido ao custo reduzido e praticidade de aplicação, quando comparada com as demais técnicas. O inconveniente do uso deste tipo de técnica é a possibilidade de formação de subprodutos de desinfecção, dentro dos quais se destaca os trialometanos (TAMs). O presente trabalho avaliou a formação de TAMs em esgoto tratado de uma lagoa facultativa, submetido a um sistema de desinfecção por meio da utilização de ATCI. Avaliou também a eficiência deste sistema na desinfecção do efluente da lagoa facultativa. A avaliação consistiu de ensaio experimental, realizado em laboratório, para definição da dosagem e do tempo de contato; além do teste em escala real com a implantação do sistema de desinfecção na lagoa facultativa, situada no município de Itirapuã - SP. Os resultados obtidos demonstram que o sistema foi efetivo na desinfecção do efluente com uma aplicação de 10mg/L de cloro residual total e sem formação significativa de TAM, em média abaixo dos 3,0 µg/L, aparentemente devido à presença de concentrações elevadas de nitrogênio amoniacal (N-NH3) no efluente, da ordem de 43,0 mg/L. Conclui-se que a utilização do ATCI torna-se interessante devido à segurança, simplicidade das instalações e facilidade operacional / Abstract: Chlorination is the most technology applied among the different processes used for disinfection of wastewater, due to reduced cost and practicality of application compared with other techniques. The disadvantage of using this type of technique is the possibility of formation of disinfection byproducts within which stands trihalomethanes (TAMs). This study evaluated the formation of TAMs in treated sewage from a facultative pond, subjected to a disinfection system through the use of ATCI. Also evaluated the efficiency of this system for the disinfection of effluent from facultative pond. The evaluation consisted of an experimental test performed in the laboratory, to define the dosage and time of contact; beyond the full-scale test with the implementation of the disinfection system in the facultative pond, located in the municipality of Itirapuã - SP. The results demonstrated that the system was effective in disinfection of the effluent with an application of 10 mg / L of total chlorine residual and without significant formation of TAM on average below 3.0 g / L, apparently due to the presence of high concentrations of ammonia nitrogen (NH3-N) in the effluent of the order of 43.0 mg / L. We conclude that the use of ATCI becomes interesting due to security, simplicity of installation and operational ease / Mestrado / Saneamento e Ambiente / Mestre em Engenharia Civil

Previous research by Rushing et al. (2002) identified key factors contributing to the formation of pinhole leaks in copper plumbing. These factors included high chlorine, pH levels and the presence of aluminum solids. Experiments were conducted to 1) examine the interplay between these constituents, 2) confirm that the water was aggressive enough to eat a hole through a pipe, 3) examine phosphate inhibition, and 4) try to determine the scope of this pitting problem in other distribution systems and on a national level. The first set of experiments clearly defined the controversial trends from earlier work. At certain pH values, the presence of chlorine and aluminum solids does seem to initiate pitting corrosion of copper. Although the problem is most severe at higher pH, it is likely that long-term exposure at lower values such as pH 8 could lead to pitting. There is a concentration effect of aluminum solids at pH 9.0, in that higher concentrations cause an earlier rise in the potential for copper to corrode if sufficient chlorine is present. The second phase of experiments are the first to prove that a potable water containing aluminum, high chlorine residual, and relatively high pH can cause pinholes in copper tube. To our knowledge this is the first time the phenomenon of pinhole leaks has been reproduced in the laboratory as it occurs in the field. It therefore proves that "aggressive water" alone can cause the problem of pitting. The role of flow, pipe orientation and hypothesized surface defects was directly examined as part of this evaluation. Pitting increased with greater water usage and for sections of straight pipe exposed to hydraulic conditions near bends. Copper pipe sections polished to a mirror like finish to remove surface defects were also severely attacked. The role of phosphate in mitigation of copper pitting corrosion was defined in a subsequent experiment using synthesized water. Phosphates did not have an effect at pH 7.7 and were found to reduce electrochemical indications of pitting in the synthetic water at the pH of 8.3. Phosphates had lesser benefits at higher pH even in synthetic water, but overall, even at pHs as high as 10, some benefits from orthophosphate dosing might be anticipated. Effects of orthophosphate on the inhibition of copper pitting corrosion were then applied to treated water from a utility in Washington D.C., whose consumers have experienced an outbreak of pinhole leaks in household copper plumbing. After comparing electrochemical results from synthetic and actual water from the treatment plant, there was evidence of a natural inhibitor to pitting corrosion in WSSC water that is not present in the synthetic water. The higher chloride concentration in the water after ferric chloride was dosed at the treatment plant may have reduced the pitting propensity of the water. The effects of phosphates seemed to reduce the pitting propensity of real water at pH 8.3 although little benefit was seen at pH 9.1. These defined characteristics of copper pitting were then applied in a systematic evaluation of a water utility experiencing pitting corrosion in Roanoke, VA. This case study further supported the hypothesis that high levels of aluminum, chlorine, and pH may be combining to catalyze copper pitting in practice. Recommendations to alter the treatment strategies at these utilities were proposed to help mitigate the pitting corrosion problems in these areas. A national survey then confirmed pitting is occurring at a significant frequency at other large utilities across the U.S. / Master of Science

Listeria monocytogenes response to oxidative stress by sublethal sodium hypochlorite was investigated in this study. Continuous exposure of sublethal chlorine influenced biofilm formation and stress adaptation (homologous and heterologous) in L. monocytogenes. The biofilm forming ability of oxidative stress adapted and control cells were investigated on polystyrene surface at 22°C and 37°C. The oxidative stress adapted cells were found to form less biofilm in the presence of chlorine (p < 0.10) when compared to non-treated control cells at both the temperatures. In addition, the biofilm forming ability of L. monocytogenes was reduced significantly at higher sublethal chlorine concentrations (p < 0.10). In conclusion, oxidative stress adapted L. monocytogenes has developed tolerance to chlorine and some of the antibiotics. However, oxidative stress those cells did demonstrate an antibiofilm effect. This demonstrates that oxidative stress reduces L. monocytogenes biofilm formation but can also increase antibiotic resistance.

No description available.

Chlorine is used as a powerful disinfectant in water-related industries and in the food industry to remove bacteria and other harmful contaminants. We present a solution-based fabrication process for a biodegradable electrochemical free chlorine sensor using asparagine that is functionalized onto graphene oxide (GO). An ink solution of the GO functionalized with asparagine was fabricated then deposited onto a screen-printed carbon electrode (SPCE) using a spin-coater. The sensor showed high a sensitivity of 0.30 μA ppm−1 over a linear range of 0 to 8 ppm with a hysteresis-limited resolution of 0.2 ppm, very high selectivity in the presence of commonly interfering ions, and an operating voltage well below the reduction potential of dissolved oxygen. The sensor response time to achieve a steady state was 50 s, and it showed little change in its drift response over 16 h and over a temperature range of 10 to 45 °C. From the development of the free chlorine sensor, over 9000 datapoints were collected and used for training a neural network model to quantify and characterize factors affecting the free chlorine sensor performance. A readout system was designed with a printed circuit board and an android app to simplify free chlorine sensing for an end user. / Thesis / Master of Applied Science (MASc) / Free chlorine is used to disinfectant sources of water, and eliminate pathogens. The World Health Organization (WHO) maintains strict amounts of free chlorine in water due to its widespread usage owed to its low cost and persistence in water systems. Too little, and it will not be an effective disinfectant, and too much and the high consumption of free chlorine increases the risk cancer or the formation of hazardous chemicals. Recently, free chlorine sensors that measure an electrical response proportional to the amount of free chlorine are gaining interest for fast, accurate, and repeatable measurements. This thesis focuses on the design, fabrication, and evaluation of these sensors made using biodegradable materials in a solution-based fabrication processes with the aim of working towards large-scale fabrication of a printable ink. First, we review the results achieved by the sensors within recent literature. Second, we present the design of a sensor that aims to achieve environmentally friendly goals and maintain competitive performance characteristics. The, the sensor is tested under various conditions with its performance quantified under different conditions. Third, the sensor is characterized using a neural network to measure its performance and identify sources of improvement for future designs. Finally, we incorporate the sensor with an android app to measure free chlorine in remote water systems.

B.S.

<p> A brief review of the rhenium-chlorine system is presented and a method to determine rhenium:chlorine atom ratios by neutron activation analysis is described. An infrared cell which is useful for highly re-active vapours at temperatures up to 400°C is also described. The compound claimed to be rhenium hexachloride is shown to be rhenium oxytetrachloride and a reliable preparation of β-rhenium tetrachloride is discovered. The hexachlororhenate(V)ion and several complexes containing rhenium(V), rhenium(VI) and rhenium(VII) are prepared. Chemical and physical evidence is used to predict structures of some of the above compounds.</p> / Thesis / Doctor of Philosophy (PhD)

Microbial recovery methods for frozen blueberries, and postharvest sanitation treatments on microbial load and sensory attributes of berries were studied. Previously frozen rabbiteye blueberries were subjected to hand-mixing, machine-mixing, stomaching, vortexing, and homogenization. Aerobic (APC) and yeast and mold (YMC) counts did not differ amongst treatments but homogenization, stomaching, and vortexing tended to yield a higher recovery, with vortexing resulting in the choice method for YMC possibly due to cell disruption and colony breakage. Fresh highbush blueberries were treated with hot water (60 - 90°C) with an oxidizing agent (0 - 0.1% Boxyl®) for 10 – 30s. Water temperature was the most influential (p<0.05) factor on microbial reduction, wax/bloom and color. Holding berries at 75°C for 20s (without antimicrobial) or dipping in 200ppm chlorine for 10s resulted in 0.90 and 1.80 log reduction of APC and yeast, respectively; and 0.80 (200ppm/10s) and 2.90 (75°C/20s hot water) log reduction in mold counts.