No / We describe the Δlog P method for the assessment of intramolecular hydrogen bonds (IMHBs), and show that it is not a very general method of distinguishing between molecules in which there is an IMHB and molecules in which there is no IMHB. The ‘double’ Δlog P method of Shalaeva et al. is a much more reliable method for the assessment of IMHB but requires the synthesis of a model compound and the determination of no less than four water-solvent partition coefficients. In addition, it is difficult to apply to compounds that contain more than one hydrogen bond acidic group capable of IMHB. We then describe our NMR method of assessing IMHB, based on 1H NMR chemical shifts in solvents DMSO and CDCl3. We have determined 1H NMR chemical shifts for a number of ortho-substituted anilines and show that the only compound we have studied that forms an IMHB is methyl 2-methylaminobenzoate though there is no IMHB present in methyl 2-aminobenzoate. This apparently anomalous result is supported by both MM and ab initio calculations. The NMR method is much simpler and less time consuming than other methods for the assessment of IMHB. It provides a quantitative assessment of IMHB and can be applied to molecules with more than one hydrogen bond acidic group.

Yes / We describe the Δlog P method for the assessment of intramolecular hydrogen bonds (IMHBs), and show that it is not a very general method of distinguishing between molecules in which there is an IMHB and molecules in which there is no IMHB. The ‘double’ Δlog P method of Shalaeva et al. is a much more reliable method for the assessment of IMHB but requires the synthesis of a model compound and the determination of no less than four water-solvent partition coefficients. In addition, it is difficult to apply to compounds that contain more than one hydrogen bond acidic group capable of IMHB. We then describe our NMR method of assessing IMHB, based on 1H NMR chemical shifts in solvents DMSO and CDCl3. We have determined 1H NMR chemical shifts for a number of ortho-substituted anilines and show that the only compound we have studied that forms an IMHB is methyl 2-methylaminobenzoate though there is no IMHB present in methyl 2-aminobenzoate. This apparently anomalous result is supported by both MM and ab initio calculations. The NMR method is much simpler and less time consuming than other methods for the assessment of IMHB. It provides a quantitative assessment of IMHB and can be applied to molecules with more than one hydrogen bond acidic group.

Uma das propriedades fundamentais de soluções de micelas aquosas é sua capacidade de solubililizar uma ampla faixa de solutos orgânicos com diferentes graus de polaridade e hidrofobicidade. Recentemente Quina et. aI., estudaram as interações químicas específicas que governam a solubilidade para um ampla faixa de solutos orgânicos em micelas usando relações lineares de energia livre de solvatação (LSERs), baseado nos parâmetros empíricos do soluto desenvolvido por Abraham. O presente trabalho trata a solubilização de solutos orgânicos em micelas baseado em parâmetros obtidos unicamente da estrutura molecular do soluto através de cálculos de química quântica. Nossos resultados mostram que valores experimentais de Ks para solubilização de solutos orgânicos em detergentes aniônicos (micelas de SDS, dodecil sulfato de sódio e agregados de SDS com PEG-polietilenoglicol) podem ser reproduzidos usando parâmetros teóricos. A relação linear teórica de energia livre de solvatação resultante é quimicamente condizente com LSERs baseados em parâmetros empíricos do soluto. No caso de detergentes catiônicos e não iônicos, a metodologia apresenta limitações, por que o método de cálculo de cargas formais usando a definição de análise populacional de Mulliken não descreve de maneira apropriada o caráter ácido e básico das pontes de hidrogênio entre os solutos e a água. Alternativas para resolver o problema da limitação imposta pelos parâmetros teóricos, mantendo a aproximação linear de energia livre, são discutidas. / One of the most fundamental properties of aqueous micelar solutions is their ability to solubilize a wide variety of organic solutes with quite distinct polarities and degree of hydrophobicity. Recently Quina et al., studied the specific chemical interactions governing the solubilities of a wide range of solutes in micelles using linear solvation energy relationships (LSERs) based on empirical solute parameters developed by Abraham. This work reports an investigation of the solubilization of organic solutes in micelles based on the use of theoretical solute parameters derived from quantum chemical calculations Our results show that the experimental Ks values for solubilization of organic solutes in anionic detergents (micelles of SDS-sodium dodecyl sulfate and aggregate formed between SDS and PEG-poly(ethylene glycol)) can be reproduced using theoretical parameters. The resultant theoretical linear solvation energy relationships are chemically consistent with LSERs based on empirical solute parameters. In the case of cationic and nonionic detergents, the theoretical parameters used to describe hydrogen bonding fail because methods of calculating formal charges using the concept of Mulliken populational analysis cannot describe hydrogen bonding donor and acceptor character in an appropriate way. Possible strategies to solve the theoretical descriptor problem in the context of the linear free energy approximation are discussed.

This thesis describes the development of a generic model for predicting the emissions of organic compounds from materials used in the manufacture of various goods and products. Many products contain organic substances that are not bound to the matrix formed by their constituent materials and are thus able to dissociate from the material and become transferred into the surrounding environment. A wide range of materials and products are used in modern societies, and many compounds deriving from these materials are regarded as emerging pollutants in both indoor and outdoor environments. The model uses three components to describe the transfer of compounds from materials to the surrounding environment: partitioning of the compound between the material and its surroundings based on linear free energy relationships, diffusion within the material based on the Piringer equation, and convective mass transfer in air or water based on an empirical flat surface model. The model’s predictive capacity was tested against three experimental case studies: emissions of plasticizers from vinyl flooring and triphenyl phosphate from LCD screens into the air, and leaching of organophosphates from concrete into water. The rates of emission from vinyl flooring were clearly affected by the number of layers comprising the material. Triphenyl phosphate was found in the front surface of all tested flat screens and its rates of emission were related to the nature of the screen and its operating temperature. The model accurately predicted emissions into the air and leaching from concrete into water once modified to include modules that describe dissolution from surfaces and diffusion in water-filled pores. The model was then used to investigate emissions on the national scale. It was found that the rates of emission from vinyl flooring are not changing over time, and that the total mass of emitted material is dependent on annual sales volumes and the expected life span of the vinyl flooring. Moreover, the additive used has a large effect on the emitted mass. Emissions from flat screen displays depend strongly on their operating temperatures: displays with high working temperatures that are active for extended periods of time produce more emissions. The model was also used to study the release of organophosphates from the concrete used to make a bridge, which depended on the flow of water under the bridge, the temperature, the porosity of the concrete, and the additive’s water solubility. Data on annual sales volumes and the total surface area of sold goods are essential when studying emissions on a national scale. National retailers’ organizations are valuable sources of such information. When adequate data are not available, it is necessary to perform uncertainty analyses to determine the impact of uncertainty in the modeling of different stages of the emissions process in different scenarios.

Emerging contaminants are defined as synthetic or naturally occurring chemicals or microorganisms that are not currently regulated but have the potential to enter the environment and cause adverse ecological and/or human health effects. With recent development in analytical techniques, emerging contaminants have been detected in wastewater, source water, and finished drinking water. These environmental occurrence data have raised public concern about the fate and ecological impacts of such compounds. Concerns regarding emerging contaminants and the many chemicals that are in use or production necessitate a task to assess their potential health effects and removal efficiency during water treatment. Advanced oxidation processes (AOPs) are attractive and promising technologies for emerging contaminant control due to its capability of mineralizing organic compound via reactions with highly active hydroxyl radicals. However, the nonselective reactivity of hydroxyl radicals and the radical chain reactions make AOPs mechanistically complex processes. In addition, the diversity and complexity of the structure of a large number of emerging contaminants make it difficult and expensive to study the degradation pathways of each contaminant and the fate of the intermediates and byproducts. The intermediates and byproducts that are produced may pose potential effects to human and aquatic ecosystems. Consequently, there is a need to develop first-principle based mechanistic models that can enumerate reaction pathway, calculate concentrations of the byproducts, and estimate their human effects for both water treatment and reuse practices. This dissertation develops methods to predict reaction rate constants for elementary reactions that are identified by a previously developed computer-based reaction pathway generator. Many intermediates and byproducts that are experimentally identified for HO* induced reactions with emerging contaminants include common lower molecular weight organic compounds on the basis of several carbons. These lower carbon intermediates and byproducts also react with HO* at relatively smaller reaction rate constants (i.e., k < 109 M-1s-1) and may significantly affect overall performance of AOPs. In addition, the structures of emerging contaminants with various functional groups are too complicated to model. As a consequence, the rate constant predictors are established based on the conventional organic compounds as an initial approch. A group contribution method (GCM) predicts the aqueous phase hydroxyl radical reaction rate constants for compounds with a wide range of functional groups. The GCM is a first comprehensive tool to predict aqueous phase hydroxyl radical reaction rate constants for reactions that include hydrogen-atom abstraction from a C-H bond and/or a O-H bond by hydroxyl radical, hydroxyl radical addition to a C=C unsaturated bond in alkenes and aromatic compounds, and hydroxyl radical interaction with sulfur-, nitrogen-, or phosphorus-atom-containing compounds. The GCM shows predictability; factor of difference of 2 from literature-reported experimental values. The GCM successfully predicts the hydroxyl radical reaction rate constants for a limited number of emerging contaminants. Linear free energy relationships (LFERs) bridge a kinetic property with a thermochemical property. The LFERs is a new proof-of-concept approach for Ab initio reaction rate constants predictors. The kinetic property represents literature-reported and our experimentally obtained hydroxyl radical reaction rate constants for neutral and ionized compounds. The thermochemical property represents quantum mechanically calculated aqueous phase free energy of activation. Various Ab initio quantum mechanical methods and solvation models are explored to calculate the aqueous phase free energy of activation of reactantas and transition states. The quantum mechanically calculcated aqueous phase free energies of activation are within the acceptable range when compared to those that are obtained from the experiments. These approaches may be applied to other reaction mechanisms to establish a library of rate constant predictions for the mechanistic modeling of AOPs. The predicted kinetic information enables one to identify important pathways of AOP mechanisms that are initiated by hydroxyl radical, and can be used to calculate concentration profiles of parent compounds, intermediates and byproducts. The mechanistic model guides the design of experiments that are used to examine the reaction mechanisms of important intermediates and byproducts and the application of AOPs to real fields.

Uma das propriedades fundamentais de soluções de micelas aquosas é sua capacidade de solubililizar uma ampla faixa de solutos orgânicos com diferentes graus de polaridade e hidrofobicidade. Recentemente Quina et. aI., estudaram as interações químicas específicas que governam a solubilidade para um ampla faixa de solutos orgânicos em micelas usando relações lineares de energia livre de solvatação (LSERs), baseado nos parâmetros empíricos do soluto desenvolvido por Abraham. O presente trabalho trata a solubilização de solutos orgânicos em micelas baseado em parâmetros obtidos unicamente da estrutura molecular do soluto através de cálculos de química quântica. Nossos resultados mostram que valores experimentais de Ks para solubilização de solutos orgânicos em detergentes aniônicos (micelas de SDS, dodecil sulfato de sódio e agregados de SDS com PEG-polietilenoglicol) podem ser reproduzidos usando parâmetros teóricos. A relação linear teórica de energia livre de solvatação resultante é quimicamente condizente com LSERs baseados em parâmetros empíricos do soluto. No caso de detergentes catiônicos e não iônicos, a metodologia apresenta limitações, por que o método de cálculo de cargas formais usando a definição de análise populacional de Mulliken não descreve de maneira apropriada o caráter ácido e básico das pontes de hidrogênio entre os solutos e a água. Alternativas para resolver o problema da limitação imposta pelos parâmetros teóricos, mantendo a aproximação linear de energia livre, são discutidas. / One of the most fundamental properties of aqueous micelar solutions is their ability to solubilize a wide variety of organic solutes with quite distinct polarities and degree of hydrophobicity. Recently Quina et al., studied the specific chemical interactions governing the solubilities of a wide range of solutes in micelles using linear solvation energy relationships (LSERs) based on empirical solute parameters developed by Abraham. This work reports an investigation of the solubilization of organic solutes in micelles based on the use of theoretical solute parameters derived from quantum chemical calculations Our results show that the experimental Ks values for solubilization of organic solutes in anionic detergents (micelles of SDS-sodium dodecyl sulfate and aggregate formed between SDS and PEG-poly(ethylene glycol)) can be reproduced using theoretical parameters. The resultant theoretical linear solvation energy relationships are chemically consistent with LSERs based on empirical solute parameters. In the case of cationic and nonionic detergents, the theoretical parameters used to describe hydrogen bonding fail because methods of calculating formal charges using the concept of Mulliken populational analysis cannot describe hydrogen bonding donor and acceptor character in an appropriate way. Possible strategies to solve the theoretical descriptor problem in the context of the linear free energy approximation are discussed.

L'objectif de cette thèse fut de développer un process pour la production d'acide peroxycarbolique à partir du peroxyde d'hydrogène et d'un acide carboxylique dans un réacteur continu. Dans un premier temps, la stabilité des espèces peroxydées fut étudiée en utilisant une méthode d'analyse en direct (spectromètre de masse). Un effort particulier a été apporté pour trouver un catalyseur hétérogène ne provoquant pas la décomposition des espèces peroxydées et ayant une activité catalytique similaire à l'acide sulfurique. Un réacteur en continu en lit fixe a été construit en utilisant des résines échangeuses de cation. / The purpose of this thesis was to find a way to produce peroxycarboxylic acid from hydrogen peroxide and carboylic acid in a continuous reactor by using heterogeneous catalysts. In the first step the stability of peroxyde species xas studied by using an online analytic method (Mass spectrometer). One of the main challenge was to find a suitable solid acid catalyst, wich does no decompose the peroxyde species and can catalyze the reaction as sulfuric acid. A continuous fixed bed reactor was built by using caion exchange resins as a catalyst.

In-stream aquatic habitat depends on adequate levels of dissolved oxygen. Human alteration of the landscape has an extensive influence on the biogeochemical processes that drive oxygen cycling in streams. Historic datasets allow researchers to track trends in chemical parameters concomitant with urbanization, while land cover change analysis allows researchers to identify linkages between water quality trends and landscape change. Using the Seasonal Kendall's test, I examined water quality trends in oxygen demand variables during the mid-1990s to 2003, for twelve sites in the Rock Creek sub-watershed of the Tualatin River, northwest Oregon. Significant trends occurred in each parameter. Dissolved oxygen (DO (%sat)) increased at five sites. Chemical oxygen demand (COD) decreased at seven sites. Total Kjeldahl nitrogen (TKN) decreased at five sites and increased at one site. Ammonium (NH3-N) decreased at one site and increased at one site. Multiple linear regression indicates that nitrogenous oxygen demand accounts for a significant amount of variance in COD at ten of the twelve sites (adjusted R2values from 0.14 to 0.73). Aerial photo interpretation revealed significant land cover change in agricultural land cover (-8% for the entire basin area) and residential land cover (+10% for the entire basin area). Correlation results between seasonal oxygen demand data and land cover values at multiple scales indicated that: (I) forest cover negatively influences COD at the full sub-basin scale and positively influences NH3-N at local scales, (2) residential land cover positively influences DO (%sat) values at local scales, (3) agricultural land cover does not influence oxygen demand at any land cover assessment scale, ( 4) local topography negatively influences TKN and NH3-N, and (5) urban runoff management infrastructure correlates positively with COD. Study results indicate that, with the exception of forested land, local scale land cover and landscape variables dominate influence on oxygen demand in the Rock Creek basin. Since DO conditions have improved in these streams, watershed management efforts should emphasize local influences in order to continue to maintain stream health.

No description available.

Priority organic and emerging contaminants are a growing concern for drinking water treatment due to their increasing presence in the environment. This study developed a predictive model for the sorption of anionic organic contaminants from drinking water on three anion exchange resins: a strong polystyrenic (IRA-910), weak polystyrenic (IRA-96), and a strong polacrylic (A860). The model quantifies the individual mechanisms of sorption using poly-parameter linear free energy relationships (pp-LFERs) and the feasibility of phase conversion (e.g., an ideal gas phase as the reference state) for ionic species was examined. To develop the model, a training set of isotherms was obtained using aliphatic and aromatic carboxylates, phenols, anilines, nitrobenzene, and ibuprofen. These compounds were chosen as model organic contaminants in the environment. The training set and 1-3 test compounds (3-methyl-2-nitrobenzoate, phenol, and 4-nitroaniline) were accurately predicted using the created model for each resin. An understanding of the effects of resin structure on sorption interactions was also developed that focused on ionic functional groups, resin matrix, and hydrophilicity (i.e. water content). It was shown that greater sorption efficiency was achieved when electrostatic (ion exchange) and nonelectrostatic (adsorption) interactions were present together to create a synergistic addition. However, sorption on ion exchangers was poor if the pH of the system approached levels lower than the sorbate pKa. Additionally, weak base exchanges lose exchange capacity as pH levels approach resin pKa (IRA-96 pKa = 6.0). Additional contributions to the sorption mechanisms were observed by studying various electron donating/withdrawing functional groups on the contaminants. It was concluded that &#960;-&#960; and H-bonding interactions contributed a greater amount to the nonelectrostatic mechanisms than cavity formation forces and nonspecific forces. A comparison between the three resins showed that IRA-96 (weak base polystyrenic) had a greater removal capacity than IRA-910 (strong base polystyrenic), followed far behind by A860 (strong base polyacrylate). This is due to differences between the resins, such as the hydrophilicity, the density of the ion exchange group, and the presence of aromatic rings within the matrix structure. Although the modeling method accurately predicted the phase change from aqueous to sorbent phases, it was shown that the SPARC calculated aqueous-gas ion transfer energies were poor estimations of the transfer energy to the ideal gas phase and further study is necessary to accurately determine this value. This modeling methodology is believed to be applicable to emerging contaminants such as pharmaceuticals in water systems and helps further new water treatment technologies while developing a mechanistic understanding of electrostatic and nonelectrostatic interactions in general. This can be applied to additional separation processes such as chemical purification and chromatographic separation. / Civil Engineering