The relationship between aqueous activity coefficients (log γ(w)) and different physico-chemical properties has been studied for a number of solutes by both empirical correlations as well as by applying existing theoretical models. The solute properties selected have been classified into three categories: geometrical, polar, and electrostatic. The solutes chosen were divided into two major groups: (a) Training Set. Structurally simple compounds, i.e., each containing only one functional group, and (b) Test Set. A series of drugs and pollutants covering a wide variety of functional groups. The Training Set is in turn formed by four sub-sets of structurally related solutes, each representative of typical data sets used in the literature for solubility studies. Linear relationships were found for polar and geometric parameters in agreement with those reported in the literature. However, although the overall correlations are good, the quality of the regressions among the sub-sets is not uniform. The generality of the relationships obtained with the Training Set was tested by applying the obtained expressions to estimate log γ(w) of the solutes of the Test Set. It was found that the parameters of the theoretical models are the only ones whose relationship with log γ(w) is maintained for both the Training and the Test sets. The theoretical models used are: octanol-water partition coefficient estimated by both Rekker's (parameter LOGP) and by Leo's (parameter PCLOGP) methods; the solubility group contributions method of Wakita et al. (1986) (parameter WAKITA); the Linear Solvation Energy Relationships model (parameter KAMLET), and the UNIFAC model. The theoretical approaches were evaluated based on two criteria: accuracy of predictions and range of applicability. The accuracy of predictions was quantitated by a prediction coefficient, P², which although analogous to regression coefficient (R²) is far less flexible. Prediction coefficient is sensitive not only to scatter of the predictions but also to the systematic errors of the model being tested. The range of applicability was quantitated by the fraction (f) of solutes within the data set for which estimates by the given methodology are possible. The Accuracy-Generality Product (AGP) defined as the product of P² and f was used as the overall criterion for evaluation. The results indicated that the quality of predictions of the theoretical models as determined by the AGP is PCLOGP > LOGP > WAKITA > UNIFAC > KAMLET, for both the Training and Test sets.

Thesis (Ph.D. - Hydrology and Water Resources)--University of Arizona. / Includes bibliographical references (leaves 208-221).

No description available.

Solubility of drugs in non-aqueous systems is very important in understanding the partitioning and transport behavior. The present study was undertaken to evaluate the entropic and enthalpic contribution to activity coefficient of organic compounds (polycyclic aromatic hydrocarbons, aliphatic acids, aliphatic alcohols etc.) in non-aqueous solvents. The activity coefficient can be written as: ln γ₁ = ln γ₁ᶜ + ln γ₁ʳ where superscript "c" and "r" denote entropic (combinatorial) and enthalpic contribution respectively. We selected three solvent systems: benzene, triolein and octanol. The different models considered in this study were Flory-Huggins, Scatchard-Hildebrand, UNIQUAC combinatorial and UNIFAC residual. A combination of Flory-Huggins and Scatchard-Hildebrand which accounts for both the entropic and enthalpic effects gives the best predictions in all the solvents considered.

The work summarizes the results of a studies conducted with six different flushing agents, i.e. two anionic surfactants (SDS and DOWFAX 8390), two complexing agents (cyclodextrins), a humid acid, and an alcohol (ethanol), for solubilizing and removing residual-phase immiscible liquid from porous media. Batch experiments were conducted to measure the degree of trichloroethene (TCE) and tetrachloroethene (PCE) solubilization induced by these agents. These studies revealed that the solubility of TCE and PCE was enhanced significantly. Column experiments were conducted to compare water and agent-enhanced flushing of Borden sand containing residual saturations of TCE and PCE. The results of these studies indicate that the total flushing volume necessary to remove the contaminant was reduced substantially in the presence of all applied agents. The relative effectiveness of the agents varied based on the method of evaluation. It was shown that a volatile contaminant, e.g. toluene, TCE, and PCE, can be separated from cyclodextrin solution by mean of air-sparging. The cyclodextrin solution was successfully reused for continuos flushing of a contaminated porous material. The simulation of selected experiments revealed that the mass transfer rate coefficients are generally increasing if evaluated based on the aqueous driving force approach. However, a relation based on the enhanced driving force approach was found to be less significant. Even though areas of additional research have been identified, this research contributes to a better understanding of the processes governing chemically enhance flushing of contaminated porous media.

This dissertation examines three different aspects of groundwater contamination by immiscible liquids, both at laboratory and field scale. The first component incorporates a study of denser than water immiscible-liquid dissolution at the laboratory scale that aims to describe the effects of immiscible liquid source-zone saturation, distribution, and length on dissolution rates. It was observed that overall immiscible-liquid saturation, distribution, and source zone length did not influence initial dissolution rates under the condition of the experiments. However, transient phase dissolution behavior, primarily observed by the heterogeneously packed columns, was significantly different to that of the homogeneously packed columns. This indicates that initial dissolution rates are comparable for these different systems, however it is demonstrated that immiscible liquid distributions (e.g., heterogeneity) can significantly effect transient dissolution rates. The second component investigates the effectiveness of a field-scale partitioning tracer test (PTT) for the measurement of the amount of denser than water immiscible liquid in the subsurface. It was demonstrated that the effectiveness of partitioning tracer test may be significantly limited by factors contributing to nonideal transport such as sorption, tracer mass, and immiscible liquid distribution. The third component examines the effectiveness of a field-scale remediation technology for the enhanced removal of denser than water immiscible liquid in the subsurface. An important component of this project was the implementation of reagent recovery and reuse, which improved the efficiency of the technology. It was demonstrated that the effectiveness of enhanced solubilization technologies for groundwater remediation may be significantly limited by the distribution of immiscible liquid in the subsurface. However, the nature of cyclodextrin (enhanced-solubilization agent) makes it an attractive option for subsurface remediation of immiscible-liquid contaminants, especially for situations where mobilization is undesirable and where the use of higher-toxicity agents is not possible.

No description available.

Orientadores: Maria Alvina Krähenbühl, Reginaldo Guirardello / Dissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia Química / Made available in DSpace on 2018-08-16T22:23:44Z (GMT). No. of bitstreams: 1 Batista_MatheusMaciel_M.pdf: 1974799 bytes, checksum: cced913200b0e245fb7dc04c7338b0da (MD5) Previous issue date: 2010 / Resumo: Os parâmetros de solubilidade tridimensional definidos por Hansen são baseados em forças de dispersão entre as unidades estruturais, interações entre os grupos polares e de ligação de hidrogênio. Para compostos, tais como ésteres graxos que apresentam longas cadeias carbônicas, essa abordagem foi utilizada para obter as três coordenadas de parâmetros de solubilidade em termos de: uma parte de dispersão, uma parte polar e uma parte de ligação de hidrogênio. Está presente neste trabalho o método de contribuição de grupos proposto por Stefanis, para a estimativa dos parâmetros de solubilidade de Hansen de compostos orgânicos puros. Esse método de predição usa dois tipos característicos de grupos: grupos de primeira ordem, que descrevem a base estrutural molecular dos compostos e grupos de segunda ordem, que são baseados na teoria de conjugação e assim, melhoram a precisão das predições. Portanto esse método de contribuição de grupos garante a predição dos parâmetros de solubilidade de Hansen de uma ampla série de compostos orgânicos. Como há uma preocupação crescente em nível mundial para a proteção ambiental e de conservação dos recursos naturais não renováveis, ésteres graxos metílicos e etílicos (biodiesel) mostram grande potencial em aplicações como substitutos do diesel. Portanto, é empregada neste trabalho a metodologia utilizada por Hansen na determinação dos parâmetros de solubilidade para o caproato de etila, caprilato de etila, pelargonato de etila, laurato de etila e miristato de etila, utilizando o modelo matemático para otimização e o método de contribuição de grupos de Stefanis. O conhecimento dos parâmetros de solubilidade Hansen de ésteres etílicos graxos à temperatura ambiente pode, consequentemente, ajudar a aperfeiçoar sua aplicação como combustível ou solvente renovável e sustentável / Abstract: The three dimensional solubility parameters defined by Hansen are based on dispersion forces between structural units, interactions between the polar groups and hydrogen bonding. For compounds such as fatty esters that have long carbon chains, this approach was used to obtain the three coordinates of solubility parameters in terms of: part of dispersion, a polar part and a hydrogen bonding part. It is presented here the group contribution method proposed by Stefanis, to estimate the Hansen solubility parameters for pure organic compounds. This prediction method uses two kinds of characteristics groups: first order groups that describe the basic molecular structure of compounds and second order groups, which are based on the conjugation theory and improve the accuracy of predictions. So this group contribution method ensures the prediction of Hansen solubility parameters for a broad series of organic compounds. Because there is an increasing worldwide concern for environmental protection and for the conservation of nonrenewable natural resources, fatty acid methyl esters and fatty acid ethyl esters (biodiesel) show large potential applications as diesel substitutes. Therefore, it is used in this work the methodology for the determination of Hansen solubility parameters for ethyl caproate, ethyl caprylate, ethyl pelargonate, ethyl laurate and ethyl myristate, using the mathematical model for optimization and of group contribution Stefanis methods. Knowledge of Hansen solubility parameters of fatty acid ethyl esters at room temperature can therefore help to improve its use as a fuel or solvent renewable and sustainable / Mestrado / Desenvolvimento de Processos Químicos / Mestre em Engenharia Química