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" Transport of Organic Compounds Through Piping Materials "
Hosseini Ghasemabadian, Payam
Abolhasani, Milad
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Latin Dissertation
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| Language of Document
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English
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| Record Number
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1058117
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| Doc. No
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TL57234
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| Main Entry
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Hosseini Ghasemabadian, Payam
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| Title & Author
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Transport of Organic Compounds Through Piping Materials\ Hosseini Ghasemabadian, PayamAbolhasani, Milad
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| College
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North Carolina State University
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| Date
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2020
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| Degree
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Ph.D.
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2020
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| Note
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144 p.
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| Abstract
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Piping materials such as pipes and rubber gaskets are an integral component of water and wastewater conveyance system. They may be subject to contamination exposure during their service life especially when located in the areas with contaminated soil and/or groundwater. Depending on the type of contamination they are exposed to, a range of species can come in contact with the outer surface of pipe or gasket and penetrate such materials leading to long-term durability issues and contamination of water flowing through the pipe. A large number of water contamination incidents reported in the US have been caused by gross spillage of gasoline or leakage from underground storage tanks in the gas stations or improper release of chlorinated solvents mainly used in dry cleaning operations resulting in the prevalence of petroleum-based products and chlorinated organic solvents in the contaminated areas. In the first part of this work, rigid PVC (u-PVC) pipe was selected based on its higher resistance to aromatic and chlorinated hydrocarbons than other types of polymer-based pipe materials. Also, three types of gaskets i.e. chloroprene rubber (CR), nitrile rubber (NBR), and fluoroelastomer rubber (FKM) were chosen to study their degradation in the presence of benzene and tertrachloroethylene (PCE). Second part is concerned with the measurement and modeling of the diffusion of (liquid) benzene and PCE in saturated cement paste while the third part of the work is on the quantification of benzene and PCE vapors transport in unsaturated cement paste. The results of the first part indicate that Williams-Landel-Ferry (WLF) method was successful in estimating the degradation of PVC pipe and rubber gaskets; a modification was made to consider the effect of contamination level of water with respect to benzene or PCE. It was also shown that FKM performed the least mechanical properties degradation followed by NBR and CR gaskets. Also, severe swelling of CR once exposed to benzene demonstrates that volume stability of gasket materials is another important factor needs to be taken into account as it may cause water leakage due to the displacement at pipeline joints leading to further contamination of the water inside the pipe. In the second part, the results reveal that the effective diffusivity (De) of VOCs in saturated cement paste decreases as water to cement ratio (w/c) decreases because of the reduced porosity and increased tortuosity of the pore network as well as increased ionic strength of the pore solution. Increasing the ionic strength of the pore solution lowers the solubility limit of VOCs in the pore solution and decreases the free diffusion coefficient of VOCs in the pore solution. Also, among the models employed to estimate De of benzene and PCE in saturated cement paste, modified Archie’s model and phenomenological models can predict the effective diffusivity of VOCs with high accuracy. Finally, the results of third part show that De of VOCs in unsaturated cement paste is significantly affected by the relative humidity (RH) of the environment the cement-based materials are exposed to; the effect of RH on reducing transport rate is larger than that of w/c ratio and VOCs size. In addition, the effect of VOCs’ size on their effective diffusivity in unsaturated cement paste became more pronounced as RH drops. Also, by further modification of commonly used composite models (parallel and serial) based on a conceptual model of cement-based matrices, an alternative composite (AC) model was proposed to better predict the values of De of benzene and PCE in unsaturated cement paste samples as compared to the parallel and series models. The modified form of Archie’s model for unsaturated porous media was shown to best predict De than other widely utilized empirical models.
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| Descriptor
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Hydrologic sciences
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Soil sciences
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Water resources management
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| Added Entry
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Abolhasani, Milad
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North Carolina State University
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