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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
1

Adhesion of silver nanoparticle amendments to ceramic water filters

Mikelonis, Anne Marie 17 September 2015 (has links)
Silver nanoparticles (Ag NPs) are frequently added as a disinfectant to ceramic filters used for household drinking water treatment. To provide suspension phase particle stability, Ag NPs can be synthesized using a number of different molecules to cap the metal core. The goal of this doctoral work was to advance the fundamental understanding of how stabilizing agents influence the attachment and detachment of Ag NPs from ceramic water filters. To achieve this goal, deposition experiments onto Al₂O₃ membranes and clay-based ceramic filters were performed using Ag NPs stabilized by three different agents: citrate, polyvinylpyrrolidone (PVP), and branched polyethylenimine (BPEI). Laboratory and field- scale filtration experiments were also conducted to evaluate the removal of Ag NPs from ceramics under different water conditions -- the presence of hardness and natural organic matter (NOM). Citrate-stabilized Ag NPs were found to have the highest attachment densities, regardless of filter material. Differing attachment densities for the three types of Ag NPs were extensively explained using a combination of classic Derjaguin, Landau, Verwey and Overbeek (DLVO) theory, steric forces, and particle-particle interaction energy calculations. A multilevel statistical model was built to describe the removal of Ag NPs from ceramic water filters under different water conditions. The type of Ag NP was found to affect the initial release of Ag from the filters, while the interaction of the type of Ag NP and water were found to affect the rate of removal. Hardness and NOM prolonged the release of Ag from ceramic water filters.
2

Carbon Fibre Reinforcement of Ceramic Water Filters

Nicholson, Diana 18 September 2012 (has links)
This research strived to examine the potential for carbon fibre to improve the strength characteristics of ceramic water filters (CWFs) to improve their length of use in the field while maintaining, or improving, existing flow and bacteria attenuation capabilities. Model-scale CWF discs were made exploring several configurations of carbon fibre reinforcement and were tested for flow through rates, E coli attenuation, and equi-biaxial flexural strength. It was determined that, while the particular carbon fibre configurations explored in this study did not increase the strength of the CWF discs, they did provide some benefit such as improving flow-through rates while minimally detracting from bacteria removal. This indicates that the reinforcement of CWFs has potential and further research should be conducted to determine an appropriate reinforcement configuration to improve both their strength characteristics. Given that CWFs are gaining more widespread use in many countries worldwide, extending their lifespan of use would have significant value.

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