Award Date

1-1-2008

Degree Type

Dissertation

Degree Name

Doctor of Philosophy (PhD)

Department

Mechanical Engineering

First Committee Member

Shizhi Qian

Number of Pages

124

Abstract

Mercury and many radionuclides are extremely toxic, and their monitoring and detection are of importance for human health and environmental protection. This dissertation focuses on the detection of mercury (II) ions and radionuclides including uranium (234U and 238U), plutonium (239Pu), and americium (241Am) in aqueous solutions under the effects of electromagnetic fields. The stripping electrochemical method has been widely used to detect mercury (II) ions in aqueous solutions. To enhance the detection sensitivity of the conventional electrochemical method, mechanically stirring the solution is usually performed to enhance the rate of the ionic mass transport. Instead of mechanically stirring the solution; the electrochemical cell is positioned in a magnetic field provided by permanent magnets. The interaction between the current density transmitted through the solution and the magnetic field induces Lorentz force, thus magneto-hydrodynamic (MHD) flow, which can be used to stir and mix the sample solution uniformly without the use of any mechanical moving parts or rotating electrodes; This research develops an ultra sensitive mercury sensor by integrating the MHD with the electrochemical analyzer, and with the surface plasmon resonance (SPR) instrument, and its detection limit is obtained down to 1 ppb. To improve the resolution of the alpha spectrum during the detection of 234U, 238U, 239Pu, and 241Am, hydrous oxides of the radionuclides were electrochemically deposited onto the surface of a steel planchet in the presence of a magnetic field. The steel planchet was then washed and dried, and the energy spectrum emitted was measured with the alpha spectrometer. A homogeneous and thin film with larger grain size was formed during the deposition step due to the induced MHD flow leading to a higher resolution in the detection sensitivity and the alpha spectrum.

Keywords

Detection; Effects; Electromagnetic; Electromagnetic Fields; Fields; Mercury; Radionuclides

Controlled Subject

Mechanical engineering; Biomedical engineering

File Format

pdf

File Size

3143.68 KB

Degree Grantor

University of Nevada, Las Vegas

Language

English

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