| Summary: | 博士 === 國立中興大學 === 材料科學與工程學系所 === 100 === Due to excellent properties such as excellent vibration damping property, high specific strength and EMI (electromagnetic interference), in transportation vehicle (e.g., engineering covering, oil pan, door frame wheel, etc) and the outer shell of 3C electric products (e.g., the outer covering of personal mobile communication tool, the upper cover and base seat of notebook computer, etc.), magnesium alloys has an increasing number of uses. Recycling of magnesium scraps (i.e., end-of-life or post-consumed magnesium products) has become increasingly important. The study proposes a method for generating hydrogen gas in citric acid-added seawater by the hydrolysis of magnesium scraps.
The study systematically investigates a catalyst-free method of producing hydrogen using low-grade magnesium scraps (LGMS) in aqueous organic acids. The stainless steel (S.S) net, functions as a catalyst of hydrogen production for LGMS plate in seawater, obviously improve the hydrogen yield, but losing the function of catalyst in citric acid-added seawater. The hydrogen yield was highest when the concentration of citric acid is at 30 wt%, while magnesium plate was placed in citric acid-added seawater. Activation energy for the H2 generation in citric acid-added seawater was calculated. The mobility and concentration of hydrogen ions in citric acid aqueous affect the total hydrogen yield, causing that the highest yield occurred at some intermediate citric acid concentration. The concentration of sodium chloride strongly effects on hydrogen yield in citric acid solution but without the effect on the hydrogen yield in acetic acid solution. The hydrogen generation rate from the magnesium scraps in 15 wt% acetic acid solution obviously exceeded that in 15 wt% citric acid solution, although the two organic solutions each had approximately equal moles of dissociable hydrogen atoms.
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