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- All Subjects: chemical engineering
- Member of: Barrett, The Honors College Thesis/Creative Project Collection
Description
In our modern world the source of for many chemicals is to acquire and refine oil. This process is becoming an expensive to the environment and to human health. Alternative processes for acquiring the final product have been developed but still need work. One product that is valuable is butanol. The normal process for butanol production is very intensive but there is a method to produce butanol from bacteria. This process is better because it is more environmentally safe than using oil. One problem however is that when the bacteria produce too much butanol it reaches the toxicity limit and stops the production of butanol. In order to keep butanol from reaching the toxicity limit an adsorbent is used to remove the butanol without harming the bacteria. The adsorbent is a mesoporous carbon powder that allows the butanol to be adsorbed on it. This thesis explores different designs for a magnetic separation process to extract the carbon powder from the culture.
ContributorsChabra, Rohin (Author) / Nielsen, David (Thesis director) / Torres, Cesar (Committee member) / Barrett, The Honors College (Contributor) / Chemical Engineering Program (Contributor)
Created2015-05
Description
Layered double hydroxides (LDHs), also known as hydrotalcite-like materials, are extensively used as precursors for the preparation of (photo-)catalysts, electrodes, magnetic materials, sorbents, etc. The synthesis typically involves the transformation to the corresponding mixed metal oxide via calcination, resulting in atomically dispersed mixed metal oxides (MMOs). This process alters the porosity of the materials, with crucial implications for the performance in many applications. Yet, the mechanisms of pore formation and collapse are poorly understood. Combining an integrated in situ and ex situ characterization approach, here we follow the evolution of porosity changes during the thermal decomposition of LDHs integrating different divalent (Mg, Ni) and trivalent (Al, Ga) metals. Variations in porous properties determined by high-resolution argon sorption are linked to the morphological and compositional changes in the samples by in situ transmission electron microscopy coupled with energy dispersive X-ray spectroscopy, which is facilitated by the synthesis of well crystallized LDHs of large crystal size. The observations are correlated with the phase changes identified by X-ray diffraction, the mass losses evidenced by thermogravimetric analysis, the structural changes determined by infrared and nuclear magnetic resonance spectroscopy, and the pore connectivity analyzed by positron annihilation spectroscopy. The findings show that the multimetallic nature of the LDH governs the size and distribution (geometry, location, and connectivity) of the mesopores developed, which is controlled by the crystallization of the MMO phase, providing key insights for the improved design of porous mixed metal oxides.
ContributorsMurty, Rohan Aditya (Author) / Deng, Shuguang (Thesis director) / Nielsen, David R. (Committee member) / Chemical Engineering Program (Contributor) / Barrett, The Honors College (Contributor)
Created2017-05