Matching Items (2)
Description
A new photocatalytic material was synthesized to investigate its performance for the photoreduction of carbon dioxide (CO2) in the presence of water vapor (H2O) to valuable products such as carbon monoxide (CO) and methane (CH4). The performance was studied using a gas chromatograph (GC) with a flame ionization detector (FID) and a thermal conductivity detector (TCD). The new photocatalytic material was an ionic liquid functionalized reduced graphite oxide (IL-RGO (high conductive surface))-TiO2 (photocatalyst) nanocomposite. Brunauer-Emmett-Teller (BET), X-ray photoelectron spectroscopy (XPS), Raman spectroscopy, and UV-vis absorption spectroscopy techniques were employed to characterize the new catalyst. In the series of experiments performed, the nanocomposite material was confined in a UV-quartz batch reactor, exposed to CO2 and H2O and illuminated by UV light. The primary product formed was CO with a maximum production ranging from 0.18-1.02 µmol(gcatalyst-hour)-1 for TiO2 and 0.41-1.41 µmol(gcatalyst-hour)-1 for IL-RGO-TiO2. A trace amount of CH4 was also formed with its maximum ranging from 0.009-0.01 µmol(gcatalyst-hour)-1 for TiO2 and 0.01-0.04 µmol(gcatalyst-hour)-1 for IL-RGO-TiO2. A series of background experiments were conducted and results showed that; (a) the use of a ionic liquid functionalized reduced graphite oxide -TiO2 produced more products as compared to commercial TiO2, (b) the addition of methanol as a hole scavenger boosted the production of CO but not CH4, (c) a higher and lower reduction time of IL-RGO as compared to the usual 24 hours of reduction presented basically the same production of CO and CH4, (d) the positive effect of having an ionic liquid was demonstrated by the double production of CO obtained for IL-RGO-TiO2 as compared to RGO-TiO2 and (e) a change in the amount of IL-RGO in the IL-RGO-TiO2 represented a small difference in the CO production but not in the CH4 production. This work ultimately demonstrated the huge potential of the utility of a UV-responsive ionic liquid functionalized reduced graphite oxide-TiO2 nano-composite for the reduction of CO2 in the presence of H2O for the production of fuels.
ContributorsCastañeda Flores, Alejandro (Author) / Andino, Jean M (Thesis advisor) / Forzani, Erica (Committee member) / Torres, Cesar (Committee member) / Arizona State University (Publisher)
Created2014
Adaptation of Camponotus floridanus’ Cuticular Hydrocarbon Profile under High Temperature Conditions
Description
Insects are small creatures highly susceptible to water loss. A major factor in the prevention of water loss through an insect’s cuticle are their cuticular hydrocarbons (CHC), a lipid layer consisting mostly of long-chain hydrocarbons. CHCs consist of different molecules called alkanes, alkenes, and methyl branched hydrocarbons which all have varying levels of hydrophobicity. Ants are a massively abundant family of insects with important roles in the ecosystem that also utilize CHCs. Camponotus floridanus isare athe native ant species of the Florida Keys which areis known to have variable environmental temperature. Being exposed to temperatures as high as 35 °C, these ants are expected to have mechanisms that allow them to adapt to their environment. It was hypothesized that CHCs may change in concentration or composition as a means to combat the changes in cuticular permeability due to the variable temperatures that the ants experience. We therefore used C. floridanus worker ants to learn more about CHC plasticity in insects when exposed to elevated temperatures. We found four CHC componentspeaks that showed a statistically significant increase in concentration when comparing the control to treatment colonies: 3,7 dimethyl C31, an underdetermined methyl branched C31, 3,7,11 trimethyl C31, and an undetermined tetramethylbranched C31. These significant changes in concentration occurred on longer chain hydrocarbons. Under further examination, it was found that there was a strong positive correlation between elution time and the differences in medians of peak area between control and treatment colonies. This shows that there was a shift in the CHC profile resulting in an increased concentration of longer chained methyl-branched hydrocarbons. It also suggests that branched hydrocarbons also play some role in the water proofing mechanism of C. floridanus.
ContributorsOn, Thomas (Co-author) / On, Tyler (Co-author) / Liebig, Juergen (Thesis director) / Harrison, Jon (Committee member) / Murdock, Tyler (Committee member) / School of Life Sciences (Contributor) / Barrett, The Honors College (Contributor)
Created2020-05