1,419 research outputs found
UMSL Bulletin 2023-2024
The 2023-2024 Bulletin and Course Catalog for the University of Missouri St. Louis.https://irl.umsl.edu/bulletin/1088/thumbnail.jp
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Plasma engineering of advanced functional materials for photocatalytic wastewater treatment
Semiconductor metal oxide photocatalyst with favourable light absorption and charge transport characteristics have been widely used as a photocatalyst in various applications, to name a few, energy harvesting and storage, environmental remediation and air pollution. Energy harvesting which comprises the full utilisation of the wide solar light (wavelength) spectrum has become a central point of research in the field of materials science and engineering. Hence, the development of sustainable materials from environmentally sustainable techniques which can absorb majority of the solar light spectrum has become a huge challenge. For efficient utilisation of solar energy in catalytic applications, it is important to create photocatalyst that can absorb the full solar spectrum involving ultraviolet (UV), visible (VIS) and near infrared (NIR) wavelengths. More than three decades, TiO2 and its composites have been widely researched academically and used industrially as a low-cost material for photocatalytic applications. However, the large bandgap of TiO2 limits its photocatalytic activity to the UV region which is just 3-5% of sunlight on Earth’s atmosphere. TiO2 also suffers from rapid recombination of photogenerated carriers (i.e., holes and electrons) thereby affecting its photocatalytic efficiency. Over the years, there has been active research in altering the chemistries of TiO2 to overcome these aforementioned shortcomings. The most recent advantage is the use of two dimensional (2D) materials because of its layered structure One of the unexplored and interesting layered structure is MXene. The aim of this thesis is to modify the chemical structure of Ti2C MXene to produce TiO2 as an efficient photocatalyst for absorbing solar energy especially in the UV and visible regions. As a compound of titanium and carbon, Ti2C MXene could facilitate the creation of TiO2 and carbonaceous materials hereby improving the photocatalytic performance. The abundance of surface terminal groups on Ti2C MXene allow for ease of surface modification and functionalisation. In this thesis, for the first time, the functionalisation of TiO2 from Ti2C MXene using a dry and low powered system, atmospheric pressure plasma jet (APPJ) is reported. This process involved using Ti2C nano colloidal ink with highly reactive oxygen plasma source which can tune the electronic properties (engineering bandgap) of Ti2C MXene in-situ while simultaneously printing on to a substrate. X-ray/Ultraviolet Photoelectron spectroscopy showed an additional density of states (DOS) close to valence band edge and changes to the Ti, O core level spectra due to the oxygen plasma functionalisation. Density functional Theory calculation suggests that the changes in the electron structure might be due to the influence of oxygen vacancies and hence the increase in efficiency of catalytic process. Also, time dependent oxygen plasma functionalisation studies reveal the morphology and size of the in-situ generated TiO2 nanoparticles varied from 5-8 nm with exceptionally high photocatalytic performance.
The second aim of the thesis is to create a heterostructure of Ti2C MXene with low cost and earth abundant graphitic carbon nitride, g-C3N4 (GCN) with visible light properties. For the first time, a lower power APPJ method was reported to produce a ternary in-situ TiO2/Ti2C/GCN heterostructure. In this thesis, GCN nanosheets were used as a semiconducting photocatalyst that could efficiently harvest the energy from visible light. Ti2C MXene nanosheets acted as an excellent electron sink while providing enhanced surface area which could facilitate the interfacial charge carriers. Structural studies show the formation of heterostructure formation between Ti2C MXene and GCN. Influence of morphology and hence changes to the optical properties were discussed. The synthesized ternary in-situ TiO2/Ti2C/GCN nanosheets showed enhancement in photocatalytic performance.
The third aim of my research was to integrate TiO2 onto earth abundant natural cellulose fibres. Utilising the power of low power atmospheric pressure plasma (APPJ) to in-situ anchor TiO2 onto cellulose fibres to prevent the thermal degradation and chemical instability leading to leaching of the oxides from the cellulose fibres. APPJ in the presence of highly oxidised species caused an increase in COO- bonds which provided a strong linkage between TiO2 and cellulose materials. Also, structural studies revealed polymorphic changes in the structure of cellulose materials that improved its crystallinity and surface area for photocatalytic applications. APPJ is also able to create oxygen vacancies in the TiO2 which further reduced the bandgap of as synthesized TiO2/cellulose nanocomposites that enhanced photocatalytic applications. Toxicity studies showed that TiO2 was not cytotoxic.
This plasma modified surfaces (of all the samples) show exceptional degradation of wastewater with ternary in-situ TiO2/Ti2C/GCN showing two times more improvement in methylene blue degradation (84% degradation) as compared to in-situ TiO2/Ti2C MXene (42% degradation). Also, TiO2/cellulose bionanocomposite showed excellent adsorptive-photocatalytic performance in degrading industrial waste dye providing a clear route as nanocomposites from research into industrialisation
UMSL Bulletin 2022-2023
The 2022-2023 Bulletin and Course Catalog for the University of Missouri St. Louis.https://irl.umsl.edu/bulletin/1087/thumbnail.jp
2023-2024 Catalog
The 2023-2024 Governors State University Undergraduate and Graduate Catalog is a comprehensive listing of current information regarding:Degree RequirementsCourse OfferingsUndergraduate and Graduate Rules and Regulation
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Policy options for food system transformation in Africa and the role of science, technology and innovation
As recognized by the Science, Technology and Innovation Strategy for Africa – 2024 (STISA-2024), science, technology and innovation (STI) offer many opportunities for addressing the main constraints to embracing transformation in Africa, while important lessons can be learned from successful interventions, including policy and institutional innovations, from those African countries that have already made significant progress towards food system transformation. This chapter identifies opportunities for African countries and the region to take proactive steps to harness the potential of the food and agriculture sector so as to ensure future food and nutrition security by applying STI solutions and by drawing on transformational policy and institutional innovations across the continent. Potential game-changing solutions and innovations for food system transformation serving people and ecology apply to (a) raising production efficiency and restoring and sustainably managing degraded resources; (b) finding innovation in the storage, processing and packaging of foods; (c) improving human nutrition and health; (d) addressing equity and vulnerability at the community and ecosystem levels; and (e) establishing preparedness and accountability systems. To be effective in these areas will require institutional coordination; clear, food safety and health-conscious regulatory environments; greater and timely access to information; and transparent monitoring and accountability systems
Handbook Transdisciplinary Learning
What is transdisciplinarity - and what are its methods? How does a living lab work? What is the purpose of citizen science, student-organized teaching and cooperative education? This handbook unpacks key terms and concepts to describe the range of transdisciplinary learning in the context of academic education. Transdisciplinary learning turns out to be a comprehensive innovation process in response to the major global challenges such as climate change, urbanization or migration. A reference work for students, lecturers, scientists, and anyone wanting to understand the profound changes in higher education
2023 GREAT Day Program
SUNY Geneseo’s Seventeenth Annual GREAT Day. Geneseo Recognizing Excellence, Achievement & Talent Day is a college-wide symposium celebrating the creative and scholarly endeavors of our students. http://www.geneseo.edu/great_dayhttps://knightscholar.geneseo.edu/program-2007/1017/thumbnail.jp
Fabrication of Novel In-Situ Remediation Tools for Unconventional Oil Contamination
The aftermath of unconventional oil (UO) accidents highlights the lack of preparedness of governments to deal with UO emergencies. Because bioremediation is considered slow process, physicochemical treatment processes are necessary in removing contaminants to constrain the spread of oil. In preliminary phase of study, bed systems for adsorption of oil compounds packed with modified dolomite were applied as pre-treatment for bioremediation systems. The high affinity of oil molecules to the active sites due to hydrophobic nature of dolomite surface, as well as low solubility of oil in water, resulted
in rapid process of oil adsorption on external surface of modified dolomite. UO contaminated site contain high concentration of polyaromatic hydrocarbons (PAHs). Thus, the final phase of study focused on finding enzyme mixture for biodegradation of PAHs contaminated sites for water and soil treatment. In this regard, screening of indigenous bacteria, identification of involved enzymes, and biodegradation tests were carried out.
Several combinations of the pre-selected strains were used to create most prompting consortium for enzyme production. To mimic in situ application of enzyme mixture, bioremediation of pyrene contaminated soil was carried out in soil column tests.
The average values of pyrene removal after 6 weeks indicated that the enzyme cocktail can be an appropriate concentration for soil enzymatic bioremediation in the soil column system. A bioinspired device was fabricated as a sustainable remedial method. Our results showed that after 200 seconds of circulating the enzyme solution 100% of anthracene in 1.5 L of 4.6 mg/L was removed from the beaker side. In addition to the circulation of PAH degrading enzymes in hollow fiber lumens, aliphatic degrading enzymes confined in multilayer nanofibrous membrane systems play an important role in the removal of oily compounds. Based on our studies, modified polyimide aerogels were suitable to support enzyme immobilization. The degradation tests clearly showed that immobilized enzymes had biodegradation ability for model substrate in contaminated water. Our results confirmed that immobilization of cocktail enzyme mixture enhanced their storage stability, more than 45% of its residual activity at 15 ± 1 ºC for 16 days. This study could set the guideline for the enzymatic bioremediation of aromatic pollutants especially polycyclic aromatic hydrocarbons in highly contaminated soil and water body
Oxidative dehydrogenation of ethane with carbon dioxide over iron-nickel nano-alloys supported on metal oxide overlayers
The CO2-mediated oxidative dehydrogenation of ethane (CO2-ODHE) is one of the promising alternative routes for simultaneous conversion of ethane and the greenhouse gas (GHG) CO2 into high-demand monomers: ethylene and CO [1,2]. It has been extensively investigated on oxide catalysts with those based on Cr, V and Ga exhibiting high yields and selectivity for ethylene but those deactivate rapidly [3–12]. The reaction follows a Mars van Krevelen mechanism where the oxide is partially reduced upon ethane activation and subsequently re-oxidized upon CO2- activation [13]. Thus, suitable redox properties as well as Lewis acidity of metal oxides are some essential properties governing catalytic performance [13–15]. The lower stability of these materials is linked to their failure to act as multifunctional catalysts that can prevent carbon buildup via the dissociation of CO2 while co-activating ethane. Promoters such as Fe-based oxides have been studied to enhance the CO2-activation functionality and stability of the oxides [5]. A Density Functional Theory (DFT) study suggested that bimetallic alloys can have superior activity for CO2-activation compared to their monometallic counterparts [16]. Therefore, bimetallic alloys in conjunction with metal oxides may serve as stable bifunctional CO2-ODHE catalysts with enhanced CO2-activation ability. Improved CO2-activation can boost the re-oxidation rate of the metal oxide via a spillover-type mechanism and aid in coke removal via the reverse Boudouard reaction [5,11]. Recent studies have already demonstrated this experimentally with a series of supported FexNiy catalysts prepared via impregnation which, depending on Fe : Ni ratio and support, can promote either the CO2-ODHE or the competing ethane dry-reforming (DRE) reactions with enhanced CO2-activation [17,18,18–20]. However, composition and crystallite size uniformity are difficult to attain via impregnation as Ni and Fe oxide phases present in parallel make it challenging to extract the influence of the FexNiy alloy metallic composition [21]. This work aims to synthesize catalytically active metal oxide overlayers of a comparable pore structure, anchor FexNiy nano-alloys of uniform composition with Fe and Ni in close proximity and investigate the combined effect of the overlayer support's acidity/reducibility and alloy composition on the catalytic performance under CO2-ODHE conditions. The close proximity of Fe and Ni in the alloy is introduced by the use of oxidic Ni-ferrite spinel structures as precursors of the alloy which is formed upon their reduction in H2 atmosphere and was found to exist as a mixture of a bcc and an fcc phases depending on Fe : Ni ratio. A higher Fe content in the alloy increases the fraction of the bcc phase as confirmed via H2-TPR studies in in situ XRD. In situ XRD temperature-programmed CO2-activation studies also revealed that CO2 is only able to react with the bcc phase of the alloy which is re-oxidised into the oxidic Niferrite spinel while the fcc phase is stable against re-oxidation. While they deactivate rapidly due to a limited re-oxidation and coking caused by insufficient CO2- activation, the bare metal oxide overlayers exhibit an initial activity that reduces with a decrease of the surface acid site strength until a minimum is reached and then slightly increases with increasing basicity under CO2-ODHE conditions. Their catalytic stability increases with weakening of the acid site strength. Decreasing the overlayer acidity enhances the CO2-ODHE/DD (DD : direct dehydrogenation) activity resulting in increased ethylene and decreased CO selectivity. Spent catalyst analysis revealed the formation of surface carbonaceous deposits suspected to cause catalyst deactivation. Increasing the concentration of CO2 in the feed results in improved and sustained CO2-activation which enhances the reverse Boudouard reaction and improves the catalyst stability by reducing carbon deposition while reducing ethylene and increasing CO selectivity. Deposition of the FexNiy nano-alloys of Fe : Ni atomic ratios of 1, 3 and 5 on the reducible and acidic CrOx@Al2O3 results in an alloy composition-dependent catalyst performance, while the alloys are essentially inactive over the less acidic and unreducible ZrOx@Al2O3. This clearly confirms a bifunctional character of these materials and reveals that their catalytic performance depends on both the overlayer reducibility/acidity and the metallic composition of the alloy. Over CrOx@Al2O3, the alloy enhances the CO2-activation functionality with increasing Ni-content boosting the overall activity and stability of the catalyst. However, with increasing Ni-content, the CO selectivity increases while ethylene selectivity reduces due to the suppressed CO2-ODHE/DD activity and promotion of the competing DRE reaction. The target CO2-ODHE/DD reaction activity is maximal at an overall Fe : Ni atomic ratio of 5, about 10% at a ratio of 3 and completely suppressed at a ratio of 1. Spent catalyst analysis revealed formation of surface carbonaceous deposits and that the bcc phase of the alloy is re-oxidised into the Ni-ferrite oxidic spinel phase while the fcc phase of the alloy is stable against re-oxidation during the reaction. Increased CO2 concentration in the feed has similar effects as described for the bare overlayers. Deposition the Fe3Ni1 and Fe5Ni1 nano-alloys on GaOx@Al2O3, VOx@Al2O3, SmOx@Al2O3 and TiOx@Al2O3 revealed that despite the alloy composition, a predominant DRE activity is observed over the highly acidic and reducible VOx@Al2O3. While CrOx@Al2O3 and GaOx@Al2O3 show a similar performance when tested bare, the addition of the Fe3Ni1 and Fe3Ni1 alloys on the GaOx@Al2O3 overlayer results in a high CO2-ODHE/DD activity with stability decreasing with increasing Fe-content. Over TiOx@Al2O3, the Fe3Ni1 nano-alloy exhibits a similar behaviour as over GaOx@Al2O3 while higher iron contents resulted in an inactive catalyst. Over SmOx@Al2O3 no alloy composition yields appreciable catalytic activity. The CO2-ODHE/DD behaviour of Fe3Ni1/GaOx@Al2O3 is in stark contrast to the high DRE activity over Fe3Ni1/CrOx@Al2O3 emphasising that a specific alloy composition exists for each overlayer to yield a stable and dominating CO2-ODHE/DD or DRE activity. For a high and stable CO2-ODHE/DD activity, the optimum in atomic Fe : Ni ratio was found to be between the 3 and 5 at intermediate-intermittent overlayer acidity. In addition to improving stability, increased CO2 concentration in the feed was found to significantly accelerate an observed active site re-construction during reaction which results in formation of more CO2-ODHE/DD sites
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