Copper oxide nanoparticles (NPs) are used in an expanding range of industries including a potential for agricultural applications as a fungicide. Accidental spills or misapplication of CuO NPs may lead to soil contamination. Plant roots exude a wide range of organic chemicals for bioprotection and to enhance bioavailability of nutrients. Many of these chemicals are metal chelators that may increase the solubility of CuO NPs, thus enhancing the impact of these NPs on plants. This work was directed towards understanding which plant exudates force increased solubility of CuO NPs and to determine if the level of NP in the growth matrix drives a feedback effect, regarding composition and quantity of exudates. Wheat seedlings (Triticum aestivum cv Deloris) were grown in a sand matrix for 10 days after 3 days of germination. The sand was amended with sublethal doses of CuO NPs from 0 to 300 mg Cu/kg dry sand. Sand was selected as the solid growth matrix as a proxy for soil in terms of plant root morphology, mechanical impedance and water stress, while providing a low background of dissolved organic carbon for the isolation of root exudates. After plant growth, the pore water was collected from the sand by vacuum filtration and analyzed. By coupling analytic techniques including Triple Quad Mass Spectroscopy and ion chromatography with geochemical modeling, we have identified citrate and the phytosiderophore, deoxymugineic acid (DMA) as chelators that drove the majority of dissolution of CuO NPs, especially DMA at higher CuO NP doses. Altered biogeochemistry within the rhizosphere was correlated with increased plant uptake of Cu and bio-response via exudate type, quantity and metal uptake. Exposure of wheat to CuO NPs lead to dose-dependent reduction in Fe, Ca, Mg, Mn and K in roots and shoots. This work is relevant to growth of commercially important crop wheat in the presence of CuO NPs as a fertilizer, fungicide or a pollutant.

No description available.

Metal oxide semiconductor (MOS) gas sensors have proven to be useful in many applications, ranging from detection of hazardous gases to monitoring of air quality. The demand for power efficient and high performance gas sensors has seen an increase in situations facing contemporary society. Currently it is common for sensors to employ an energy inefficient heater to provide for the optimal working temperature of the sensor. Light activation has been proposed as an alternative that could possibly improve modern gas sensors by decreasing energy utilization as well as increasing sensitivity and selectivity. The purpose of the following project is to explore the mechanisms and characteristics of light activated gas sensing using cuprous oxide (Cu2O), such that the findings may contribute to the development of power efficient gas sensors able to distinguish between gases at low concentrations. Several Cu2O-sensors with thicknesses of 300, 500 and 700 nm were examined, many of which also were doped with materials such as silver, graphene and titanium. Multiple types of measurements were performed where the sensors were exposed to nitrogen and carbon dioxide gas under illumination from one of three distinct light sources. The results show that conditions such as low light intensities, doping the sensors and air as the operating environment (compared to nitrogen gas) are beneficial for the carbon dioxide response under light activation. However, these findings are only indications and would need confirmation by additional measurements, both in terms of variation and repetition, under improved conditions.

This research is directed towards understanding the mechanisms associated with the manufacture of solid microspheres less than 100 [micrometers], from liquid droplets with nanosuspensions in a microfluidic T-junction, which are heated downstream of the channel. Preliminary material characterization tests on colloidal suspensions of alumina and copper oxide demonstrate promising temperature dependent viscosity results indicating solidification in the temperature range of 40°C-50°C. The solidification mechanism is referred to as Temperature Induced Forming and is described by polymeric bridges formed between nanoparticles in suspension at elevated temperatures, resulting in a solid structure. The polymer network results from the ionization of alumina at elevated temperatures whereby polymeric binders adhere to newly formed charged sites on the alumina particle. This study aims to investigate the aspects of manufacturing microstructures in microfluidic Tjunctions, droplet morphology, size and frequency of production. Preliminary low solid concentration experiments (1%-10% volume concentration of alumina in H2O) have indicated solidification and a regression in droplet diameter when heated near the saturation temperature of the water used to disperse the particles. The microstructures from this solidification process are uniform and are estimated to be 30 [micrometers] in size.

No description available.

Yes / In this paper, oxidative desulfurization (ODS) process is studied for the purpose of removing the sulfur components from light gas oil (LGO) via experimentation and process modeling. A recently developed (by the authors) copper and nickel oxide based composite nano-catalyst is used in the process. The ODS experiments are conducted in a batch reactor and air is used as an oxidizer under moderate operation conditions. Determination of the kinetic parameters with high accuracy is necessary of the related chemical reactions to develop a helpful model for the ODS operation giving a perfect design of the reactor and process with high confidence. High conversion of 92% LGO was obtained under a reaction temperature of 413 K and reaction time of 90 min for synthesized Cu Ni /HY nano-catalyst. Here model based optimization technique incorporating experimental data is used to estimate such parameters. Two approaches (linear and non-linear) are utilized to estimate the best kinematic parameters with an absolute error of less than 5% between the predicted and the experimental results. An environmentally friendly fuel is regarded the main goal of this study, therefore the optimization process is then employed utilizing the validated model of the prepared composite nano-catalyst to get the optimal operating conditions achieving maximum conversion of such process. The results show that the process is effective in removing more than 99% of the sulfur from the LGO resulting in a cleaner fuel.

Yes / Production of clean fuel has recently become one of the most important goals for petroleum refining industries. The objective of this work is to obtain such clean fuel using simple and easy process under safe conditions. For this purpose, batch oxidative desulfurization (ODS) process is considered here to remove sulfur compounds found in light gas oil using a new composite synthetic homemade nano-catalyst. First the support for the new catalyst, which is HY zeolite nanoparticles, is prepared using sol-gel method. The support is then employed to generate the synthetic composite nano-catalyst which is made of copper oxide and nickel oxide using the impregnation method with different proportions of the active components such as: 5% CuO +25 % NiO, 10 % CuO +20 % NiO, 15 % CuO +15 % NiO, 20 % CuO +10 % NiO and 25 % CuO +5% NiO. An excellent distribution of the active metals with high surface area and pore volume as a result high activity has obtained. A fully automated batch reactor is used for the oxidative desulphurization of sulfur compounds and the performance of the new nano-catalyst at different safe reaction conditions (reaction temperature from 353−413 K, reaction time from 30−90 min) is evaluated in terms of sulfur removal.

Water and CO adsorptions were studied over the stoichiometric and the oxygen-deficient Cu₂O(111) surfaces, using thermal desorption spectroscopy (TDS), ultraviolet photoelectron spectroscopy (UPS), and X-ray photoelectron spectroscopy (XPS). Water is the only desorbing species detected in TDS and the extent of dissociation is unaffected by the surface condition: ≃ 0.25 monolayers of water dissociate on Cu₂O(111) regardless of surface condition. The local defect environment around oxygen vacancies does not play a significant role in the activity of the Cu₂O(111) surface for the dissociation of water. CO is found to bind molecularly to the surface through the carbon atom and with a heat of adsorption of 22 kcal/mol, higher value than that of CO on Cu₂O(100) (16.7 kcal/mol). This suggests that the local geometry of adsorption sites may play an important role in the way CO binds to Cu₂O surfaces. Electronic changes upon CO adsorption and the higher heat of adsorption indicate an increased σ-donor character for CO, with some π-backbonding interactions. The local defect environment around oxygen vacancies does not appear to affect CO adsorption on Cu₂O(111) surfaces. / Master of Science

The purpose of this study was to investigate the supported catalyst of the type CuO-Al₂O₃ which has been described by Lockwood and Frazer (13). This type of catalyst is unique in that it has a high activity at low temperatures, is suitable for use at high temperatures and has been reported to be truly catalytic in the oxidation of carbon monoxide. Lockwood and Frazer (15) have described the preparation of a catalyst of this type. Their description of the method of preparation and of the quantities of materials used is rather inadequate for an exact duplication of the catalyst which they prepared and studied. The method of procedure used in the study of this catalyst has been to vary both the composition and heat treatment of the catalysts and to observe the subsequent change in catalytic activity. 1. Increasing the copper oxide content of the copper oxide-aluminum catalysts increases the activity of the catalysts at least over the composition range studied. 2. Increasing the temperature to which the copper oxide-aluminum oxide catalysts are heated increases the activity. 3. The temperatures required for the catalysts to exhibit 100% activity are all above 270°C. 4. It was found impossible to reproduce the copper oxide-aluminum catalyst which was prepared by Lockwood and Frazer. 5. A catalyst prepared from pure copper oxide was more active than any of the catalysts which were studied. / M.S.

Les équipes micro-capteurs (IM2NP) et capteurs de gaz (LMMA) développent des capteurs à base de couches minces de CuxO et étudient leurs réponses électriques sous O3. Les travaux de cette thèse ont pour but de mieux comprendre l’interaction solide-gaz à l’échelle atomique en simulant l’adsorption de l’O3 sur les surfaces (111) du CuO et du Cu2O. Pour cela nous avons utilisé la DF T (Density Functional Theory) dans le cadre de deux approximations de la fonctionnelle : la LDA (Local Density Approximation) et la GGA (Generalized Gradient Approximation).Pour le CuO, la correction de Hubbard (DF T + U) a été également prise en compte pour reproduire correctement les comportements semiconducteuret antiferromagnétique du matériau. Tous les calculs ont été menés avec le code SIESTA et montrent que pour les deux matériaux, l'ozone s’adsorbe sur la surface sans défauts, sans se dissocier, induisant un dopage p du matériau. Ceci est en accord avec la diminution de la résistance électrique mesurée expérimentalement sous ozone. Ensuite, l’ozone se dissocie en formant une molécule de O2 et un atome d’oxygène qui restent adsorbés. Cette étape ne semble pas modifier le dopage. Par contre lorsque le capteur n’est plus en présence d'O3, la molécule d’O2 désorbe et le dopage est annihilé. Dans ce mécanisme les énergies mises en jeu sont du même ordre de grandeur pour CuO ou pour Cu2O (allant de −3 eV à −1 eV). Dans l’objectif de développer un capteur de gaz, le CuO, plus facile à obtenir par les techniques de dépôt courantes en microélectronique, semble donc être plus pertinent que le Cu2O, qui a une réponse similaire (voire moindre) mais dont il est difficile d’obtenir une phase pure. / Micro-sensors (IM2NP) and gas sensors (LMMA) team develop sensors based on CuO and Cu2O thin layers and study their electrical responses to O3. The aim of this thesis is a better understanding of the solid-gas interactions at the atomic scale by simulating the adsorption of O3 molecule on the (111) surfaces of CuO and Cu2O. Simulations were performed using the DF T (Density Functional Theory) within two functional approximations : the LDA (Local Density Appriximation) and GGA (Generalized Gradient Approximation). In the case of CuO, the Hubbard correction (DF T + U) was taken into account to properly reproduce the semiconductor and antiferromagnetic behaviors of the material. All calculations were performed with the SIESTA code and show that for the CuO as for Cu2O, O3 is adsorbed on the defect-free surface, without dissociating inducing a p-doping of the material. This observation is consistent with the decrease in electrical resistance measured experimentally under ozone. In a second stage ozone dissociates into a molecule of O2 and an oxygen atom which remains adsorbed. This step does not appear to change the doping. However, when the sensor is no longer in the presence of ozone, O2 molecule is desorbed and doping disappears. In this mechanism, the energies involved during the adsorption or the dissociation of ozone are of the same order of magnitude for CuO or Cu2O (ranging from −1 eV to −3 eV). Aiming to develop a gas sensor, and since the CuO material is easier to obtain by standard deposition techniques (RF sputtering), it seems to be more appropriate than the Cu2O, which has a similar response (even lower) but is more difficult to synthesize in a pure phase.