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Removal of emulsified water is a challenge in oil sands and heavy oil processing. The flocculation and coagulation of emulsified water droplets depend on the interactions between the water droplets covered mainly by asphaltenes and oil-contaminated fine solids. To quantitatively evaluate the stability of water-in-diluted bitumen emulsions, this research determined the interactions between asphaltene surfaces in model oils, heptane, toluene or a mixture of the two known as heptol, by colloidal force measurements using atomic force microscopy (AFM) in combination with the Langmuir-Blodgett technique. The effect of aromaticity of the solvents, temperature and water content of the solvents on asphaltenes-asphaltenes interactions was systematically investigated. The results showed that the interaction forces between asphaltenes are highly sensitive to the aromaticity of the organic solvents. In solvents of higher aromaticity, a repulsive force existed between asphaltene surfaces; whereas in solvents of lower aromaticity, a weak attraction was detected. The transition from repulsion to attraction indicates that it is possible to control asphaltenes-asphaltenes interactions, and ultimately to control the stability of asphaltene-stabilized water droplets in oil, through tuning the aromaticity of the organic solvents. By fitting the measured force profiles with theoretical models, the nature of the forces was determined, which provides insights into the mechanisms of asphaltene-stabilized water-in-oil emulsions. The concomitant benefit of the results from the direct force measurement is to predict asphaltene precipitation with change of solvent composition. Oil-contaminated fine solids not only help stabilize water-in-diluted bitumen emulsions but are detrimental to bitumen upgrading. To control the wettability of these fine solids, a preliminary study was carried out in this work to explore the potential of ethyl cellulose (EC), an effective demulsifier for water-in-diluted bitumen emulsion, as a surface wettability modifier of the oil-contaminated solids. It was found that EC is able to reduce the surface hydrophobicity of the asphaltene- and bitumen-contaminated solids and thus enhances their removal from bitumen froth. The mechanism of increased wettability by EC addition was determined by quartz crystal microbalance with dissipation (QCM-D) and AFM topographical imaging. The results from this study can help establish the criteria for selecting and developing chemical modifiers for applications in wettability control of oil-contaminated solids. / Chemical Engineering

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The goal of this research is to improve an extractive metallurgy process based on solvent extraction. This process should fit the exploitation of small local copper-rich deposits. In these conditions, the plant has to be as compact as possible in order to be easily transported from one location to a subsequent one. Improved extraction kinetics could ensure a high throughput of the plant despite its compactness. In addition, the extraction reagent should not be damaging for the environnement. On this basis, we propose to use ultrasound-assisted solvent extraction. The main idea is to increase the extraction kinetics by forming an emulsion in place of a dispersion thanks to the intense cavitation produced by ultrasound. The benefit of this method is to improve the copper extraction kinetics by increasing the interfacial surface area and decreasing the width of the diffusion layer. We studied the implementation of an highly branched decanoic acid (known as Versatic- 10®acid) as a copper extraction reagent dispersed in kerosene. Emulsification is monitored through the Sauter diameter of the organic phase droplets in aqueous phase. This diameter is measured during pulsed and continuous ultrasound irradiation via a static light scattering technique. The phenomenon of emulsification of our system by ultrasound is effective, and the emulsification process carried out in the pulsed ultrasound mode is at least as efficient as the emulsification obtained under continuous mode. No improvement of emulsification is observed beyond a threshold time of the ultrasound impulse. This may be attributed to a competition between disruption and coalescence. The use of mechanical stirring combined with pulsed ultrasound allows to control the droplet size distribution. In presence of ultrasound, the extraction kinetics of Versatic-10 acid is multiplied by a factor ten, and therefore reached a value similar to the kinetics observed without ultrasound with an industrial extractant such as LIX-860I®(Cognis). Extraction kinetics measurements are carried out by monitoring the copper ion concentration in the aqueous phase with an electrochemical cell. We conclude that ultrasound-assisted emulsification can be implemented under certain conditions. Emulsification is a first step, and the following destabilization step has to be studied. The device using ultrasound-assisted emulsification should be followed by an efficient settling-coalescing device. A possible solution would be to promote emulsion destabilization by increasing the ionic strength with an addition of MgSO4, a salt that is not extracted by the extraction reagent in the considered range of pH.

This study examined the effects of a microbubble emulsion (ME) combined with sonic or ultrasonic agitation, on irrigation dynamics and reduction of biofilm bacteria. High-speed imaging was used to characterize the bubble dynamics generated in ME by sonic or ultrasonic agitation within polymer teeth. 5.25% NaOCl or ME was sonically or ultrasonically agitated in canals of extracted teeth with 7-day-old Enterococcus faecalis biofilms. Dentinal shavings were sampled and colony-forming units (CFU) enumerated. Mean log CFU/ml values were analyzed with ANOVA and post-hoc tests. Strongly oscillating and vaporizing bubbles were generated within ME during ultrasonic, but not sonic agitation. Post-treatment biofilm CFU were significantly lower in the ultrasonic agitation (P=0.000) of ME group than in the ultrasonic (P=0.009) and sonic agitation (P=0.006) of NaOCl groups. The synergistic effect of ME combined with ultrasonic agitation enhanced bubble dynamics and reduced E. faecalis biofilm bacteria beyond the level achieved by agitation of NaOCl.

This study examined the effects of a microbubble emulsion (ME) combined with sonic or ultrasonic agitation, on irrigation dynamics and reduction of biofilm bacteria. High-speed imaging was used to characterize the bubble dynamics generated in ME by sonic or ultrasonic agitation within polymer teeth. 5.25% NaOCl or ME was sonically or ultrasonically agitated in canals of extracted teeth with 7-day-old Enterococcus faecalis biofilms. Dentinal shavings were sampled and colony-forming units (CFU) enumerated. Mean log CFU/ml values were analyzed with ANOVA and post-hoc tests. Strongly oscillating and vaporizing bubbles were generated within ME during ultrasonic, but not sonic agitation. Post-treatment biofilm CFU were significantly lower in the ultrasonic agitation (P=0.000) of ME group than in the ultrasonic (P=0.009) and sonic agitation (P=0.006) of NaOCl groups. The synergistic effect of ME combined with ultrasonic agitation enhanced bubble dynamics and reduced E. faecalis biofilm bacteria beyond the level achieved by agitation of NaOCl.

Ethylene-vinyl acetate emulsion is the copolymer of vinyl acetate and ethylene, which has been developed as a powerful adhesive base. It effectively bonds substrates such as wood, cotton cloth, hardboard and paperboard. After modifying by adhesives producers, EVA emulsion can bond a great variety of surfaces, particularly effective in bonding polyvinyl chloride films and narrow-pore materials. Adhesives producers provides customized products according to different end users¡¦ needs and consequently have to keep raw materials in stock until orders are placed. The ordering of EVA emulsion is an important issue for adhesives producers because of the seasonal demand pattern and price fluctuation of raw materials. Furthermore, under certain transporting and order restrictions, the ordering quantity is fixed and delivery time has to be made in advance. The multi-period inventory models, including EOQ and ROP, are not suitable for analyzing the ordering of EVA emulsion due to the presupposition of unlimited period. This research is based on the case study for NP chemical, using modified ROP model to explore how the selection of service level and delivery time can effect safety stock, probability of shortage, and inventory cost under the conditions of limited period, seasonal demand, given order quantity, and pre-selecting delivery points. The study also constructs a liquid raw material inventory model with fluctuating price and given order quantity in order to determine the optimal combination of delivery points. The conclusion of this study are presented as follows: 1.Service level doesn¡¦t directly effects the probability of shortage and inventory cost in limited period. 2.The combination of delivery points is the key decision factor because of its causal relationship with the probability of shortage and inventory cost. 3.The optimal combination which leads to the lowest inventory cost can be determined by using the inventory model introduced in this study.

Techn. Univ., Inst. für Thermische Verfahrenstechnik, Diss.--Hamburg-Harburg, 2006. / Literaturverz. S. 142 - 145.

Thesis (Ph. D.)--Lehigh University, 2002. / Includes bibliographical references and vita.