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Evaluation of Demulsifiers by Modified Thin Liquid Film Technique Open Access


Other title
Emulsion stability
Thin liquid film
Type of item
Degree grantor
University of Alberta
Author or creator
Ma, Xinrui
Supervisor and department
Xu, Zhenghe (Chemical and Materials Engineering)
Examining committee member and department
Liu, Qingxia (Chemical and Materials Engineering)
Leung, Juliana (Civil and Environmental Engineering)
Xu, Zhenghe (Chemical and Materials Engineering)
Department of Chemical and Materials Engineering
Chemical Engineering
Date accepted
Graduation date
2017-06:Spring 2017
Master of Science
Degree level
The formation of stable water-in-oil emulsions during oil sands extraction process causes a number of operational issues, such as equipment corrosion, storage and transportation problems. One common method for emulsion breakup in industry is to use chemical demulsifiers. The chemical demulsifiers decrease the stability of water-in-oil emulsions associated with the properties of the thin liquid films formed between two closely approached water droplets. In this thesis, the Thin Liquid Film Technique and the novel Modified Thin Liquid Film Technique were introduced to generate the intervening liquid films from droplet-droplet interactions for demulsification study. For the first time a systematic comparison between two demulsifiers addition protocols was conducted using EC300 as demulsifiers to clarify the possible effect of order of demulsifier addition on demulsification. The comparison of premixing system and dosing system showed that modified thin liquid film technique can more closely mimic the real demulsification process in industry and can be used to study the molecular mechanism of how demulsifiers break interfacial films. The measurement of film stability against coalescence after adding different demulsifiers showed that EC300 and EC4 have slightly greater but very similar film breaking performance, despite of their dramatically different molecular weights. The film breaking efficiency of EO-PO 86H was lower than EC300 and EC4, but greater than EO-PO 16H, both being commercial demulsifiers. However, the concentration window of EO-PO for breaking the film was much wider than that of EC. The morphology of diluted bitumen films after dosing EC300 revealed the penetration into the diluted bitumen-water interface, causing asphaltene aggregation and forcing the interfacial film rupture into small fragments. High concentration of EC300 can form films with greater thickness, leading to overdose of the demulsifier. This study shows that film breaking efficiency of demulsifiers is concentration-dependent and closely related to emulsion destabilization. This finding as well as the mechanisms of demulsification and overdose effect revealed from this work are required to be carefully considered when designing new demulsifiers or applying current demulsifiers to dewatering of water-in-petroleum emulsions.
This thesis is made available by the University of Alberta Libraries with permission of the copyright owner solely for the purpose of private, scholarly or scientific research. This thesis, or any portion thereof, may not otherwise be copied or reproduced without the written consent of the copyright owner, except to the extent permitted by Canadian copyright law.
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