期刊
COLLOIDS AND SURFACES A-PHYSICOCHEMICAL AND ENGINEERING ASPECTS
卷 466, 期 -, 页码 197-202出版社
ELSEVIER SCIENCE BV
DOI: 10.1016/j.colsurfa.2014.11.050
关键词
Magnetic nanoparticle; Emulsion; Demulsification; Oleic acid; Magnetite; Crude oil
资金
- National Natural Science Foundation of China [21173135]
- Specialized Research Fund for the Doctoral Program of Higher Education of China [20110131130008]
Most produced crude oil and oily wastewater from oilfields typically exist in the form of emulsions; this makes their demulsification a very challenging process. Chemical demulsifiers are commonly employed to enhance demulsification efficiency (E-D). However, there is still an urgent need to develop more efficient techniques and demulsifiers to meet eco-friendly and economically competitive requirements. In this study, magnetic demulsification of single-layer oleic acid-coated magnetite (Fe3O4@OA) nanopartides as a demulsifier for cyclohexane-diluted crude oil-in-water nanoemulsions (denoted as CO-NEs) was investigated under an external magnetic field. The effects of the dosage and wettability of the demulsifier, the pH of the CO-NEs, and the demulsification operation process on the ED were examined. The ED increased with increasing Fe3O4@OA dosage and a high ED of 97% was reached, which demonstrates the potential of Fe3O4@OA nanoparticles as a magnetic demulsifier for crude oil-containing emulsions from oilfields. The ED is related to the wettability (or water contact angle) of the magnetic nanoparticles, and a maximum ED was observed at a water contact angle of similar to 90. The E-D was almost unchanged in the pH range of 4.0-7.5, while it gradually decreased as the pH rose from 8.0 to 11.0. Multistep demulsification exhibited a higher ED than the single-step operation when the same amounts of demulsifier were used. The Fe3O4@OA nanoparticles exhibited good recyclability; no significant change in the ED of the recycled Fe3O4@OA after demulsification was observed over five cycles. This work improves the understanding of demulsification behaviors of magnetic demulsifiers. (C) 2014 Elsevier B.V. All rights reserved.
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