Demulsification of Oleic-Acid-Coated Magnetite Nanoparticles for Cyclohexane-in-Water Nanoemulsions

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• 作者：Jiling Liang ; Haiping Li ; Jingen Yan ; Wanguo Hou
• 刊名：Energy & Fuels
• 出版年：2014
• 出版时间：September 18, 2014
• 年：2014
• 卷：28
• 期：9
• 页码：6172-6178
• 全文大小：437K
• ISSN：1520-5029

文摘

Oleic acid (OA)-coated magnetite (Fe₃O₄) nanoparticles, denoted Fe₃O₄@OA, were synthesized by co-precipitation in the presence of varying contents of OA. The Fe₃O₄@OA nanoparticles were characterized by X-ray diffraction, transmission and scanning electron microscopies, Fourier transform infrared spectroscopy, thermogravimetric鈥揹ifferential thermogravimetric analyses, and vibrating sample magnetometry. Increasing the OA content during preparation resulted in an increase of the OA-coating amount (A_O, in units of g of OA/g of Fe₃O₄) on the Fe₃O₄ surface, before reaching an equilibrium value. The resulting magnetic nanoparticles were nearly spherical with a size of 鈭?2鈥?4 nm. OA molecules formed a single layer coating on the Fe₃O₄ surface. The A_O and area occupied by a single OA molecule at saturation coating were estimated to be 0.11 g g^鈥? (1.22 mg m^鈥?) and 0.37 nm², respectively. The Fe₃O₄@OA nanoparticles were applied in the demulsification of a cyclohexane-in-water nanoemulsion, under an external magnetic field. The effects of A_O, demulsifier dosage, pH, and electrolytes on the demulsification efficiency (E_D) were investigated. The E_D increased and then decreased with increasing A_O, which was attributed to a change in wettability of the magnetic nanoparticles. A maximum E_D of 鈭?8% was observed at a 鈭?0掳 contact angle between water and the magnetic nanoparticles. The E_D was independent of pH and electrolyte (NaCl or CaCl₂) concentration, under the studied conditions. The magnetic demulsifier exhibited excellent stability after reuse over 6 cycles. Fe₃O₄@OA nanoparticles are effective for oil鈥搘ater multiphase separation and treating oily wastewater.