【摘要】：采用分子動(dòng)力學(xué)模擬研究了以十二烷基苯磺酸鈉(SDBS)為代表的陰離子型表面活性劑,以十二烷基三甲基溴化銨(DTAB)為代表的陽離子型表面活性劑,以壬基酚聚氧乙烯醚(NPE)為代表的非離子型表面活性劑,以十二烷基二甲基甜菜堿(Betaine)為代表的兩性表面活性劑及空白實(shí)驗(yàn).模擬了表面活性劑在油水界面上的行為,考察了表面活性劑分子與石油分子之間的徑向分布函數(shù)(RDF)、石油分子在豎直方向的均方位移(MSD)、油水界面張力(IFT)、石油層與巖石層之間的相互作用能、石油層的相對(duì)濃度在豎直方向的分布及石油分子質(zhì)心位置隨模擬時(shí)間的變化關(guān)系等,討論了不同表面活性劑的洗油性能.結(jié)果表明:(1)SDBS,NPE和Betaine分子初始狀態(tài)下呈近似的規(guī)律排列,非極性端部分插入油相中,極性端延伸進(jìn)入水相中;隨后表面活性劑的極性端表現(xiàn)出聚集趨勢(shì),逐漸形成一個(gè)外部親油內(nèi)部親水的一個(gè)膠束狀粒子,粒子隨模擬的進(jìn)行逐漸融入到油層當(dāng)中;DTAB從開始的近似規(guī)則排列逐漸變?yōu)闊o規(guī)排列,但是始終保持親油端插入到油相中,親水端位于油水界面上.(2)表面活性劑分子與石油分子之間的相互作用強(qiáng)弱順序?yàn)锽etaine≈DTABSDBSNPE.(3)由質(zhì)心高度和動(dòng)力過程中的圖像截圖分析,表面活性劑洗油效果的順序?yàn)锽etaineSDBSNPEDTABNone.模擬結(jié)果與實(shí)際的驅(qū)油結(jié)果一致,從分子層面上解釋了不同表面活性劑洗油的規(guī)律.
[Abstract]:The anion surfactant represented by sodium dodecylbenzene sulfonate (SDBS) and the cationic surfactant represented by dodecyl trimethylammonium bromide (DTAB) were studied by molecular dynamics simulation. Non-ionic surfactant represented by nonylphenol polyoxyethylene ether (NPE), amphoteric surfactant represented by dodecyl dimethyl betaine (Betaine) and blank experiment. The behavior of surfactants at the oil-water interface was simulated. The radial distribution function between surfactant molecules and petroleum molecules was studied. The interaction energy of (RDF), oil molecules in vertical mean square displacement (MSD), oil-water interfacial tension (IFT), oil layer and lithosphere was investigated. The distribution of the relative concentration in the vertical direction and the relationship between the position of the molecular mass center and the simulation time were discussed. The oil washing performance of different surfactants was discussed. The results show that: (1) at the initial state of SDBS,NPE and Betaine molecules are arranged approximately, the non-polar end is partially inserted into the oil phase, the polar end extends into the water phase, and the polar end of the surfactant shows a tendency of aggregation. A micellar particle gradually formed, which was hydrophilic and hydrophilic inside the outer oil. The particles were gradually integrated into the reservoir with the simulation, and the DTAB gradually changed from approximate regular arrangement to random arrangement, but the oil-friendly end was always inserted into the oil phase. The hydrophilic end is located at the oil-water interface. (2) the order of interaction between surfactant molecules and petroleum molecules is Betaine 鈮，

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