Svalova Aleksandra, Walshaw David, Lee Clement, Demyanov Vasily, Parker Nicholas G, Povey Megan J, Abbott Geoffrey D
School of Mathematics, Statistics and Physics, Newcastle University, Newcastle upon Tyne, NE1 7RU, UK.
Department of Mathematics and Statistics, Lancaster University, Lancaster, LA1 4YF, UK.
Sci Rep. 2021 Mar 23;11(1):6698. doi: 10.1038/s41598-021-85926-8.
Bayesian inference and ultrasonic velocity have been used to estimate the self-association concentration of the asphaltenes in toluene using a changepoint regression model. The estimated values agree with the literature information and indicate that a lower abundance of the longer side-chains can cause an earlier onset of asphaltene self-association. Asphaltenes constitute the heaviest and most complicated fraction of crude petroleum and include a surface-active sub-fraction. When present above a critical concentration in pure solvent, asphaltene "monomers" self-associate and form nanoaggregates. Asphaltene nanoaggregates are thought to play a significant role during the remediation of petroleum spills and seeps. When mixed with water, petroleum becomes expensive to remove from the water column by conventional methods. The main reason of this difficulty is the presence of highly surface-active asphaltenes in petroleum. The nanoaggregates are thought to surround the water droplets, making the water-in-oil emulsions extremely stable. Due to their molecular complexity, modelling the self-association of the asphaltenes can be a very computationally-intensive task and has mostly been approached by molecular dynamic simulations. Our approach allows the use of literature and experimental data to estimate the nanoaggregation and its credible intervals. It has a low computational cost and can also be used for other analytical/experimental methods probing a changepoint in the molecular association behaviour.
贝叶斯推理和超声波速度已被用于通过变点回归模型估计沥青质在甲苯中的自缔合浓度。估计值与文献信息相符，表明较长侧链的丰度较低会导致沥青质自缔合更早开始。沥青质是原油中最重且最复杂的部分，包括一个表面活性亚组分。当在纯溶剂中高于临界浓度存在时，沥青质“单体”会自缔合并形成纳米聚集体。沥青质纳米聚集体被认为在石油泄漏和渗漏的修复过程中起重要作用。当与水混合时，通过传统方法从水柱中去除石油成本很高。造成这种困难的主要原因是石油中存在高度表面活性的沥青质。纳米聚集体被认为会包围水滴，使油包水乳液极其稳定。由于其分子复杂性，模拟沥青质的自缔合可能是一项计算量极大的任务，并且大多通过分子动力学模拟来解决。我们的方法允许使用文献和实验数据来估计纳米聚集及其可信区间。它具有较低的计算成本，还可用于探测分子缔合行为中变点的其他分析/实验方法。
