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Surface and Interface Characterization of Asphaltenic Fractions Obtained with Different Alkanes: A Study by Atomic Force Microscopy and Pendant Drop Tensiometry
Energy & Fuels ( IF 5.2 ) Pub Date : 2018-10-29 00:00:00 , DOI: 10.1021/acs.energyfuels.8b02784
Iago Oliveira 1 , Larissa Gomes 1 , Elton Franceschi 1 , Gustavo Borges 1 , Juliana F. de Conto 1 , Flávio Cortinas Albuquerque 2 , Claudio Dariva 1
Affiliation  

It is recognized that asphaltenes have a tendency toward aggregation and precipitation. Even at low concentrations, they can adsorb at interfaces/surfaces where each type of interaction plays an important role in different stages of oil production. In order to evaluate the behavior of asphaltenes, it is necessary to conduct studies that allow the understanding of their chemical and physical structure, as well as to assess how they behave interfacially and superficially. By using the Pendant Drop Tensiometry and Atomic Force Microscopy techniques, the present work aims to characterize the interfacial behavior and the surface structure of two asphaltenic fractions obtained through the precipitation using n-heptane and propane as flocculants. Asphaltenic fractions were characterized by Fourier transform infrared spectroscopy, elementary analysis, gel permeation chromatography, and differential scanning calorimetry, to obtain their physicochemical characteristics. Fractions were deposited in glass substrates at different concentrations, and the contact angle between water and the substrate was determined, identifying how the different asphaltenic fractions influence the wettability of the surface, even at low concentrations. When precipitation was conducted using propane, the asphaltenic fraction showed distinct structural characteristics that were obtained by precipitation with heptane. Atomic force microscopy suggested the formation of different surface arrangements between the fractions, caused by the higher presence of resins in the fractions precipitated by propane. The pendant drop tensiometry evidenced that the asphaltenic fraction insoluble in heptane showed greater affinity to migration to the interface, producing films more resistant to the deformation, than the asphaltene fraction insoluble in propane.

中文翻译:

用不同的烷烃获得的沥青质馏分的表面和界面表征:原子力显微镜和垂坠滴定法研究

公认的是,沥青质具有聚集和沉淀的趋势。即使浓度很低,它们也可以吸附在界面/表面上,其中每种相互作用在采油的不同阶段都起着重要作用。为了评估沥青质的行为,有必要进行研究以了解其化学和物理结构,以及评估其界面和表面行为。通过使用垂坠滴定法和原子力显微镜技术,本工作旨在表征通过使用n进行沉淀获得的两个沥青质馏分的界面行为和表面结构。庚烷和丙烷作为絮凝剂。通过傅立叶变换红外光谱,元素分析,凝胶渗透色谱法和差示扫描量热法对天麻馏分进行表征,以获得其理化特性。将馏分以不同的浓度沉积在玻璃基材中,并确定水与基材之间的接触角,从而确定即使在低浓度下,不同的沥青质馏分如何影响表面的润湿性。当使用丙烷进行沉淀时,沥青质馏分显示出通过庚烷沉淀获得的独特的结构特征。原子力显微镜表明各馏分之间形成了不同的表面排列,这是由于丙烷沉淀出的馏分中树脂的含量较高所致。悬垂滴定法测定法表明,不溶于庚烷的沥青质馏分比不溶于丙烷的沥青质馏分对迁移到界面表现出更大的亲和力,从而产生了更抗变形的薄膜。
更新日期:2018-10-29
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