Department of Mining and Petroleum Engineering, Faculty of Engineering, Chiang Mai University, Chiang Mai 50200, Thailand.
School of Chemical and Process Engineering, University of Leeds, Leeds LS2 9JT, United Kingdom.
Langmuir. 2023 Feb 21;39(7):2483-2490. doi: 10.1021/acs.langmuir.2c01413. Epub 2023 Feb 8.
The interfacial activity of poly(-isopropylacrylamide) (pNIPAM) nanoparticles in the absence and presence of an anionic surfactant (sodium dodecyl sulfate, SDS) was studied at a crude oil-water interface. Both species are interfacially active and can lower the interfacial tension, but when mixed together, the interfacial composition was found to depend on the aging time and total component concentration. With the total component concentration less than 0.005 wt %, the reduced interfacial tension by pNIPAM was greater than SDS; thus, pNIPAM has a greater affinity to partition at the crude oil-water interface. However, the lower molecular weight (smaller molecule) of SDS compared to pNIPAM meant that it rapidly partitioned at the oil-water interface. When mixed, the interfacial composition was more SDS-like for low total component concentrations (≤ 0.001 wt %), while above, the interfacial composition was more pNIPAM-like, similar to the single component response. Applying a weighted arithmetic mean approach, the surface-active contribution (%) could be approximated for each component, pNIPAM and SDS. Even though SDS rapidly partitioned at the oil-water interface, it was shown to be displaced by the pNIPAM nanoparticles, and for the highest total component concentration, pNIPAM nanoparticles were predominantly contributing to the reduced oil-water interfacial tension. These findings have implications for the design and performance of fluids that are used to enhance crude oil production from reservoirs, particularly highlighting the aging time and component concentration effects to modify interfacial tensions.
在不存在和存在阴离子表面活性剂（十二烷基硫酸钠，SDS）的情况下，研究了聚（异丙基丙烯酰胺）（pNIPAM）纳米颗粒在油水界面的界面活性。这两种物质都具有界面活性，可以降低界面张力，但当混合在一起时，发现界面组成取决于老化时间和总组分浓度。当总组分浓度小于 0.005wt%时，pNIPAM 降低界面张力的效果大于 SDS；因此，pNIPAM 更倾向于分配到油水界面。然而，与 pNIPAM 相比，SDS 的分子量较低（分子较小），意味着它可以迅速分配到油水界面。当混合时，对于低总组分浓度（≤0.001wt%），界面组成更类似于 SDS，而在以上浓度时，界面组成更类似于 pNIPAM，类似于单一成分的响应。应用加权算术平均值方法，可以近似估算每个成分（pNIPAM 和 SDS）的表面活性贡献（%）。尽管 SDS 迅速分配到油水界面，但它被 pNIPAM 纳米颗粒取代，对于最高总组分浓度，pNIPAM 纳米颗粒主要有助于降低油水界面张力。这些发现对于设计和性能用于从储层中增强原油生产的流体具有重要意义，特别强调了老化时间和组分浓度对改变界面张力的影响。
