Xu Haiyan, Wang Jinqing, Yang Xiaohan, Ning Liping
College of Forestry, Sichuan Agricultural University, Chengdu 611130, China.
Wood Industry and Furniture Engineering Key Laboratory of Sichuan Provincial Department of Education, Chengdu 611130, China.
ACS Appl Mater Interfaces. 2021 Feb 10;13(5):6748-6757. doi: 10.1021/acsami.0c18115. Epub 2021 Jan 29.
In the present work, an amphiphilic and magnetically recyclable graphene oxide (MR-GO) demulsifier was devised and synthesized by graft of magnetic nanoparticles (FeO@SiO-APTES) and ethylenediamine on the GO surface. The wettability and surface charges of MR-GO under various pH conditions can be regulated via adjusting the contents and species of surface functional groups (such as amino, carboxyl, and hydroxyl). In the demulsificaition test, MR-GO displayed favorable demulsification performance for crude oil-in-water (O/W) emulsion under pH of 2.0-10.0, thusly greatly improving the application scope of common demulsifier. The optimal dosage of MR-GO was 200 mg/L and the demulsification efficiency attained a maximum value of 99.7% for crude O/W emulsion with pH of 6.0. What's more, owing to its magnetic response performance, the MR-GO can be reused and the demulsification efficiency remained above 91.0% after six cycles. Based on the strong interfacial activity, MR-GO can arrive to the crude oil-water interface. With the synergy effects of interfacial adsorption (π-π/n-π) interactions and electrostatic attraction of demulsifier and interfacial films, and the aid of external mechanical forces, the interfacial films stabilized the emulsion were disrupted. Therefore, the oil droplets coated on the water droplets were gathered rapidly to form oily flocs and then migrated to the water surface to accomplish the demulsification of crude O/W emulsion.
在本工作中，通过在氧化石墨烯（GO）表面接枝磁性纳米颗粒（Fe₃O₄@SiO₂-APTES）和乙二胺，设计并合成了一种两亲性且可磁回收的氧化石墨烯（MR-GO）破乳剂。通过调节表面官能团（如氨基、羧基和羟基）的含量和种类，可以调控不同pH条件下MR-GO的润湿性和表面电荷。在破乳试验中，MR-GO在pH为2.0 - 10.0的条件下对水包油（O/W）型原油乳液表现出良好的破乳性能，从而大大拓宽了普通破乳剂的应用范围。MR-GO的最佳用量为200 mg/L，对于pH为6.0的原油O/W乳液，破乳效率达到最大值99.7%。此外，由于其磁响应性能，MR-GO可以重复使用，经过六个循环后破乳效率仍保持在91.0%以上。基于其强大的界面活性，MR-GO能够到达原油 - 水界面。在破乳剂与界面膜的界面吸附（π-π/n-π）相互作用和静电吸引的协同作用以及外部机械力的辅助下，稳定乳液的界面膜被破坏。因此，包裹在水滴上的油滴迅速聚集形成油絮凝物，然后迁移到水面完成原油O/W乳液的破乳。
