Jamaluddin Nur Amirah, Mohamed Azmi, Abu Bakar Suriani, Ardyani Tretya, Sagisaka Masanobu, Suhara Shota, Hafiz Mamat Mohamad, Ahmad Mohd Khairul, King Stephen M, Rogers Sarah E, Eastoe Julian
Department of Chemistry, Faculty of Science and Mathematics, Universiti Pendidikan Sultan Idris, 35900 Tanjong Malim, Perak, Malaysia.
Phys Chem Chem Phys. 2020 Jun 14;22(22):12732-12744. doi: 10.1039/d0cp01243b. Epub 2020 May 28.
The generation of surfactant-assisted exfoliated graphene oxide (sEGO) by electrochemical exfoliation is influenced by the presence of surfactants, and in particular the hydrophobic tail molecular-architecture. Increasing surfactant chain branching may improve the affinity for the graphite surfaces to provide enhanced intersheet separation and stabilisation of exfoliated sheets. The resulting sEGO composites can be readily used to remove of a model pollutant, the dye, methylene blue (MB), from aqueous solutions by providing abundant sites for dye adsorption. This article explores relationships between surfactant structure and the performance of sEGO for MB adsorption. Double-branched and highly branched triple-chain graphene-compatible surfactants were successfully synthesised and characterised by H NMR spectroscopy. These surfactants were used to produce sEGO via electrochemical exfoliation of graphite, and the sEGOs generated were further utilised in batch adsorption studies of MB from aqueous solutions. The properties of these synthesised surfactants were compared with those of a common single-chain standard surfactant, sodium dodecyl-sulfate (SDS). The structural morphology of sEGO was assessed using Raman spectroscopy and field emission scanning electron microscopy (FESEM). To reveal the links between the hydrophobic chain structure and the sEGO adsorption capacity, UV-visible spectroscopy, zeta potential, and air-water (a/w) surface tension measurements were conducted. The aggregation behaviour of the surfactants was studied using small-angle neutron scattering (SANS). The highly branched triple-chain surfactant sodium 1,4-bis(neopentyloxy)-3-(neopentylcarbonyl)-1,4-dioxobutane-2-sulfonate (TC14) displayed enhanced exfoliating efficiency compared to those of the single-and double-chain surfactants, leading to ∼83% MB removal. The findings suggest that highly branched triple-chain surfactants are able to offer more adsorption sites, by expanding the sEGO interlayer gap for MB adsorption, compared to standard single-chain surfactants.
通过电化学剥离法生成表面活性剂辅助剥离氧化石墨烯（sEGO）受到表面活性剂的存在，特别是疏水尾部分子结构的影响。增加表面活性剂链的支化度可能会提高对石墨表面的亲和力，从而增强片层间的分离并稳定剥离后的片层。所得的sEGO复合材料可通过提供丰富的染料吸附位点，轻松用于从水溶液中去除模型污染物——染料亚甲基蓝（MB）。本文探讨了表面活性剂结构与sEGO对MB吸附性能之间的关系。成功合成了双支化和高度支化的三链石墨烯兼容表面活性剂，并通过核磁共振氢谱（H NMR）进行了表征。这些表面活性剂用于通过石墨的电化学剥离制备sEGO，所生成的sEGO进一步用于从水溶液中对MB的批量吸附研究。将这些合成表面活性剂的性能与常见的单链标准表面活性剂十二烷基硫酸钠（SDS）的性能进行了比较。使用拉曼光谱和场发射扫描电子显微镜（FESEM）评估了sEGO的结构形态。为了揭示疏水链结构与sEGO吸附容量之间的联系，进行了紫外可见光谱、zeta电位和空气-水（a/w）表面张力测量。使用小角中子散射（SANS）研究了表面活性剂的聚集行为。与单链和双链表面活性剂相比，高度支化的三链表面活性剂1,4-双（新戊氧基）-3-（新戊酰基）-1,4-二氧代丁烷-2-磺酸钠（TC14）显示出更高的剥离效率，导致约83%的MB去除率。研究结果表明，与标准单链表面活性剂相比，高度支化的三链表面活性剂能够通过扩大sEGO层间间隙以吸附MB，提供更多的吸附位点。
