Zaib Qammer, Adeyemi Idowu, Warsinger David M, AlNashef Inas M
Department of Civil and Environmental Engineering, University of Ulsan, Ulsan, South Korea.
Department of Chemical Engineering, Khalifa University of Science and Technology, Abu Dhabi, United Arab Emirates.
Front Chem. 2020 Sep 17;8:808. doi: 10.3389/fchem.2020.00808. eCollection 2020.
Deep Eutectic Solvents (DESs) are emerging as a promising medium for many chemical processes. They can be used to observe specific properties required for nanomaterials' applications. Controlled CO adsorption requires disaggregation of carbon nanotubes into smaller bundles which can be accomplished by dispersing them in aqueous DES system. In this study, response surface methodology (RSM) was adopted to examine the impacts of three important factors on the dispersion of single walled carbon nanotubes (SWNTs) in Choline Chloride-Glycerol (ChCl-Gly) DES; (i) ChCl-Gly (mass% in water), (ii) sonication energy input (J/mL), and (iii) SWNTs' concentration (mg/L). The net negative surface charge of ChCl-Gly, a "green solvent," provided superior dispersion of inherently negatively charged SWNTs in water via electrostatic repulsion. The impacts of the dispersion factors were quantified by the average aggregate diameter (nm) and polydispersity (polydispersity index, PDI) of SWNTs in aqueous-DES systems. Models were developed, experimentally verified, and statistically validated to map the impacts of these factors and to obtain optimized dispersions. The optimized dispersions, characterized by the small (<100 nm) and uniform (<0.1 PDI) SWNTs' aggregates, were achieved at lower sonication energy costs which can have promising implications across many nano-manufacturing fields. The dispersion/aggregation mechanism was proposed using COSMO-RS (based on equilibrium thermodynamics and quantum chemistry) modeling of ChCl-Gly and zeta potential measurements of SWNTs. This understanding will help create optimally sustainable and economically feasible DES-nanomaterial dispersions.
深共熔溶剂（DESs）正成为许多化学过程中一种很有前景的介质。它们可用于观察纳米材料应用所需的特定性能。可控的CO吸附需要将碳纳米管解聚成更小的管束，这可以通过将它们分散在水性DES体系中来实现。在本研究中，采用响应面方法（RSM）来研究三个重要因素对单壁碳纳米管（SWNTs）在氯化胆碱 - 甘油（ChCl - Gly）DES中的分散的影响；（i）ChCl - Gly（在水中的质量百分比），（ii）超声能量输入（J/mL），以及（iii）SWNTs的浓度（mg/L）。“绿色溶剂”ChCl - Gly的净负表面电荷通过静电排斥作用，使本质上带负电荷的SWNTs在水中具有优异的分散性。分散因素的影响通过SWNTs在水性DES体系中的平均聚集体直径（nm）和多分散性（多分散指数，PDI）来量化。开发了模型，进行了实验验证和统计验证，以描绘这些因素的影响并获得优化的分散体。以小（<100 nm）且均匀（<0.1 PDI）的SWNTs聚集体为特征的优化分散体，在较低的超声能量成本下得以实现，这在许多纳米制造领域可能具有广阔的应用前景。利用ChCl - Gly的COSMO - RS（基于平衡热力学和量子化学）模型以及SWNTs的zeta电位测量结果，提出了分散/聚集机制。这种认识将有助于创建最优的可持续且经济可行的DES - 纳米材料分散体。
