Recyclable amine-functionalized carbon nanotubes for the separation of oily wastewater

• Published in: Chemosphere (Oxford) Vol. 288; no. Pt 2; p. 132571
• Main Authors: Ye, Fan, Wang, Gang, Ao, Yiling, Shen, Liwei, Yang, Ying, Feng, Xuening, Zhang, Zejun, Yuan, Huaikui, Mi, Yuanzhu, Yan, Xuemin
• Format: Journal Article
• Language: English
• Published: England Elsevier Ltd 01.02.2022
• Subjects: Amines; Demulsification; Mechanism; Nanotubes, Carbon; Recycle; Recycling; Waste Water; Mechanism; Recycle; Demulsification
• ISSN: 0045-6535; 1879-1298
• DOI: 10.1016/j.chemosphere.2021.132571

In this work, a CNTs-NH2 demulsifier was prepared by grafting ethylenediamine on the surface of carbon nanotubes to break oily wastewater. The physicochemical and interfacial properties of CNTs-NH2 were characterized and analyzed. It showed that CNTs-NH2 had an eminent amphipathicity and high interfacial activity, which allows it to sharply migrates to the interface and effectively interacts with interfacial film by the combined action of π-π interaction and electrostatic attraction. The demulsification tests exhibited that CNTs-NH2 could effectively remove emulsified oil from the oily wastewater. It could be used at acidic and neutral conditions, and high salinity. Moreover, it could be recycled and still maintained its interfacial activity, thusly vastly enhancing the application scope. The light transmittance was up to 88.1% and the corresponding oil removal rate was 99.2% with 100 mg/L of CNTs-NH2 for 30 min. The oil removal rate of CNTs-NH2 remained above 97.8% after 6 cycles. This work provides a deep understanding on the design of demulsifier and its demulsification mechanism. [Display omitted] •CNTs-NH2 had an eminent amphipathicity and high interfacial activity.•CNTs-NH2 can be reused 6 cycles without significant decline of DE.•CNTs-NH2 can be used at acidic and neutral conditions, and high salinity.•Synergistic effect of π-π interaction and electrostatic attraction induces demulsification.