Multi‐walled Carbon Nanotubes Grafted by Polyvinyl Alcohol and Its Demulsification Performance in Oily Wastewater

• Published in: ChemistrySelect (Weinheim) Vol. 5; no. 26; pp. 7895 - 7900
• Main Authors: Jiang, Xia, Ye, Fan, Zheng, Lihua, Mi, Yuanzhu, Zhang, Zejun, Yuan, Huaikui, Liu, Wangfu, Kuang, Jiazhe, Luo, Yue
• Format: Journal Article
• Language: English
• Published: 15.07.2020
• Subjects: CNTs@PVA; Demulsification; Interfacial activity; Oily wastewater
• ISSN: 2365-6549; 2365-6549
• DOI: 10.1002/slct.202001792

Multi‐walled carbon nanotubes grafted by polyvinyl alcohol (CNTs@PVA) were synthesized via free radical reaction process under ultrasonic condition and used in oily wastewater for the demulsification. FT‐IR, UV‐Vis, SEM and TGA were employed to characterize the as‐prepared CNTs@PVA. The demulsification performance in oily wastewater was estimated by bottle test. When the CNTs@PVA dosage was 80 mg/L, the light transmittance of separated water and the oil removal rate of the emulsions at room temperature for 30 min could reach 84.2% and 97.1%, respectively. In addition, the demulsification mechanism was systemically investigated by dynamic interfacial tension, interfacial activity, wettability, zeta potential and optical microscope. It suggested that PVA could tune the wettability of multi‐walled carbon nanotubes by the surface modification. The change of the wettability is beneficial to the migration of CNTs@PVA to the oil‐water interface, and accelerate the coalescence of oil droplets. The current finding provides a new non‐toxic and high efficiency demulsifier for the oily wastewater. The CNTs@PVA composite exhibits an amphiphilic properties. It can quickly migrate to the oil‐water interface and be coequally wetted by the oil and water, the hydrophilic end enters the water phase and the hydrophobic end enters the oil phase. It will reduce the interfacial tension, replace the natural surfactant and cause the fracture of the interfacial film, which promotes the flocculation and coalescence of the oil droplets.