Abstract A novel Janus composite membrane via hydrophilization of conventional PVDF hydrophobic membrane based on multiwall carbon nanotube (CNT) functionalized with carboxylic groups was investigated for use in membrane distillation. The modified membrane exhibited in-air water hydrophilicity and underwater oleophobicity. Interestingly, despite of the smaller effective pore size than that of the virgin membrane, the vapor flux was not compromised in the modified membrane, while a slight flux enhancement was observed, probably due to the high water permeability and heat conduction of the CNT layer, as suggested by the mass-heat transfer studies. Moreover, antifouling properties of the modified membrane were noted for treating a hexadecane emulsion of 1000 mg/L. The variation in the decrease in flux and the increase in conductivity was in line with force analysis between membrane and oil droplet, and the superior performance of modified membrane to the virgin membrane may be attributed to the good hydrophilicity of the functionalized CNT layer. Our results confirmed the hypothesis that CNT with high mass-heat transfer capability, homogeneously coated in a hydrophilic layer, may be promising candidate for fabricating a new-generation of fouling-resistant Janus membrane to treat oily wastewater.

中文翻译：

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用于直接接触膜蒸馏的抗油污碳纳米管基Janus复合膜

摘要 研究了基于羧基官能化的多壁碳纳米管 (CNT) 的传统 PVDF 疏水膜的亲水化新型 Janus 复合膜，用于膜蒸馏。改性膜表现出空气中亲水性和水下疏油性。有趣的是，尽管有效孔径比原始膜小，但改性膜的蒸汽通量并未受到影响，而观察到通量略有增加，这可能是由于 CNT 层的高透水性和热传导性，正如传质研究所建议的那样。此外，改性膜的防污性能在处理 1000 mg/L 的十六烷乳液时被注意到。通量降低和电导率增加的变化与膜和油滴之间的力分析一致，改性膜优于原始膜的性能可能归因于功能化CNT层的良好亲水性。我们的研究结果证实了这样一个假设，即具有高传质能力、均匀涂覆在亲水层中的 CNT 可能是制造新一代抗污染 Janus 膜以处理含油废水的有希望的候选者。