A superhydrophobic carbon nanotube hollow fiber membrane for electrically self-heating membrane distillation

Abstract

Self-heating membrane distillation has been considered as an alternative technology to alleviate water crisis, while the unsatisfactory energy efficiency and distillate flux limit the practical application. Herein, an all-in-one conductive hollow fiber membrane without supporting layer was fabricated, in which carbon nanotube (CNT) guaranteed the rapid electro-thermal conversion and polydimethylsiloxane (PDMS) endowed the composite membrane with superhydrophobicity to enhance membrane stability. The narrow channel of the hollow fiber membrane encircled the feed solution in a localized space to achieve efficient vaporization, which was benefit for both high higher distillate flux and low energy requirement. As a result, the CNT/PDMS hollow fiber membrane obtained a high distillate flux of 24.27 ± 0.89 kg m−2 h−1 and salt rejection rate > 99.9 % under 2.5 W input power with a flow rate of 12.81 mm s−1. Meanwhile, this membrane displayed a superior salt-resistance with increasing of the feed solution concentration from 10 g L−1 to 100 g L−1. For actual seawater desalination, the concentration of representative ions in collected water met the requirement standard of soft drinking water, indicating a great feasibility in practical application. Thus, this energy-efficient hollow fiber membrane provides a promising avenue to fabricate high-performance self-heating membrane for membrane distillation.