Carbon nanotubes for desalination: Performance evaluation and current hurdles

The fast-evolving world of nanotechnology captivates researchers in the state-of-the-art water desalination technologies. Rapid development and advancement have been reflected by a drastically increasing number of scientific investigation on the manipulation of nanomaterials in various desalination technologies. With demand rising in worldwide, the revolution of desalination technology using CNT materials to mitigate few raised over concerns, particularly energy issues, seems a viable option. In this context, this review article intends to provide an in-depth insight on the utilization of CNTs to heighten the performance of the available seawater and brackish water desalination in a holistic manner. The transport properties and chemical functionalities of this novel material to potentially facilitate excellent flux of water transport and salt rejection are outlined. Based on the computational and experimental work done over the past decade, a detailed description on the current knowledge relevant to the exploitation of CNTs in desalination has been highlighted. The current hurdles and future challenges related to this technology are then addressed. With novel properties come new opportunities for technological and commercial development. The applications of CNTs in desalination have been demonstrated and it is anticipated that applying CNTs in desalination holds very promising future prospects and will therefore lead the future direction of the realm. © 2012 Elsevier B.V. All rights reserved.

This review provides an overview of application of CNT materials as the future research strategies and directions to meet the challenges that are facing the worldwide application of desalination technologies. In the past decades, desalination and wastewater reclamation processes have been studied extensively to mitigate the water crisis. A suite of new technologies is realized by recent progress in the rational design and manipulation of nanomaterials. The CNT-incorporated desalination materials deserve greater research efforts. Remarkable accomplishment of CNT-based desalination leads to greener process which could make the desalination economically competitive to provide potable water where it is needed. The higher flux and salt rejection have practical impacts as they eventually lead to significantly higher efficiency processes, thus requiring less membrane materials and energy per unit of water desalined. It is anticipated that the emergence of CNTs could revolutionize the desalination technology sector by providing higher throughput and more effective separation characteristics, without imparting significant cost to the overall desalination system. Tremendous interest in CNT-based desalination is evidenced from the plethora of studies, in experimental and theoretical means, that have implied the extraordinarily high water flux while exhibiting promising salt rejection properties. In broader terms, the involvement of CNTs in the desalination devices can be done through the preparation of free standing aligned CNT membrane as well as the CNT incorporated mixed matrix membrane. The development of such membranes is still at the premature stage and many problems are yet to be resolved while more challenges are awaiting. On the other hand, in nonmembrane desalination technologies, CNTs have been widely utilized as the electrode materials. Up to date, more experimental studies have been reported on the potential application of CNTs to enhance the efficiency of electrochemical-based desalination primarily due to the simplicity of electrode preparation. Despite the relatively short period of its research history in both scientific and technological aspects, the desalination technology based on CNTs is now emerging from the laboratory or pilot scale to become a valid and reliable commercial technology. But making the leap to commercial applications is complicated and is still a distant goal for this emerging approach. Since the commercialization of CNT-incorporated desalination technology is still at its premature stage, more scientific and technical inputs are crucial to explore more possibilities and potentials that lie behind. Also, with the stimulating community's fascination and further impressive progresses done on CNT material for desalination application, it has no doubt that CNT materials will find their role in the future direction of desalination technology to allow for greater flexibility and broader perspective in addressing the critical water issues. Acknowledgment The authors would like to express gratitude to the Ministry of Science, Technology and Innovation Malaysia for the financial support on the work undertaken in this research center.