Abstract
In this paper, vertically aligned carbon nanotube (VACNT) membranes of different densities are developed and their performances are investigated. VACNT arrays of densities 5 × 109, 1010, 5 × 1010 and 1011 tubes cm−2, are initially grown on 1 cm × 1 cm silicon substrates using chemical vapour deposition. A VACNT membrane is realised by attaching a 300 μm-thick 1 cm × 1 cm VACNT array on silicon to a 4″ glass substrate, applying polydimethylsiloxane (PDMS) through spin coating to fill the gaps between the VACNTs, and using a microtome to slice the VACNT–PDMS composite into 25-μm-thick membranes. Experimental results show that the permeability of the developed VACNT membranes increases with the density of the VACNTs, while the salt rejection is almost independent of the VACNT density. The best measured permeance is attained with a VACNT membrane having a CNT density of 1011 tubes cm−2 is 1203 LMH at 1 bar.
Highlights
Within the last one and half decades, many researchers have worked on different types of CNT based membranes
The properties of the fabricated Vertically aligned carbon nanotubes (VACNT) membranes were compared with the properties of CNT membranes developed by other groups, which were mainly used for gas filtration (Futaba et al 2006; Zhao et al 2009b; Ge et al 2012; Skoulidas et al 2002; Ackerman et al 2003; Kumar et al 2012; Gilani et al 2013; Majumder et al 2011; Krishnakumar et al 2012; Mi et al 2007)
It is important to note that various VACNT membranes of thicknesses 22, 25 and 30 μm were developed, and results show that the impact of the VACNT membrane thickness on the membrane’s performance is negligible
Summary
Within the last one and half decades, many researchers have worked on different types of CNT based membranes. The permeance and salt rejection properties of four membranes of different VACNT densities are experimentally investigated. After spin coating the PDMS onto the VACNT wafer, VACNT membranes of different thicknesses were sliced and detached from the Si/glass supports. The fabrication method is summarised as follows: VACNTs on silicon wafers of different VACNT densities were purchased from DK Nanomaterials Co. Ltd (China). The permeate flux for each membrane was measured under different vacuum pressures in order to check the consistency and reproducible fabrication of the membranes. The salt rejection was calculated from the measured flux, for all developed membrane samples using the following equation (Vatanpour et al 2011)
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
