Self‐supported single‐wall carbon nanotube buckypaper membranes applied to air and water filtration

Abstract

Background: This work addresses the use of self-supported single-wall carbon nanotube (SWCNT) buckypapers as filters or membranes to treat air or water streams to reduce the concentration of pollutants.Results: The fabrication of the buckypapers was carried out by a facile filtration method. The performance of the buckypaper as an air filter was tested with a NaCl aerosol obtaining a permeance of 241 m 3 m −2 h −1 bar −1 and a filtration efficiency of 99.9991%. The performance of the buckypaper as a water ultrafiltration (UF) membrane was studied separating ZIF-8 nanoparticles of 30, 50 and 120 nm in diameter, achieving a permeance of 124 L•m −2 h −1 bar −1 and a rejection of 99.99%.Conclusions: A simple technique is described for the rapid fabrication of self-supported SWCNT buckypaper membranes with a filtration method resulting in an excellent performance in both air and water filtration. In addition, because of the acquired control of ZIF-8 crystallization, particles of different sizes of this material were synthesized ad hoc to serve as a reference solute of UF separation.

Double-Layered Pebax® 3533/ZIF-8 Membranes with Single-Walled Carbon Nanotube Buckypapers as Support for Gas Separation

“…However, a greater loss of solvents (weight loss below 200 °C) was observed in the membranes with Pebax ® . Regarding the TGA of the SWCNTs, their degradation does not start until 550 °C having at 700 °C a remaining weight; this thermal stability has already been observed previously [ 9 ]. In the membrane, it can also be seen that an incomplete degradation was observed at 700 °C due to the presence of SWCNTs and ZnO formation from ZIF decomposition.…”

“…Single-walled carbon nanotubes (SWCNT, 1.2–2 nm) ≥93% carbon content and non-ionic surfactant Triton™ X-100 were purchased from Sigma-Aldrich. SWCNTs were used as received; additional characterization of them can be found in our previous publication [ 9 ]. 2-propanol (IPA, HPLC grade, ≥99.9%) and methanol (HPLC grade, ≥99.9%) were obtained at Panreac Applichem.…”

“…By adapting a previously published technique, free-standing SWCNT films were prepared using a vacuum filtering process [ 9 , 24 , 25 , 26 ]. Typically, 10 mg of SWCNT was dispersed in 60 mL of distilled water with 1 wt % of Triton X-100 surfactant using an ultrasound probe sonicator (Sonics Materials VC-750–220, 750 W, 20 kHz) for 1 h. The sonicated suspension was then filtered through a porous Nylon™ filter housed in a glass filtration funnel with a diameter of 47 mm and washed with a 1:1 ( v / v ) acetone:2-propanol solution [ 24 ].…”

“…An ideal membrane for gas separation should be composed of a selective skin layer exceeding the Robeson trade-off relation between selectivity and permeability [ 7 ], as thin as possible with the objective of achieving high permeance (permeability divided by membrane thickness) but mechanically robust [ 8 , 9 ].…”

“…Carbon nanotubes are promising materials for gas and water filtration based on membranes due to their high specific porosity and surface area, hydrophobicity, mechanical strength and potential functionalization [ 9 , 19 , 20 , 21 ]. In addition, they are commercially available.…”