Ultrafiltration of natural organic matter from water by vertically aligned carbon nanotube membrane

Abstract

In this study vertically aligned carbon nanotubes (VA-CNT) was grown on anodized aluminum oxide (AAO) substrate. The synthesized AAO-CNT membrane was characterized using Raman spectroscopy, field emission scanning electron microscopy (FESEM), contact angle and BET. The pure water flux, humic acid (HA) (as representative of natural organic matters) rejection and fouling mechanism were also evaluated. The fabricated membrane has pore density of 1.3 × 1010 pores per cm2, average pore size of 20 ± 3 nm and contact angle of 85 ± 8o. A significant pure water flux of 3600 ± 100 L/m2.h was obtained at 1 bar of pressure by this membrane due to the frictionless structure of CNTs. High contact angle exhibited the hydrophobic property of the membrane. It was revealed that HA is primarily rejected by adsorption in the membrane pores due to hydrophobic interactions with HA. Flux decline occurred rapidly through both cross flow and dead end filtration of the HA. Based on the blocking laws, internal pore constriction is dominant fouling mechanism in which HA adsorbs in membrane pores results in pores blockage and flux decline.

Trihalomethane, dihaloacetonitrile, and total N-nitrosamine precursor adsorption by carbon nanotubes: the importance of surface oxides and pore volume

“…1 Additionally, incorporation of CNTs into hollow fiber membranes has been shown to increase membrane flux, fouling resistance, thermal stability, porosity, and electrochemically regenerative capability with minimal CNT leaching. [54][55][56] Fig . 4 Correlation coefficients for fluorescence intensities of WS-EFF samples in relation to TTHMFP (Fig.…”

Activated Carbon, Carbon Nanotubes and Graphene: Materials and Composites for Advanced Water Purification

“…The VA-CNT arrays are usually prepared by fabricating VA-CNTs on a solid or porous support and infiltrating a non-permeable polymer (epoxy, urethane) around the CNTs to hold them in position [142,143]. Most of the research into VA-CNT membranes has been associated with desalination, however the physical rejection of organic contaminant species has also been investigated [144,145]. The current efficiency, stability and long term performance have limited the widespread application of VA-CNT membranes, however this system may prove applicable in combination with one or more of the water purification materials discussed in this review.…”

Performance Study Of The Membrane Based Layered Double Hydroxides ‘ZnAl-Gh’ In The Purification Of Groundwater

“…The results showed that electrocoagulation process with iron and aluminum electrodes could successfully remove fluoride from the aqueous environments [6]. While other studies are focused on the methods of manufacturing aligned carbon nanotube membranes (VA-CNT) grown on an anodized aluminum oxide (AAO) substrate, show better tolerability and flexibility for the removal of other pollutants from water [7].…”