Fabrication of thin film composite poly(amide)-carbon-nanotube supported membranes for enhanced performance in osmotically driven desalination systems

Abstract

Cite this article as: Ludovic Dumée, Judy Lee, Kallista Sears, Blaise Tardy, Mikel Duke and Stephen Gray, Fabrication of thin film composite poly(amide)-carbon-nanotube supported membranes for enhanced performance in osmotically driven desalination systems, Journal of Membrane Science, http://dx.doi.org/10. 1016/j.memsci.2012.09.026 This is a PDF file of an unedited manuscript that has been accepted for publication. As a service to our customers we are providing this early version of the manuscript. The manuscript will undergo copyediting, typesetting, and review of the resulting galley proof before it is published in its final citable form. Please note that during the production process errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain. AbstractThe search for lower energy consumption desalination systems has been driving research in the past decade towards the investigation of osmotically driven membrane processes, such as forward osmosis (FO) or osmotic distillation (OD). Despite similarities with reverse osmosis (RO) membranes, thin film composite (TFC) for FO membranes require careful design to reduce salt concentration polarization formation within the large pores composing the supporting layer. An investigation of a novel, highly stable, robust support made solely of carbon nanotubes (CNTs), which could find applications in both RO and FO was undertaken. TFC membranes were fabricated by interfacially polymerizing for the first time a dense poly(amide) (PA) layer on selfsupporting bucky-papers (BPs) made of hydroxyl-functionalized entangled CNTs. These hydrophilic supports exhibited low contact angle with water (< 20 o ), high water uptake capacity (17 wt%), large porosity (> 90%), making it a promising material when compared with poly(sulfone) (PSf), the traditional polymer used to fabricate TFC membrane supports in RO. In addition, the impact of the support hydrophilicity on the stability of the interfacially polymerized film and on water adsorption was investigated by oxygen-plasma treating various potential support materials, exhibiting similar geometrical properties. The morphology and salt diffusion of both CNT BP and PSf supports were investigated, and the novel BP-PA composite membranes were found to be superior to commercially available TFC membranes. KeywordsCarbon nanotube bucky-paper; forward osmosis; thin film composite membrane; poly(amide) interfacial polymerization 3

Influence of the process parameters on hollow fiber-forward osmosis membrane performances

“…Irregular shaped pores are changed to uniform size pores which allow water molecules easily pass through the membrane and thus high fluxes are obtained. We conclude that with the new pore shape arrangements, the pore structures also becomes align with each other, symmetrical throughout the membrane depth and thus resembles uniform structures close to the CNT membrane structures which have shown higher water flux [47,65]. It was observed that at there is a particular set of FS and DS flow rate which help get highest flux through the FO membrane.…”

“…Both these follow the same permeation rate and are readily rationalized by the filtration-type mechanism or a pore-flow membrane. PSF support layerusually showed pore sizes of 20-25 nm [65]. Due to the large pore size of membrane SL, it is suspected that the PSF support layer don't offer any molecular resistance to salt permeation and direct salt diffusion occur.…”

Recent advancements in forward osmosis desalination: A review

“…Tang et al have modeled a similar double-skinned FO membrane and have observed that the best double-skinned FO membrane should maintain a mass transfer coefficient that is high for the porous support, have a brackish water RO type draw skin, a feed skin with low rejection NF [142]. Su et al have also fabricated double-skinned CA hollow fibers consisting of an inner or outer selective layer by employing different phase inversion rates and extent of thermal annealing at Electro-spinning, phase separation and IP [135] 2012 TFC PA Super porous CNT non-woven Bucky-paper (BP) support, PA active layer Plasma treatment of CNT BPs support and IP [136] 2012 Dual layer hollow fiber NF PES inner support layer and PAI active layer post-treated by PEI Dry-jet wet spinning, one-step coextrusion, multi-layer polyelectrolyte depositions [137] 2013 Thin-film inorganic (TFI) Stainless steel mesh (SSM) substrate, micro-porous silica xerogels active layer Dip-coating and calcining for 4 h at 500°C in nitrogen followed by cooling to 25°C [118] 2014 Thin-film nanocomposite (TFN)…”

Forward Osmosis in Wastewater Treatment Processes

“…62 Also bucky papers made from Carbon Nanotubes (CNTs) and nanofiber mats formed from electrospun fibres have been suggested as good FO membrane support due to high porosity and tensile strength. 68,69 Structurally it has been argued that an open šfinger' like structure of the support is to be favoured over a more dense šsponge' like structure. 70 However a more open structure is also mechanically weaker and a more dense structure also may have a higher ICP.…”