Thin-Film Nanocomposite Forward-Osmosis Membranes on Hydrophilic Microfiltration Support with an Intermediate Layer of Graphene Oxide and Multiwall Carbon Nanotube

Abstract

A novel thin-film nanocomposite forward-osmosis (FO) membrane was fabricated on hydrophilic nylon microfiltration (MF) support by interfacial polymerization with the assistance of an intermediate layer of graphene oxide and multiwall carbon nanotube (GO/MWCNT). The chemical composition, structure, and surface properties of the synthesized FO membranes were studied using various characterization methods. It was found that the GO/MWCNT composite layer not only provided ultrafast nanochannels for water transport but also reduced the thickness of the polyamide layer by up to 60%. As a result, the novel FO membrane exhibited a higher water flux and lower reverse salt flux compared with the membrane synthesized without the GO/MWCNT intermediate layer. This method offers promising opportunities to fabricate thin-film composite membranes on microfiltration substrates for FO application with inhibited concentration polarization phenomenon and expected separation performance.

Thin Film Composite Forward Osmosis Membrane with Single-Walled Carbon Nanotubes Interlayer for Alleviating Internal Concentration Polarization

“…From Figure 4a, granular structures with unevenly large leaf-like structures were observed on the TFC 0 membrane surface, which was different from the typical leaf-like structures for the TFC membranes with SWCNTs interlayer. This observation was related to larger pores on the MCE substrate, in which MPD can rapidly diffuse and react with TMC to form large PA oligomers and an initial PA layer [20,42]. The denser surface of MCE/CNTs support layer (Figure 3a) favored the more uniform leaf-like structure of the PA layer, attributing that the SWCNTs interlayer can make the MPD diffusion slow and uniform from aqueous solution to organic solution and thus control the interfacial polymerization reaction [43].…”

“…To reduce the ICP, the support layers with large pore size such as the microfiltration (MF) membrane were used to fabricate TFC membranes, demonstrating that MF substrates could favor a high water flux and a lower S value [19]. However, it is still difficult to form a dense, uniform, and defect-free PA layer on the MF substrates due to a rapid and violent MPD eruption to form large initial PA oligomers and PA layer inside the substrate large pore [20]. Inspired by nanomaterials and nanotechnologies developed, carbon nanotubes (CNTs) with a hollow nano-tubular structure, an excellent chemical stability and polymer-like flexibility [21] were incorporated in the PA layer or support layer to promote the water permeability and selectivity [22,23].…”

“…As reported [24][25][26][27], a CNTs interlayer between the support layer with large pores and the PA layer can fine-tune the surface properties of support layer and control the IP reaction. Zhang et al deposited graphene oxide and multiwall CNTs (GO/MWCNT) composite as an interlayer on polyethersulfone (PES) MF substrate for fabricating TFC membrane with water flux of 26.7 L m −2 h −1 using 1 M NaCl as a draw solution and DI water as a feed solution [20]. Similarly, Zhou et al fabricated TFC FO membrane with an ultrathin interlayer of polydopamine modified single-walled CNTs (PDA/SWCNTs), exhibiting the water flux of~31 L m −2 h −1 and the S value of 197 µm [28].…”

Recent Advances in Applications of Carbon Nanotubes for Desalination: A Review

“…For example, the PA layer in combination with the top surface of the high flux outer-wall CNT membrane exhibits an outstanding performance for desalination due to the ultra-dense porosity and hydrophobicity of the outer-wall CNTs [128]. CNT membranes prepared via a phase inversion method [8] also increases the water flux owing to the existence of CNTs [129][130][131]. In a study, by mixing CNT with graphene oxide (GO), CNTs significantly promoted the water flux via adjusting GO interlayer spacing [130].…”

“…CNT membranes prepared via a phase inversion method [8] also increases the water flux owing to the existence of CNTs [129][130][131]. In a study, by mixing CNT with graphene oxide (GO), CNTs significantly promoted the water flux via adjusting GO interlayer spacing [130]. Furthermore, the CNT hybrid fillers could experience high water permeability using the interfacial polymerization method [97,115,132,133].…”