Novel nanofibrous scaffolds for water filtration with bacteria and virus removal capability

Abstract

We demonstrate a new class of composite fibrous membranes, consisting of an ultra-fine cellulose nanofibrous network infused into an electrospun polyacrylonitrile (PAN) nanofibrous scaffold on a melt-blown polyethylene terephthalate (PET) non-woven substrate for water purification. Depending on the infusion process and the ultra-fine cellulose nanofibers (UFCNs) used [e.g. modified ultra-fine cellulose nanofibers (m-UFCNs) or microcrystalline cellulose nanofibers (MCCNs)], different nanostructured scaffolds were formed as seen by electron microscopy. Membranes with UFCNs consist of an interwoven two-dimensional ultra-fine nanofibrous network that is deeply entangled with the electrospun scaffold and organized in a quasi-three-dimensional fashion, while those with MCCNs tend to locally wrap around the electrospun scaffolding nanofibers without forming a major network. Filtration tests illustrated that both membranes, while maintaining high permeation flux, exhibited excellent retention capabilities for simultaneous sieving for bacteria and adsorption for viruses.

A review on electrospun bio-based polymers for water treatment

“…The mechanical properties of the resulting electrospun nanofibrous membrane (ENM) were improved by the presence of the whiskers, with the tensile strength increasing from 4 to 10 MPa (for one coating of the whiskers onto the ENM) and 14 MPa (for double coating). Cellulose nanowhiskers and nanofibres have also been thoroughly studied by the Chu and Hsiao group in water treatment and filtration applications [149][150][151][152]. The cellulose nanowhiskers were either employed as barrier layer of thin-film nanofibrous composite membranes (TFNC) (Figure 8), or they were infused into the electrospun membrane, depending on the intended filtration application (microfiltration (MF) or UF).…”

“…Among the cellulose derivatives, cellulose acetate (CA) is the most studied derivative due to its potential to regenerate pure cellulose via deacetylation [23,152]. Cellulose acetate is synthesized by acetylation of the hydroxyl groups on cellulose with an average of 2-4 degree of substitution per glucose units ( Figure 10).…”

“…TNFC membranes have been one of the growing subjects in water filtration, because of the performance displayed by these materials since the introduction of electrospun nanofibres as one of the sub-layers. Several researchers found that the coating of these TNFC with cellulose nanowhiskers imparts significant hydrophilicity and mechanical properties to the membrane [144,[149][150][151][152]. The thin top-layer coating enhanced the rejection and flux.…”

Electrospun Nanofiber Membranes and Their Applications in Water and Wastewater Treatment

“…Conventional synthetic polymers such as polyvinylidene fluoride (PVDF) were first used as battery separator as well as in fuel cell and solar cell applications [22,23] and later in ultrafiltration and membrane distillation applications [18,24]. Other polymers such as polyacrylonitrile (PAN) [25][26][27][28][29][30], CA [31][32][33], and PEO [14,34] were electrospun alone or together with other copolymers. Natural polymers such as silk [35][36][37] and chitin [38] have also been electrospun.…”

“…Recently, Sato et al [30] developed a novel nanofiber membrane capable of removing both bacteria and viruses while maintaining the flux. This composite membrane consists of cellulose ultra-fine fibers infused into a PAN ENM on a nonwoven substrate.…”