Fabrication of Nanofiltration Membrane based on Polyvinyl Alcohol Nanofibers Reinforced with Cellulose Nanocrystal using Electrospinning Techniques

Filtration is an effective method in any process concerning the removal of potential infective substances via a size separation mechanism. The filter can be made from various materials. This research analyzes the fabrication of nanofiltration membranes made from polyvinyl alcohol (PVA) nanofibers reinforced with ramie cellulose nanocrystal (CNC) using the electrospinning method. The physical and mechanical properties of the filters were investigated with varying CNC concentrations in PVA to investigate the effect of the CNC content. The results showed that the fiber diameter in the membranes was not significantly related to the CNC content. However, the strength and elongation increased with an increase in CNC concentration until a certain value was reached, at which point it started decreasing. The SEM image showed that the membrane nanofibers have a pore size small enough to be used in a nanofiltration process. SEM-EDX and TGA/DSC testing were also carried out to determine the elements in the membrane and show the suitability of the thermal resistance.

Cellulose nanocrystal; Electrospinning; Nanofiber membrane; Polyvinyl alcohol

The Covid-19 virus is currently a global pandemic, with the first outbreak identified in Wuhan, China, in 2019. Since then, the virus has spread around the world. Therefore, it is essential to take the right steps to break the chain of its transmission. One of the strategies for preventing its transmission includes creating a nanofiber filter with smaller pores than the virus. This is because nanofibers show prospective filtration due to their controlled fiber diameter, high specific strength, high surface area, and mat pore size (Sanders et al., 2019).

     The nanofiber is a fiber nano-sized in diameter. It can be produced from various types of polymers, including polyvinyl alcohol (PVA). Reinforcements for these polymers are valuable for strengthening their properties. The use of cellulose nanocrystal (CNC) as a reinforcement in the nanofiber membrane is supportive due to its nano dimensions, high aspect ratio, high crystallinity, low density, high mechanical strength, unique morphology, addition to these benefits, CNCs also have better properties than other fibers, including glass, steel wire, Kevlar, and graphite (Kim et al., 2015).

This study utilized cellulose from ramie fiber, which is a natural fiber containing 76% cellulose, 17% hemicellulose, and 1% lignin (Heinze et al., 2018). However, studies on the use of ramie fibers as CNCs are scarcely found. The utilization is limited to handicrafts and fabrics despite its abundance in Indonesia due to its ability to grow adequately in any tropical region with good productivity. Cellulose can also be extracted from many other natural materials besides ramie fiber. For example, Helmiyati and Anggraini (2019) successfully researched the production of cellulose from rice husks.

Polyvinyl alcohol is a low-cost, water-soluble, biocompatible polymer used in many biomedical applications (Sousa et al., 2015). For these reasons, the combination of ramie CNC and PVA is expected to produce an excellent composite material with a higher strength in the nanofiber membrane.

In this study, a ramie CNC-filled PVA nanofiber membrane was manufactured using an electrospinning method. This technique is widely used for the production of membrane nanofibers despite the potential use of other methods, such as sol-gel (Poerwadi et al., 2020), screening and drying a composite solution to form a rougher result (Rochardjo et al., 2019), or spin coating followed by direct immersion in distilled water of polyethersulfone (Prihandana et al., 2015). With electrospinning, PVA fibers can be produced with a diameter ranging from ten to hundreds of nanometers (Rezaei et al., 2016).

    The fabrication of composite nanofiber membranes from CNC ramie fiber and PVA has been successfully conducted. Due to the average pore size of 11.8 nm in nanofiber membranes, it can be used as a nano-filtration process in general. The addition of 5% CNC ramie fiber (v/v) has a positive impact on the tensile strength and elongation of the nanofiber membrane. The membrane was produced perfectly with a voltage of 15 kV and a distance between the tip and collector of 12 cm.  However, at higher CNC contents, it needs further investigation, since the resulting membrane was not good, as shown by the existence of defects on the membrane that resulted in lower mechanical properties. The thermal resistance of the nanofiber membrane is in the temperature range of 300^oC–340^oC; therefore, the membrane is safe when used at room temperature and higher.

    The authors would like to acknowledge the Department of Mechanical and Industrial Engineering Universitas Gadjah Mada for providing research equipment and supporting the publication.

ASTM D638–14 type V:2020. Standard Test Method for Tensile Properties of Plastics; ASTM International: West Conshohocken, PA, USA, 2020

Darmanto, S., Rochardjo, H.S.B., Jamasri, Widyorini, R., 2017. Effects of Alkali and Steaming on Mechanical Properties of Snake Fruit (Salacca) Fiber In: AIP Conference Proceedings, 1788 (January)

Fatkhurrohman, 2019. Fabrication And Characterization Of Nanocomposite Membrane From Nanocellulose Ramie Fiber With PVA Matrix, Master Thesis, Graduate School of Mechanical Engineering, Universitas Gadjah Mada, Yogyakarta

Heinze, T., El Seoud, O.A., Koschella, A., 2018. Production and Characteristics of Cellulose from Different Sources. Cellulose Derivatives, Springer Series on Polymer and Composite Materials. Springer, Cham., pp. 1–38

Helmiyati., Anggraini, Y., 2019. Nanocomposites Comprising Cellulose and Nanomagnetite as Heterogeneous Catalysts for the Synthesis of Biodiesel from Oleic Acid. International Journal of Technology, Volume 10(4), pp. 798–807

Hulupi, M., Haryadi, H., 2019. Synthesis and Characterization of Electrospinning PVA Nanofiber-Crosslinked by Glutaraldehyde. Materials Today: Proceedings, Volume 13(1), pp. 199–204

Jeong, J.S., Moon, J.S., Jeon, S.Y., Park, J.H., Alegaonkar, P.S., Yoo, J.B., 2007. Mechanical Properties of Electrospun PVA/MWNTs Composite Nanofibers. Thin Solid Films, Volume 515(12), pp. 5136–5141

Kim, J.H., Shim, B., Kim, H.S., Lee, Y.J., Min, S.K., Jang, D., Abas, Z., Kim, J., 2015. Review of Nanocellulose for Sustainable Future Materials. International Journal of Precision Engineering and Manufacturing – Green Technology, Volume 2(2), pp. 197–213

Poerwadi, B., Kartikowati, C.W., Oktavian, R., Novaresa, O., 2020. Manufacture of a Hydrophobic Silica Nanoparticle Composite Membrane for Oil-Water Emulsion Separation. International Journal of Technology, Volume 11(2), pp. 364–373

Prihandana, G.S., Sriani, T., Mahardika, M., 2015. Review of Surface Modification of Nanoporous Polyethersulfone Membrane as a Dialysis Membrane. International Journal of Technology, Volume 6(6), pp. 1025–1030

Rezaei, A., Tavanai, H., Nasirpour, A., 2016. Fabrication of Electrospun Almond Gum/PVA Nanofibers as a Thermostable Delivery System for Vanillin. International Journal of Biological Macromolecules, Volume 91, pp. 536–543

Rochardjo, H.S.B., Jamasri, J., Yudhanto, F., 2019. Extraction of Natural Fibers by High-Speed Blender to Produce Cellulose Sheet Composite. International Review of Mechanical Engineering, Volume 13(12), pp. 691–699

Sanders, J.E., Han, Y., Rushing, T.S., Gardner, D.J., 2019. Electrospinning of Cellulose Nanocrystal-Filled Poly (Vinyl alcohol) Solutions: Material Property Assessment. Nanomaterials, Volume 9(5), pp. 1–16

Segal, L., Creely, J.J., Martin, A.E., Conrad, C.M., 1959. An Empirical Method for Estimating the Degree of Crystallinity of Native Cellulose Using the X-Ray Diffractometer. Textile Research Journal, Volume 29(10), pp. 786–794

Silvério, H.A., Flauzino Neto, W.P., Dantas, N.O., Pasquini, D., 2013. Extraction and Characterization of Cellulose Nanocrystals from Corncob for Application as Reinforcing Agent in Nanocomposites. Industrial Crops and Products, Volume 44, pp. 427–436

Sousa, A.M.M., Souza, H.K.S., Uknalis, J., Liu, S.C., Gonçalves, M.P., Liu, L., 2015. Electrospinning of Agar/PVA Aqueous Solutions and its Relation with Rheological Properties. Carbohydrate Polymers, Volume 115, pp. 348–355

Yudha, V., Rochardjo, H.S.B., Jamasri, J., Widyorini, R., Yudhanto, F., Darmanto, S., 2018. Isolation of Cellulose from Salacca Midrib Fibers by Chemical Treatments. IOP Conference Series: Materials Science and Engineering, Volume 434(1), p. 1–5

Yudhanto, F., Jamasri, Rochardjo, H.S.B., 2018. Physical and Thermal Properties of Cellulose Nanofibers (CNF) Extracted from Agave Cantala Fibers Using Chemical-Ultrasonic Treatment. International Review of Mechanical Engineering, Volume 12(7), pp. 597–603