The present project depicts the formation and characterization of electrospun nanofibrous mat generated from the recycled PET bottle using electrospinning technique as well as introduce nanofiber facemask from this nano mat having features to inhibit viruses and bacteria.
The morphological structure, bonding behavior, and moisture management of the developed nano-mats were investigated by SEM, FTIR, MMT respectively.
The SEM analysis showed the homogenous and smooth fiber and FTIR ensure the presence of polyethylene terephthalate. Owing to high filtration performance, low toxicity, breathability, reusability, ecofriendly, and commercially viable this face mask is a time demanded product for Bangladesh.
Thus, the developed mats have great potential for use as a face mask in this COVID-19 pandemic situation. Besides, it will also decrease the environmental pollution caused by PET bottles. Furthermore, it will open a new window for protective textiles.
Keywords: electrospinning, PET, facemask, nanotechnology, protective textiles.
The formation of nanofiber by electrospinning technique using natural, modified natural and synthetic polymers has gained a great deal of interest over the decades for their applications in biomedical fields, such as wound dressing, tissue engineering, filtration media, and drug delivery due to their biocompatibility, biodegradation, low toxicity, high porosity, lightweight and, most importantly, wide surface area.
The simple electrospinning configuration consists of four components: a syringe filled with a polymeric solvent, a metal needle, a kV power supply, and a metal collector.
Besides, Polyethylene terephthalate (PET) is one of the most commonly used synthetic polymers in the world and is the most preferred packaging material for drinks. However, according to Forbes Magazine, < 10 percent of PET bottle plastics are recycled in 2017. This means that over 90% of PET bottles have been disposed of or burned, posing significant environmental threats as they have existed in existence for many years and are made from dwindling oil resources.
Filtration plays a significant role in purifying and decontaminating the two essentials of life: water and air[12-14]. As the consciousness of associated health problems has risen, the need for more protection from airborne contamination and disease has also increased[8,15,16] ]. From this viewpoint, scholars’ going to clarify the special and enhanced capacity that electrospun nanofibres have when used as an active layer in face masks. Compared to common melt-blown filters, electrospun nanofibres have stronger protection against air pollutants, bacteria, and viruses such as COVID-19.[17-21]
Thus, the objective of this project is to manufacture antibacterial, anti-droplet, non-toxic, environmentally sustainable face masks using recycled PET.
Materials and methods
The PET bottles were collected and converted into polymer chips in the local area of Gazipur city, Dhaka, Bangladesh. Trifluoroacetic acid (TFA) was sourced from Loba Chemical (India) and dichloromethane (DCM) from Merck, Germany. All the chemicals were of analytical grade and used without further purification.
Preparation of recycled PET solution
The prepared recycled PET bottle chips PET solutions were prepared in concentrations of 20wt.% (w/v) in the mixture of solvents DCM/TFA in the specific ratio. To proper dissolving, the PET polymer solution keep 24 hours at ambient condition. After that, the prepared solution is then transferred via a syringe (20 mL) to the pump.
Electrospinning process of recycled PET nanofibrous mats
Nanofibers from the recycled PET polymer have been studied in the present study were produced by solution electrospinning technique (needle-based system). Initially, the collected PET bottle was washed perfectly with fresh water and dried in an oven at 400˚C.
Then the dried PET bottle was finely converted to chip form by a local machine and 20 gm PET chips were taken in a flask containing 80 ml TFA and 20 ml DCM.
The flask was kept aside for 24 hours at ambient to ensure perfect maceration. In this study, electrospinning set-up consisted of a high voltage supply (20kV and 50 KV), a syringe pump (TL-F6, Tong Li Tech, China), a rotary drum collector (diameter-158mm, length-500mm, 500 rpm), a heater (0.5 kW) and 5 needles (20 Gauge). All the components were used as a single.
Measurement of moisture management
The moisture management property of the developed mat was evaluated by a moisture management tester (MMT) (M290, SDL Atlas, UK) according to AATCC 195-2009. Wetting time, absorption rate, maximum wetted radius, and spreading speed of inner and outer surface including accumulative one-way transport capacity (R) and overall moisture management capacity (OMMC) were measured.
The morphological orientation of nanofibers was noticed by SEM (SU 1510, Hitachi, Japan) at a magnification of 3000 and 500 with a voltage of 15KV to get images with appropriate quality. Besides, the porosity of the dry nanofibrous mat was determined by weighting the samples and calculating their volume from the thickness and area measurements. The porosity of the fibrous mat was estimated from Equation (1).
Where q is the apparent density of the electrospun mat and q0 is the density of the bulk polymer.
Fourier transforms infrared spectroscopy (FTIR)
The chemical characteristics of recycled PET nano mat and nano mat mask were characterized using an FTIR (IRPrestige21, Shimadzu Corporation, Japan). The spectra of all the different ratio samples were recorded in the 400–4000 cm-1 range with 4 cm-1 resolution. All result appears in a satisfactory level.
Results and discussion
In this project, we have produced a PET bottle-based nano-fibrous mat to apply in a facemask. In this section, the answer to some common questions has attached.
Internationally, the need for nanofibre continues to expand, which is why we have scaled up to increase supply to meet the demand not just for filter media but also for our full range of goods.
For use infiltration, NF fabrics developed by electrospinning have attracted interest. This is partly because the nanofibre diameter is 10-100 times smaller than that of regular MB microfibers. In nanofibres, the higher surface area induces better filtration efficiency, primarily because the primary driving force in air filtration is surface interaction.
Measurement of moisture management
The MMT test of the only nanofiber shows wetting time 19.84 s and 13.19 top and bottom surface respectively. Other results are satisfactory level for using this nano mat in the facemask.
On the other hand, when attaching it with another mask layer then obtained 9.64 and 120 respectively for both surfaces. Since the mask layer is very thin thus water can’t reach the bottom surface. Other results are satisfactory.
The morphological structure of the recycled nano-matt shows tiny porous which has the prospect to prevent viruses and bacteria.
Why are there better electrospun masks?
Many harmful particulate pollutants have a diameter smaller than 1 micrometer. Conventional mechanical fibrous filters (such as melt-blown filters) eliminate high-quality micrometer-sized particles. Electrospun nano filter, however, is considered best for particles in the submicron range as they give the enhanced quality of filtration. This is due to their high area of the surface and the small diameter of the pore.
Breathing comfort is generally correlated with a pressure drop. Another significant aspect to remember is the transportation of moisture, In a recent study, It has been observed that the ES NF filters’ WVTR was superior.
In our test report, ES NF filters have a finer structure and morphology and a more uniform pore diameter. This makes it possible to more consistently and effectively transfer the water vapor through the filter.
Research has been conducted on the reusability of MB and when washed with ethanol (sprayed and dipped), electrospun nanofiber filters. The results showed ES NF filters can be successfully reused many times as the filtration efficiency remains constant (about 96.5 percent).
Is it commercially viable?
Historically, nanofibers could not be manufactured in large enough quantities and at low enough cost to be economically feasible against existing alternatives such as meltblown. Recent technical developments have ensured that the output rate of electrospun nanofibre is similar to that of the traditional melt blowing process.
The chemical characteristics of recycled PET nano mat and nano mat mask were characterized using an FTIR (IRPrestige21, Shimadzu Corporation, Japan). The spectra of all the different ratio samples were recorded in the 400–4000 cm-1 range with 4 cm-1 resolution. All result appears at a satisfactory level.
To appreciate how ES NFs (Electrospun Nanofiber) boost filtration efficiency, understanding the process of particle capture is important. Five different mechanisms can obstruct particles through a filter: Sieving, Interception, Diffusion, Inertia Impaction, and Electrostatic Attraction (Figure-10).
Gravity can aid the process of filtration, but for particles smaller than 600 nm, it is mostly considered negligible. As seen in Figure 1, particles can be divided into various sizes.
Flow chart of Electrospinning
Raw material cost is negligible and excluding machinery cost:
Lab-scale production cost- Approximately 10-12 Tk per mask
Bulk scale- Approximately 5-6 Tk per mask.
In this project, an electrospun nanofibrous mat has been successfully produced from recycled PET bottles by electrospinning technique. The morphology, strength, and other physical properties of this nano mat is brilliant.
Because of its improved biocompatibility, biodegradability, low toxicity, and intrinsically large surface area; nanofibrous mat produced from natural and synthetic polymer have sought great attention. Infrared spectroscopy confirmed the presence of a functional PET functional group in the nano mat.
Most of the pollutant partials have at the micro-level and some are nano level. Where virus and bacteria can penetrate through the conventional non-woven mask but can’t through nanofibrous face mask due to nano scle porus.
Because of unique technology and understanding of customer satisfaction, high protection so this mask will have a prospect of monopoly business. Covering the national demand, Bangladesh can emerge as a medical textile supplier in the global market. This is where the project stands.
Department of Textile Engineering, DUET, Gazipur and Bangladesh Jute Research Institute (BJRI) are thankfully acknowledged.
There is no conflict of interest.