Journal of Health and Safety at Work

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Introduction: Electrospun nanofibers are suitable option to synthesize filtering mats for nanoparticles. This study was aimed to fabricate polyurethane nanofiber mats through electrospinning process and to investigate the effect of different parameters such as packing density, face velocity and particle type on the filtration efficiency and quality factor of electrospun polyurethane nanofiber mats.
 

Material and Method: The nanofiber mats were produced by electrospinning  process. Polyurethane granules were dissolved (15w/w%) in a solvent system consisting of dimethylformamide and tetrahydrofuran (3:2). Then, the filtration performance testing system was made at the Fluid Mechanics Department of Hanyang University of South Korea and the filtration efficiency and pressure drop of prepared nanofiber mats were studied.
 

Result: Findings showed that by increasing the duration of electrospinning, the basis weight, thickness, packing density, initial pressure drop and filtration efficiency of the mats increased, and the quality factor of the mats decreased due to the increase of the pressure drop. The increase in electrospinning duration from 15 to 45 minutes was led to the increase in pressure drop from 7 to 32 Pa and the average filtration efficiency was increased about 9-10% for KCl and DEHS test particles. The filtration efficiency and quality factor of the prepared polyurethane nanofiber mats were declined with the increase of filtration face velocity from 2 to 5 and 10 cm/s. The reduction in filtration efficiency was more obvious for particles smaller than 425 nm.
 

Conclusion: The results demonstrated that prepared polyurethan naofiber mats provide acceptable filtration performance. What is more, such nanofiber mats can have other potential benefits such as light basis weight, low thickness and simple production.

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Introduction: Despite nanofibers have attracted great interests for filtering particulate matters from the air stream, fewer studies have been done on the feasibility of their use in the removal of gas pollutants, while the both pollutants are present in the most workplaces. Toluene is a toxic and mutagenic substance, and chronic exposure to its low levels can lead to a wide range of adverse health effects on people who exposed. The purpose of this study was to produce polymer /single-walled carbon nanotube hybrid nanofibers by electrospinning technique and doing plasma surface treatment and evaluating their removal efficiency of toluene from air stream.  
Material and Methods: The nanofiber layers were fabricated by electrospinning solution containing polyacrylonitrile polymer (PAN) and single-walled carbon nanotube (SWNT) with a 99: 1 ratio under following conditions: applied voltage 20 kV, distance between needle and collector: 10 cm, injection rate: 1 ml / h; needle diameter: 18 gauge and drum speed ranging from 1000 to 500 rpm. The surface of the manufactured nanofibers was treated by cold-plasma with a radio frequency power supply (13.56 MHz with a power of 20 watts), argon gas and operating pressure of 0.2 torr. Test conditions was prepared according to standard ISO 10121-1: 2014, which provides a method for testing the performance of gas-phase air filter for a variety of flat sheet media. In order to measure the concentration of toluene, the First check – handheld multi gas VOC detector equipped with a PID detector was used. The morphology characteristics of the fibers was performed using the analysis of scanning electron microscope images. Infrared spectroscopy-Fourier transform was used to identify organic compounds and functional groups in nanofibers.
Results: The results of the analysis of the images showed that the mean diameter of the fiber was 169.16 ± 7.19 nm and the mean coefficient of variation was 0.23. The uniform and bead nanofibers were obtained. The thickness, porosity and air permeability coefficient of test media was 0.15 mm, 43% and 5.75 Darcy, respectively. The mean removal efficiency of PAN / SWNT nanofiber treated with plasma was 98% and the mean pressure drop was 100 Pascal. The FTIR spectrum of the test filter media showed that the peaks appearing at certain wavelengths related to the vibration of C-H aliphatic groups of C-C and C=O bands related to PAN polymer and carbon nanotubes.
Conclusion: Removal of toluene was achieved through the fabrication of PAN/SWNT hybrid nanofibers treated with plasma. Uniform nanofibers were obtained and showed the proper removal efficiency and low pressure drop.