ABSTRACT
In view of the practical application, it is imperative to develop efficient, exercisable, and visible light driven water pollution treatment materials. Herein, a high-efficiency green photocatalytic membrane for water pollution treatment is proposed and fabricated conveniently. Firstly, silver phosphate (Ag3PO4) nanoparticles with controlled morphology were prepared by simple liquid-phase precipitation method, and then a hierarchical structured Ag3PO4@polylactic acid (PLA) composite nanofiber membrane was prepared by electrospinning. Using electrospun PLA nanofiber membrane as a carrier of photocatalysts can significantly improve the dispersion of Ag3PO4nanoparticles, and increase the contact probability with pollutants and photocatalytic activity. The prepared PLA@Ag3PO4composite membrane was used to degrade methylene blue (MB) and tetracycline hydrochloride (TC) under visible light irradiation. The results showed that the removal ratio of pollutants on Ag3PO4@PLA composite nanofiber membrane was 94.0% for MB and 82.0% for TC, demonstrating an outstanding photocatalytic activity of composite membrane. Moreover, the PLA nanofiber membrane is a self-supported and biodegradable matrix. After five cycles, it can still achieve 88.0% of the initial photocatalytic degradation rate towards MB, showing excellent recyclability. Thus, this composite nanofiber membrane is a high-efficiency and environmental-friendly visible light driven water pollution treatment material that could be used in real applications.
ABSTRACT
As researchers are striving to develop high-performance filtration membranes with hierarchical micro/nano structures, the challenges and costs of processing often limit creative innovation. Here, we propose a polyethersulfone/polyacrylonitrile (PES/PAN) nanofiber membrane with groove structure by electrospinning and facile post-processing. The resulted membrane can form a groove structure on the surface of the fiber after being soaked in chloroform, thereby increasing the collision probability and extending the residence time for ultrafine particulates and improving the filtration efficiency. The groove structure can be attributed to the solubility of PES constituent in chloroform, while PAN constituent will not be dissolved, thus forming a high-performance nanofiber membrane with high filtration efficiency (ca. 99.54%) and withstand pressure drop (ca. 133.9 Pa) for dioctyl phthalate aerosol particles with diameter of 0.3µm. The results show that this convenient and low-cost fabrication technology can be used to prepare high-performance nanofiber membrane based air filters that have broad application prospects in respiratory protective equipment.
ABSTRACT
Pressure sensors have been widely used in electronic wearable devices and medical devices to detect tiny physical movements and mechanical deformation. However, it remains a challenge to fabricate desirable, comfortable wearing, and highly sensitive as well as fast responsive sensors to capture human body physiological signs. Here, a new capacitive flexible pressure sensor that is likely to solve this problem was constructed using thermoplastic polyurethane elastomer rubber (TPU) electrospinning nanofiber membranes as a stretchable substrate with the incorporation of silver nanowires (AgNWs) to build a composite dielectric layer. In addition, carbon nanotubes (CNTs) were painted on the TPU membranes as flexible electrodes by screen printing to maintain the flexibility and breathability of the sensors. The flexible pressure sensor could detect tiny body signs; fairly small physical presses and mechanical deformation based on the variation in capacitance due to the synergistic effects of microstructure and easily altered composite permittivity of AgNW/TPU composite dielectric layers. The resultant sensors exhibited high sensitivity (7.24 kPa-1 within the range of 9.0 × 10-3 ~ 0.98 kPa), low detection limit (9.24 Pa), and remarkable breathability as well as fast responsiveness (<55 ms). Moreover, both continuously pressing/releasing cycle over 1000 s and bending over 1000 times did not impair the sensitivity, stability, and durability of this flexible pressure sensor. This proposed strategy combining the elastomer nanofiber membrane and AgNW dopant demonstrates a cost-effective and scalable fabrication of capacitive pressure sensors as a promising application in electronic skins and wearable devices.
