Textiles with fire detection will appeal for the interior
decoration
of houses and play a critical role in public security. Herein, we
fabricated a sandwichlike fire alarm fabric (Ag@Fe3O4-MS) based on Fe3O4 nanowire (NW) arrays
and fish-scale-like silver sheets, designed by in situ layer-by-layer
assembly on the surface of polypropylene (PP) nonwoven fabric. The
Ag@Fe3O4-MS sensor has fish-scale-like silver
sheets as self-assembling electrode layers on the upper and lower
sides of fabric, which can be tailored into various shapes and integrated
into other flexible electronics. The sensor provides a real-time monitoring
strategy for early warning fire detection (below 100 °C). At
room temperature, the fabricated Ag@Fe3O4-MS
sensor is electrically insulating, while it switches to an electrical
conductor when exposed to flame. In view of its fast response time
(2 s) and sustained working time (at least 15 min), the sensor with
a connected alarm light can immediately alert people of house fires.
More importantly, this sensor can provide additional real-time information
on the fire location and reliable real-time monitoring of fire rekindling.
The sensor was exposed to fire for successive cycles with an average
response of I = 43 mA, confirming the reliable
repeatability to detect fires. This ultralight, flexible Ag@Fe3O4-MS sensor could have broad applications in home
safety. Moreover, the sandwichlike design provides a reliable strategy
to modify household fabric items to provide a fire warning function.
This work provides a cost-effective approach for preparing functional polymeric fibers used for removing uranium (U(VI)) from carbonate solution containing NaF. Phosphate-based ultrahigh molecular weight polyethylene (UHMWPE-g-PO4) fibers were developed by grafting of glycidyl methacrylate, and ring-opening reaction using phosphoric acid. Uranium (U(VI)) adsorption capacity of UHMWPE-g-PO4 fibers was dependent on the density of phosphate groups (DPO, mmol∙g−1). UHMWPE-g-PO4 fibers with a DPO of 2.01 mmol∙g−1 removed 99.5% of U(VI) from a Na2CO3 solution without the presence of NaF. In addition, when NaF concentration was 3 g∙L−1, 150 times larger than that of U(VI), the U(VI) removal ratio was still able to reach 92%. The adsorption process was proved to follow pseudo-second-order kinetics and Langmuir isotherm model. The experimental maximum U(VI) adsorption capacity (Qmax) of UHMWPE-g-PO4 fibers reached 110.7 mg∙g−1, which is close to the calculated Qmax (117.1 mg∙g−1) by Langmuir equation. Compared to F−, Cl−, NO3−, and SO42− did not influence U(VI) removal ratio, but, H2PO4− and CO32− significantly reduced U(VI) removal ratio in the order of F− > H2PO4− > CO32−. Cyclic U(VI) sorption-desorption tests suggested that UHMWPE-g-PO4 fibers were reusable. These results support that UHMWPE-g-PO4 fibers can efficiently remove U(VI) from carbonate solutions containing NaF.
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