Processing Nomex Nanofibers by Ionic Solution Blow‑Spinning for Efficient High‑Temperature Exhausts Treatment

Hard-to-dissolve polymers provide next-generation alternatives for high-performance filter materials owing to their intrin-sically high chemical stability,superior mechanical performance,and excellent high-temperature resistance.However,the mass production of hard-to-dissolve nanofibers still remains a critical challenge.A simple,scalable,and low-cost ionic solu-tion blow-spinning method has herein been provided for the large-scale preparation of hard-to-dissolve Nomex polymeric nanofibers with an average diameter of nearly 100 nm.After rapidly dissolving Nomex microfibers in the lithium chloride/dimethylacetamide(LiCl/DMAc)solution system,the conductive solution can be stably and conductivity-independently processed into nanofibers.The method optimizes electrospinning and avoids spinnability degradation and potential safety hazards caused by high electrical conductivity.Owing to nanofibrous structure and high dipole moment,Nomex nanofibrous filters show a stable high filtration efficiency of 99.92%for PM_(0.3) with a low areal density of 4.6 g m^(-2),as well as a low-pressure drop of 189.47 Pa.Moreover,the flame-retardant filter can work at 250°C and 280°C for a long and short time without shrinking or burning,respectively,exhibiting a high filtration efficiency of 99.50%for PM_(0.3-10.0).The outstanding properties and low cost enable the efficient capture of PM from various high-temperature exhausts,making Nomex nanofi-brous membrane an even more ideal industrial-grade air filter than polypropylene,polytetrafluoroethylene,polyimide,and ceramic nanofibrous filters.

Bifunctional Activated Carbon Ultrathin Fibers:Combining the Removal of VOCs and PM in One Material

Volatile organic compounds(VOCs)and particulate matter(PM)are both frequently present in air as contaminants,posing serious health and environmental hazards.The current filtration of VOCs utilizes entirely different materials compared with PM filtration,adding complexity to air cleaning system.Herein,we design a pitch-based activated carbon ultrathin fibers(PACUFs)for bifunctional air purification.The PACUFs,with fiber diameter of∼1.2μm and specific surface area of 2341 m^(2) g^(−1),provide both high VOCs adsorption capacity(∼706 mg g^(−1))and excellent efficiency of∼97% PM_(0.3) filtration with low pressure drop.In contrast,traditional activated carbon fibers exhibit VOCs adsorption capacity of∼448 mg g^(−1) and PM_(0.3) removal efficiency of only∼36%at an equal area density of∼190 g m^(−2).Theoretical investigations reveal the filtration mechanism of the high-performance bifunctional fibrous PACUFs,considering full advantages of the high surface area,small pore size,and significant micropore volume.