RESUMEN
In this work, a nylon 6 nanofibrous membrane was prepared via solution blowing technology and followed hot-press as scaffold for nanofiltration. The structure and properties of the hot-pressed nylon 6 nanofibrous membrane (HNM) were studied the effect of hot-pressing parameters and areal densities. Then an ultra-thin polyamide (PA) active layer was prepared by interfacial polymerization on HNM. The effects of nanofibrous scaffolds on the surface properties of ultra-thin nanofiltration membranes and their filtration performance were studied. Results showed that the nylon 6 nanofibers prepared at a concentration of 15 wt % had a good morphology and diameter distribution and the nanofibers were stacked more tightly and significantly reduced in diameter after hot pressing at 180 °C under the pressure of 15 MPa for 10 s. When the porous scaffold was prepared, HNM with an areal density of 9.4 and 14.1 g/m² has a better apparent structure, a smaller pore size, a higher porosity and a greater strength. At the same time, different areal densities of HNM have an important influence on the preparation and properties of nanofiltration membranes. With the increase of areal density, the uniformity of HNM increased while their surface roughness and pore size decreased, which is beneficial to the establishment of PA barrier layer. With areal density of 9.4 and 14.1 g/m², the as-prepared nanofiltration membrane has a smoother surface and more outstanding filtration performance. The pure water flux is 13.1 L m-2 h-1 and the filtration efficiencies for NaCl and Na2SO4 are 81.3% and 85.1%, respectively.
RESUMEN
Detoxification reaction of chloropicrin in the human body with biological thiols was selected for detection of chloropicrin in the air. The consumption of free sulfhydryl group in biological thiols by chloropicrin is colorimetrically detectable with the addition of the Ellman's reagent. In this study, glutathione, N-acetyl-l-cysteine, l-homocysteine, cysteamine, and thioglycolic acid were tested as sensing agents for chloropicrin vapor detection in ppb concentration range. The reactivity of the selected biological thiols was investigated based on both their redox properties and the nucleophilic strength of the sulfhydryl groups. Nylon-6 nanofibrous membrane and an organic solvent were used as a sensor matrix and a vapor sorbent, respectively, to provide solid supports with ultrahigh surface area and enhanced adsorption to chloropicrin vapor. The tunable sensitivity and detection range by using different biological thiols was achieved on the sensors due to the different reactivity of thiols toward chloropicrin.