Fabrication of zeolite NaX-doped electrospun porous fiber membrane for simultaneous ammonium recovery and organic carbon enrichment

Preparation of a hydrophilic nanofiber membrane by electrospinning for application in the detection of NO2 by chemiluminescence

The strong hydrophobicity of the PVDF membrane is prone to contamination that is hard to clean for long-term usage. In this study, hydrophilic and antifouling nanofiber membranes (NMs) were prepared with the hydrophilic polymer PVP and inorganic nanoparticles TiO2NPS. This NM was found to have excellent cleanability and good recyclability. Within 30 minutes, the residual ions could be removed by cleaning with deionized water. In alkaline solutions with the power of hydrogen (PH) ≤10, NM exhibits good alkaline resistance and recycling performance. It was also found, for the first time, that TiO2NPS could enhance the sensitivity of Luminol-NO2 (L-NO2) by 4 times. The detection of NO2 concentration by NM presents an excellent linear relationship with the chemiluminescence reading. This linear relationship would aid quick and convenient detection of NO2 using chemiluminescence.

Colloidal Stabilization of Submicron-Sized Zeolite NaA in Ethanol-Water Mixtures for Nanostructuring into Thin Films and Nanofibers

Despite the growing use of organic or mixed solvents in zeolite processing, most studies focus only on aqueous suspension systems. We investigated the colloidal characteristics of submicron-sized zeolite NaA in mixed ethanol-water solvents. The effects of the mixing ratio of solvents and various additives on the dispersion of the zeolite powders were studied. The zeolite NaA particles were destabilized in solvent mixtures at a high ethanol-to-water ratio, a reduction in the zeta potential was observed, and the destabilization was rationalized by the Derjaguin, Landau, Verwey, Overbeek (DLVO) theory. An improved stabilization of the zeolite NaA suspensions was achieved in ethanol-rich solvent mixtures using nonionic low molecular weight organic additives, but not with their ionic counterparts such as anionic, cationic surfactants or inorganic acids or bases. Polyethylene glycol (PEG)-400 was found to be a good dispersant for the submicron-sized zeolite NaA particles in the ethanol-water mixtures, which was attributed to its interaction with the zeolite surface, leading to an increased zeta potential. The PEG-stabilized zeolite suspensions led to low suspension viscosities as well as uniform and consistent spin-coated films.