Photocatalytic water purification under visible light using carbon nitride materials and β-Bi2O3 immobilized on electrospun polyvinyl acetate fibers

Abstract

We report on the immobilization of carbon nitride (CN) materials and β-Bi2O3 on electrospun polyvinyl acetate (PVAc) fiber substrates using a dispersion based dip coating process. The spinning process was optimized by variation of several parameters to finally obtain continuous droplet-free fibers at 15 kV and a flow rate of 50 µL min−1 using a needle with 1.2 mm diameter. The polymer substrates were coated with the β-Bi2O3 and CN materials, which were characterized using SEM and applied in the photocatalytic degradation of organic pollutants such as Rhodamine B (RhB), ethinyl estradiol (EE2) and triclosan using visible light irradiation. The pollutants were degraded with up to 50% of the initial concentration within 8 h. Different amounts of CN material were deposited to evaluate the photocatalytic activity per mass. Immobilized CN materials were shown to be of higher activity (2.0 × 10−10 mol mg−1 min−1) than β-Bi2O3 (1.3 × 10−10 mol mg−1 min−1) and the mixture CN/β-Bi2O3 (1.6 × 10−10 mol mg−1 min−1). Reference samples with CN particles partially embedded in the polymer fleece showed minor degradaton rates (18% RhB degradation within 8 h) as compared to coated fiber substrates (47% RhB degradation within 8 h). Minor leaching of the carbon nitride material and no leaching of β-Bi2O3 occurs as shown by NPOC (non purgeable organic carbon) and ICP-MS measurements.