S- and N-Co-Doped TiO(2)-Coated Al(2)O(3) Hollow Fiber Membrane for Photocatalytic Degradation of Gaseous Ammonia

This study successfully prepared and tested sulfur- and nitrogen-co-doped TiO(2)-coated α-Al(2)O(3) (S,N-doped TiO(2)/Al(2)O(3)) hollow fiber (HF) membranes for efficient photocatalytic degradation of gaseous ammonia (NH(3)). Thiourea was used as a sulfur- and nitrogen-doping source to produce a S,N-doped TiO(2) photocatalyst powder. For comparative purposes, undoped TiO(2) powder was also synthesized. Through the application of a phase-inversion technique combined with high-temperature sintering, hollow fibers composed of α-Al(2)O(3) were developed. Undoped TiO(2) and S,N-doped TiO(2) photocatalyst powders were coated on the α-Al(2)O(3) HF surface to obtain undoped TiO(2)/Al(2)O(3) and S,N-doped TiO(2)/Al(2)O(3) HF membranes, respectively. All prepared samples were characterized using XRD, TEM, XPS, UV-Vis, SEM, BET, FT-IR, and EDS. S and N dopants were confirmed using XPS and UV-Vis spectra. The crystal phase of the undoped TiO(2) and S,N-doped TiO(2) photocatalysts was a pure anatase phase. A portable air purifier photocatalytic filter device was developed and tested for the first time to decrease the amount of indoor NH(3) pollution under the limits of the lachrymatory threshold. The device, which was made up of 36 S,N-doped TiO(2)/Al(2)O(3) HF membranes, took only 15–20 min to reduce the level of NH(3) in a test chamber from 50 ppm to around 5 ppm, confirming the remarkable performance regarding the photocatalytic degradation of gaseous NH(3).