Microstructure and photocatalytic properties of Ag/Ce⁴⁺/La³⁺ co-modified TiO₂/Basalt fiber for ammonia–nitrogen removal from synthetic wastewater

Ag/Ce⁴⁺/La³⁺ (1, 3, and 5 wt.%) co-modified titanium dioxide powder and modified Titanium dioxide coated basalt fiber photocatalysts were prepared via sol–gel method. The properties of the photocatalysts were characterized in detail by using transmission electron microscopy, field-emission scanning electron microscopy, UV–visible absorption spectra, X-ray powder diffraction, X-ray photoelectron spectroscopy. The results showed that the crystal of titanium dioxide photocatalyst transformed from anatase/rutile mixture phase to pure anatase phase, and the anatase crystallites size decreased after co-modifying by Ag/Ce⁴⁺/La³⁺. In comparison, Ag/Ce⁴⁺/La³⁺ co-modified titanium dioxide exhibited higher degradation efficiency than that of Ce⁴⁺/La³⁺ modified titanium dioxide and Ag modified titanium dioxide due to the synergistic effect of Ce⁴⁺/La³⁺ and Ag⁰. Moreover, 3% Ag/Ce⁴⁺/La³⁺-TiO₂ coated basalt fiber photocatalyst represented the best activity in the degradation of ammonia nitrogen wastewater. After 6 h degradation reaction, the concentration of ammonia nitrogen decreased from 60.4 mg/L to 2.8 mg/L, and the degradation rate of ammonia nitrogen reached 95.3%, about 74% of total nitrogen was removed during the process, whereas were 93.9 and 70.7% in case of 3% Ag/Ce⁴⁺/La³⁺-TiO₂ powder, respectively.