Preparation of a Z-Type g-C3N4/(A-R)TiO2 Composite Catalyst and Its Mechanism for Degradation of Gaseous and Liquid Ammonia

Abstract

In this study, an (A-R)TiO2 catalyst (ART) was prepared via the sol–gel method, and g-C3N4 (CN) was used as an amendment to prepare the g-C3N4/(A-R)TiO2 composite catalyst (ARTCN). X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), Raman spectroscopy, N2 adsorption–desorption curves (BET), UV–vis diffuse absorption spectroscopy (UV–vis DRS), and fluorescence spectroscopy (PL) were used to evaluate the structure, morphology, specific surface area, optical properties, and photocarrier separation ability of the catalysts. The results showed that when the modifier CN content was 0.5 g, the dispersion of the ARTCN composite catalyst was better, with stronger light absorption performance, and the forbidden band width was smaller. Moreover, the photogenerated electrons in the conduction band of ART transferred to the valence band of CN and combined with the holes in the valence band of CN, forming Z-type heterostructures that significantly improved the efficiency of the photogenerated electron-hole migration and separation, thus increasing the reaction rate. Gaseous and liquid ammonia were used as the target pollutants to investigate the activity of the prepared catalysts, and the results showed that the air wetness and initial concentration of ammonia had a great influence on the degradation of gaseous ammonia. When the initial concentration of ammonia was 50 mg/m3 and the flow rate of the moist air was 0.9 mL/min, the degradation rate of gaseous ammonia by ARTCN-0.5 reached 88.86%, and it had good repeatability. When the catalytic dose was 50 mg and the initial concentration of NH4+ was 100 mg/L, the degradation rate of liquid ammonia by ARTCN-0.5 was 71.60% after 3 h of reaction, and small amounts of NO3− and NO2− were generated. The superoxide anion radical (·O2−) and hydroxyl radical (·OH) were the main active components in the photocatalytic reaction process.

Recent Advances in Synthesis, Characterization and Applications of Innovative Materials in Removal of Water Contaminants

“…The g-C 3 N 4 /(A-R)TiO 2 composite catalyst had a better dispersion, a smaller band gap width, a larger specific surface area, a stronger light absorption capacity, and a stronger photogenerated carrier separation ability than (A-R)TiO 2 catalyst [16]. Gaseous and liquid ammonia were used as the target pollutants to investigate the activity of the prepared catalysts, and the results showed that the air wetness and initial concentration of ammonia had a great influence on its degradation [16]. The superoxide anion radical (O 2 − ) and hydroxyl radical (OH) were the main active components in the photocatalytic reaction process [16].…”

“…The study of Zhu et al [16] on the preparation of a Z-type g-C 3 N 4 /(A-R)TiO 2 composite catalyst and its mechanism for the degradation of gaseous and liquid ammonia is also presented in this Special Issue. The g-C 3 N 4 /(A-R)TiO 2 composite catalyst had a better dispersion, a smaller band gap width, a larger specific surface area, a stronger light absorption capacity, and a stronger photogenerated carrier separation ability than (A-R)TiO 2 catalyst [16].…”

“…The study of Zhu et al [16] on the preparation of a Z-type g-C 3 N 4 /(A-R)TiO 2 composite catalyst and its mechanism for the degradation of gaseous and liquid ammonia is also presented in this Special Issue. The g-C 3 N 4 /(A-R)TiO 2 composite catalyst had a better dispersion, a smaller band gap width, a larger specific surface area, a stronger light absorption capacity, and a stronger photogenerated carrier separation ability than (A-R)TiO 2 catalyst [16]. Gaseous and liquid ammonia were used as the target pollutants to investigate the activity of the prepared catalysts, and the results showed that the air wetness and initial concentration of ammonia had a great influence on its degradation [16].…”

“…Gaseous and liquid ammonia were used as the target pollutants to investigate the activity of the prepared catalysts, and the results showed that the air wetness and initial concentration of ammonia had a great influence on its degradation [16]. The superoxide anion radical (O 2 − ) and hydroxyl radical (OH) were the main active components in the photocatalytic reaction process [16]. The photogenerated electrons in the conduction band of (A-R)TiO 2 catalyst transferred to the valence band of g-C 3 N 4 and combined with the photogenerated holes in the valence band of g-C 3 N 4 , forming a Z-type heterostructure that significantly improved the efficiency of the photogenerated electron-hole migration and separation, thus increasing the reaction rate [16].…”