Degradation of tetracycline hydrochloride by ultrafine TiO_(2) nanoparticles modified g-C_(3)N_(4) heterojunction photocatalyst:Influencing factors,products and mechanism insight

摘要

The unique heterojunction photocatalyst of graphite carbon nitride (g-C_(3)N_(4)) modified ultrafine TiO_(2) (g-C_(3)N_(4)/TiO_(2)) was successfully fabricated by electrochemical etching and co-annealing method. However, the effects of various environmental factors on the degradation of TC by g-C_(3)N_(4)/TiO_(2) and the internal reaction mechanism are still unclear. In this study, the effects of initial pH, anions, and cations on the photocatalytic degradation of tetracycline hydrochloride (TC) by g-C_(3)N_(4)/TiO_(2) were systematically explored, and the scavenging experiment and intermediate detection were conducted to better reveal the mechanism on photocatalytic degradation of TC. The results showed that the removal efficiency of photocatalytic degradation of TC by g-C_(3)N_(4)/TiO_(2) could reach 99.04% under Xenon lamp irradiation within 120 min. The unique g-C_(3)N_(4)/TiO_(2) heterojunction photocatalyst showed excellent photocatalytic performance for the degradation of TC at pH 3~7, and possesses outstanding anti-interference ability to NO_(3)^(-), Cl^(-), Na^(+), Ca^(2+) and Mg^(2+) ions in natural waters during the photocatalytic degradation TC process. Superoxide radicals (O_(2)^(·-)) and hydroxyl radicals (^(·)OH) were proved as the main reactive species for TC degradation, and the possible mechanism of the unique photocatalytic system for g-C_(3)N_(4)/TiO_(2) was also proposed. The above results can provide a reliable basis and theoretical guidance for the design and application of visible photocatalyst with high activity to degrade the actual wastewater containing TC.