Efficient degradation of tetracycline hydrochloride by Fe2O3 loaded on the surface of halloysite nanotube via photocatalysis and activating peroxydisulfate

Fe 2 O 3 /HNTs composites were prepared by a facile and economical sol-gel method. • Photocatalytic activity of Fe 2 O 3 was greatly enhanced by loading on HNTs surface. • Synergy effect of photocatalysis and PDS activation enhanced TC degradation. • 50 mg FH-40 removed 94.80% of TC molecules within 120 min in Vis/PDS system. • The potential synergistic enhancement mechanism was well proposed. Through loading Fe 2 O 3 on the surface of halloysite nanotube (HNTs), Fe 2 O 3 /HNTs composites (FH-X, X = 10, 30, 40, 50, 70, representing the mass of Fe 2 O 3 in the composite as 10 wt%, 30 wt%, 40 wt%, 50 wt% and 70 wt%), were successfully fabricated via sol-gel method. The effects of Fe 2 O 3 content on the morphology, microstructure, photoelectric and photocatalytic performance of the FH-X composites were systematically investigated. The results indicated that the agglomeration of Fe 2 O 3 nanoparticles was effectively alleviated, which were uniformly distributed on the surface of HNTs and decreased to around 5–15 nm in size. Consequently, FH-X composites exhibited superior adsorption and photocatalytic performance toward tetracycline hydrochloride (TC). With the increase of Fe 2 O 3 content, the degradation of TC by the FH-X composites firstly increased and then decreased. Among them, FH-40 exhibited the optimal photocatalytic performance, which was likely due to the interfacial effect between Fe 2 O 3 and HNTs. The sodium peroxydisulfate (PDS) was used as the auxiliary agent, 0.05 g of FH-40 removed 94.80% of TC (100 mL, 40 mg/L) under visible light irradiation for 120 min in the Vis/PDS system. The reaction rate constant was 4.18 times that of Vis/FH-4. The effects of the PDS and photocatalyst dosage, pH value and initial concentration of TC on the removal rate of TC were also investigated. Additionally, FH-40 exhibited favorable stability, and excellent universality for degrading other organic pollutants. ·SO 4 ⁻ , h ⁺ and ·O 2 ⁻ were the dominant active species during the photocatalysis. The possible degradation pathway and mechanism of TC were proposed. Download: Download high-res image (187KB) Download: Download full-size image Mechanism of TC degradation by FH-40 in Vis/PDS system