Post-harvest treatment of carbendazim in Chinese chives using TiO(2)nanofiber photocatalysis with different anatase/rutile ratios

摘要

Carbendazim residues in Chinese chives were treated by photocatalysis using the following three electrospun TiO(2)nanofibers: TTiP/PVP, TTiP/PVAc, and TBOT/PVP. The as-spun fibers were calcined at 500-650 degrees C to achieve anatase/rutile (A/R) ratios of 100:0, 80:20, 70:30, 50:50, and 30:70. The obtained anatase crystallite sizes were in the range of 13.9-28.1 nm, while the rutile crystallite sizes were 21.1-30.6 nm. The experiments were conducted in glass reactors. These were filled with water and each type of the fiber and irradiated from above by black light lamps for 5 min. Then, 50 g of the samples of Chinese chives was immersed for 5, 15, 30, and 60 min. Carbendazim in the chives was extracted using the matrix solid-phase dispersion (MSPD) method and analyzed using UHPLC. The & x2d9;OH formation from each fiber type was investigated using the coumarin fluorescent probe method. An A/R ratio of 70:30 yielded the highest & x2d9;OH formation, as well as the greatest carbendazim degradation. Rutile plays a crucial role in inhibition of electron-hole recombination and & x2d9;O(2)(-)stabilization. The degradation efficiencies for carbendazim from TTiP/PVP, TTiP/PVAc, and TBOT/PVP fibers after a 60-min treatment were 98.6-99.5%, 91.2-97.1%, and 99.5-99.9%, respectively. The TTiP/PVP and TBOT/PVP fibers produced levels of retained carbendazim in the chives that were within EU maximum residue limits of 0.1 mg/kg. The thermal stability of the TTiP/PVAc fiber limited & x2d9;OH formation and carbendazim degradation.