Preparation Of One-dimensional Titania-based Photocatalysts And Studies On The Degradation Of Antibiotics

In the field of medicine and breeding,the use of antibiotics is becoming more and more common.However,a large amount of antibiotics used will not be fully utilized,and a large part of them will be discharged into the natural water in the form of metabolites.Moreover,the current water treatment technology can not completely remove antibiotics in water,although at low concentrations,exhibits potential risks on human health.Photocatalytic technology has been considered as an important strategy for environmental governance and clean energy development due to its environmental friendliness and good economy.With the help of the TiO₂ semiconductor photocatalyst,we can make better use of photocatalytic technology.For TiO₂,the performance enhancement of TiO₂ is limited by the fact that the broad band gap with a 3.2 eV is only responsive to ultraviolet light and the high recombination rate of photogenerated charge carriers.In order to solve this problem,in this paper,the modified TiO₂ nanotube array and TiO₂ nanofibers were synthesized,and the photoelectrocatalytic oxidation and photo-Fenton technology were proposed for efficient antibiotics removal from wastewater.The main results are as follows:(1)P-doped anatase phase TiO₂ nanotube arrays(TNTAs/P)were prepared by a two-step electrochemical anodic oxidation process and followed doping with P by red phosphorus as a phosphorus source.Experiments showed that the P dopants could enhance the optical light absorption and photo-induced carrier separation efficiency and thus improve the photoelectrocatalytic degradation performance.Fluorescence probe detection showed that TNTAs/P(0.75)could produce more hydroxyl radicals to participate in photocatalytic degradation of Tylosin under simulated solar irradiation conditions.By optimizing the phosphorus doping amount,the photocatalytic degradation efficiency of Tylosin by TNTAs/P(0.75)was 3 times higher than that of bare TNTAs.The advantage of this photocatalytic degradation process is that the electrode has good sustainable utilization performance,and the catalyst is easy to be recovered without causing secondary pollution to the water,and it also has good photoelectrocatalytic degradation performance at a low pollutant concentration.(2)Titanate fiber was prepared from titanium dioxide powder by a hydrothermal method.Then,under the protection of N₂,Fe²⁺ions was ion-exchanged with H⁺in the titanate fiber.After drying in the air,Fe²⁺was oxidized in situ to Fe³⁺.At the same time,FeO_x nanocluster modified TiO₂ nanofibers(FeO_x-TNFs)can be prepared by annealing the Fe³⁺modified titanate in a sealed quartz ampoule.The experimental results show that after FeO_x nanoclusters modification,the light absorption ability of FeO_x-TNFs in the visible light region is improved,and the separation efficiency of photogenerated charge carriers is also enhanced.As the active site of photogenerated electrons,FeO_xnanoclusters can realize the Fe³⁺/Fe²⁺cycling transformation,and promote the generation of more hydroxyl radicals with strong oxidation to participate in the degradation process.After 5 h of white LED light irradiation,the FeO_x-TNFs catalyst can achieve 92%of norfloxacin removal.(3)Using anatase TiO₂ nanofibers and FeCl₂.4H₂O as precursors,the Fe-TNFs photocatalyst was prepared by modification of Fe single atom on TNFs in the low temperature liquid molten salt method and the action of strong polarization force.Compared with FeO_x-TNFs catalyst modified by FeO_x nanoclusters,the Fe content of monatomic Fe-TNFs catalyst is only 6%of the FeO_x-TNFs,but the removal efficiency of norfloxacin is similar to that of the FeO_x-TNFs.This is because the monatomic co-catalyst maximizes the density of active sites on the surface of the photocatalyst.Fe-TNFs photocatalyst can degrade about 93%of norfloxacin after 5 h of white LED light irradiation.Photogenerated electrons can realize the Fe³⁺/Fe²⁺cycling conversion,promote the photocatalytic Fenton system to continuously produce hydroxyl radicals,so that the whole degradation reaction continues.