Synthesis Of Bi₂O₃-based Nanofibers And Their Photocatalytic Denitrification Performance Of Fuel Oil

With the increasing awareness of the environment,countries around the world have put forward stricter requirements on the nitrogen content of fuel oil.Photocatalytic technology has become a potential deep denitrification method because of its advantages of low cost,clean and high efficiency.In this contribution,Bi₂O₃ nanofibers,Pd/Bi₂O₃nanofibers and BiFeO₃/Bi₂O₃ heterojunction nanofibers were synthesized via a facile electrospinning and subsequent calcination process,and the photocatalytic properties of the obtained nanofibers were systematically investigated by using pyridine/petroleum ether solution as a simulation oil.Main research contents and results are as follows:Firstly,the influences of PAN concentration,Bi?NO₃?₃ concentration,spinning voltage,receiving distance and injection flow rate on Bi₂O₃ nanofibers were studied.The results showed that when the PAN concentration was too low,the fiber could not form but reached the receiving device in the form of water droplets,and when the concentration was too high,the fiber diameter increased.With the increase of Bi?NO₃?₃ concentration,the fiber diameter decreases and then increases,which can be explained by the electric field force and surface tension.The factors of voltage,receiving distance and jet flow rate are also cannot be ignored.When PAN concentration is 10 wt%,Bi?NO₃?₃ concentration is 0.06g/mL,the voltage is 16 kV,the receiving distance is 15 cm and the injection flow rate is 0.2mL/h,Bi₂O₃ nanofibers which obtained with uniform diameter,smooth surface and diameter distribution of about 196 nm.In order to improve the photocatalytic activity of Bi₂O₃ nanofibers,Pd/Bi₂O₃nanofibers were synthesized,and the effects of Pd doping on the structure and photocatalytic performance of Bi₂O₃ nanofibers were studied.The results show that the obtained Pd/Bi₂O₃ nanofibers have a stable monocline?-Bi₂O₃ structure and no other phase is observed when the doping amount of Pd is?1.0 at%.Pd doping can refine the crystal size of Bi₂O₃ nanofibers,which is conducive to obtaining photocatalyst with large specific surface area,broadening its optical response range,and significantly improving the photocatalytic activity of the catalyst.When the doping amount of Pd was 0.5 at%,Pd/Bi₂O₃ nanofibers showed the most excellent photocatalytic denitrification performance,and the degradation rate of pyridine under 60 min of light was up to 84.9%.BiFeO₃/Bi₂O₃ heterojunction nanofibers were prepared for further enhancing the photocatalytic capacity of Bi₂O₃ nanofibers and reducing the cost of photocatalyst synthesis.The results show that with the increase of BiFeO₃ content,the band gap of BiFeO₃/Bi₂O₃ heterojunction decreases gradually,and the reduction of the band gap is conducive to widening the spectral response range of BiFeO₃/Bi₂O₃ hollow composite nanofibers,so as to improve their photocatalytic denitrification performance in the visible region.The photocatalytic denitrification activity of the obtained heterojunction hollow nanofibers was the best,when the molar ratio of Bi³⁺:Fe³⁺was 2:1,and the degradation rate of pyridine under 60 min of light could reach 89.6%,which was 40.2%higher than pure Bi₂O₃ nanofibers.Under visible light irradiation,the photodegradation of pyridine by BiFeO₃/Bi₂O₃ heterojunction nanofibers conforms to the first-order reaction kinetics,and the main active substance is h⁺.