Preparation And Performances Of Non Thermal Plasma-assisted N-TiO₂ Photocatalysts

Non thermal plasma has become a very promising technology forcatalysts modification,due to its low temperature,high energy,short treatment time and simple operation.In this work,first,N-Ti O2 intermediates was prepared by sol-gel method using urea as the nitrogen source,then,N-Ti O2 photocatalyst was obtained by non thermal plasma-assisted high-temperature calcination treatment under nitrogen atmosphere.The N-Ti O2 catalyst was analyzed by XRD,TEM,EDS,UV-vis DRS and XPS characterization methods,and N-Ti O2 was evaluated under visible irradiation for photocatalytic degradation of methyl orange and acetone gas.On this basis,the discharge characteristics of the dielectric barrier discharge non thermal plasma were preliminary discussed.The research results were as follows.1)The N-Ti O2 photocatalyst was prepared by simple high-temperature calcination in a nitrogen atmosphere,and the optimal calcination conditions determined by UV-vis DRS were as follows:the molar ratio of nitrogen to titanium was 5:1,the calcination temperature was 450°C,and the residence time of N2 was 75 s and the calcination time was 2 h.2)N-TiO₂ photocatalysts treated by“plasma treatment+calcination treatment”,“calcination treatment+plasma treatment”and“calcination treatment”were denoted as N-Ti O2（LTP+C）,N-Ti O2（C+LTP）and N-Ti O2（C）,respectively.The characterization results showed that N-Ti O2（LTP+C）had the smallest crystal grain size（16.3 nm）,the highest nitrogen loading,the best dispersion,and the strongest absorption of visible light,the nitrogen element in the N-Ti O2（LTP+C）existed in the form of replacing nitrogen and interstitial nitrogen.Meanwhile,N-Ti O2（LTP+C）had the best photocatalytic degradation performance for methyl orange solution and acetone gas under visible light.When visible light was irradiated for 240 minutes,its degradation rate for methyl orange solution was88.3%,and it had a good cycle performance.When visible light was irradiated for 7 hours,the maximum degradation rate of acetone gas can reach 50%.On this basis,the reaction mechanism of N-Ti O2 photocatalytic degradation of acetone gas was discussed.When the time sequence of“plasma treatment+calcination treatment”was 20 min（LTP）+100 min（C）,the power was 30 W,and the N2 residence time was 4.2 s,it was the best preparation condition for N-Ti O2（LTP+C）.3)For the studied dielectric barrier discharge plasma treatment device,as the power increased within a certain power range（10～40 W）,the energy density and power output efficiency both first increased and then decreased;within a certain the range of residence time（2.1～8.4 s）,as the residence time of the discharge gas increased,the energy density value gradually increased,while the output efficiency value of power supply was almost unchanged.