308nm光作用下α-Fe_2O_3表面HNO_3的光解

Photolysis of Gaseous HNO_3 on the α-Fe_2O_3 Films Under 308 nm UV Light

采用紫外可见光谱(UV-Vis)、傅立叶变换红外光谱(FTIR)及离子色谱(IC)技术对HNO3在α-Fe2O3表面暗反应和308nm下光解反应进行了研究.考察了时间、HNO3浓度、相对湿度(RH)等条件对反应的影响.结果表明,随着HNO3浓度、光照时间的增加,HNO3在气相与α-Fe2O3表面光解产物浓度均呈指数增加;HNO3在α-Fe2O3表面光解产生的NO2、NO分别为气相产生的3.27及3.87倍,而无论气相还是表面光解的NO2浓度均约为NO的2倍.随着RH的增加,HNO3光解产生的HONO的浓度随之呈指数增大,其产率从RH 20%时的0.023增加到90%时的0.087.α-Fe2O3的表面效应在HNO3的表面光解反应中起主导作用.

Under 308 nm UV light, photolysis of HNO3 in the gas phase and on the α-Fe2O3 films was studied by using ultraviolet- visible spectrophotometer （UV-Vis）, Fourier transform infrared spectrometer （FTIR） combined with ion chromatography （IC） technique. The effects of HNO3 initial concentration, relative humidity （RH） and illumination time were systematically investigated. Results showed photolysis of HNO3 could produce NO2 and NO in the gas phase and on the α-Fe2O3 films. With the increase of reaction time and HNO3 initial concentration, the concentration of NO2 and NO were all increased exponentially. NO2 and NO concentrations produced from photolysis of HNO3 on α-Fe2O3 films were about 3.27 and 3.87 times higher than those in gas phase, respectively. And NO2 concentration was about 2 times higher than that of NO whatever photolysis of HNO3 in gas phase or on α-Fe2O3 films. HONO concentration increased in exponent regularity along with the increase of RH. The yield of HONO increased from 0. 023 to 0. 087 when RH from 20% increased to 90% . Surfaces effect played a leading role in photochemical reaction of gaseous HNO3 on the α-Fe2O3 films.