The effect of interaction in ionic liquids on diffusion coefficient of nitrobenzene was investigated with ultraviolet spectroscopy and cyclic voltammetry.The results showed that compared with the ultraviolet spectrum in cyclohexane and water

red shift effect of absorption peak of nitro group was observed in EMimBF4(1-ethyl-3-methylimidazolium tetrafluoroborate)

and no end absorption was found when the wavelength was smaller than 210 nm

while the absorption of benzene ring had little change.These phenomena could be ascribed to the strong interaction between EMimBF4 and nitro group.The interaction between EMimBF4 and nitrobenzene as well as between EMimBF4and water had a complicated effect on diffusion coefficient of nitrobenzene electrochemically reduced in EMimBF4With increasing concentration of nitrobenzene

diffusion coefficient of nitrobenzene decreased.Increasing the carbon number of imidazolium side chain had a similar effect

but the trend of decrease was slower.At the same nitrobenzene concentration

with increasing water concentration

the value of diffusion coefficient of nitrobenzene increased in the same ILs.In different ILs

at a larger carbon number of imidazolium side chain

increasing water concentration caused a faster trend of increase of diffusion coefficient.