On the basis of the solution of acetaldehyde oxidated by nitric acid for production of glyoxal,the pigment concent ration of the glyoxal solution was presented by absorbance that was measured.Based on experiments,257 nm was the most suitable wavelength for measuring absorbance of the solution and the equation was obtained to compute pigment concent ration by absorbance,and adsorption isotherm were obtained.The effects of various parameters such as the temperature and time have been investigated.The results shows that the optimum conditions were 60℃ solution temperature,pH=2.0,7% amount of active carbon,and 60 min process time.About 78% of the discoloration ratio was obtained.The colourity of production could meet the requtiment.
