Determination of hydrogen peroxide in bleaching streams by a dual-wavelength spectral method

摘要

This study demonstrated a spectrophotometric method for the residual hydrogen peroxides analysis in pulp bleaching streams. In an acidic medium, hydrogen peroxide can instantly associate with molybdate to form peroxymolybdic acid complex that has an absorption peak at 330 nm. To avoid the spectral interference from excess molybdate ion, 350 nm is used for spectroscopic quantification. A linear relationship between the absorption intensity at 350-nm and peroxide concentration was found upto peroxide concentration of about 0.2 mmol/L. It was discovered that the wavelength at 297 nm was an isosbestic point that can be used to develop a dual-wavelength method to account for the spectral interference from dissolved lignin in pulp bleaching streams, a critical procedure for the success of the present method. This method is simple, rapid, sensitive, accurate, and has the potential for on-line applications.