Effect of Acid Pretreatment on Photocatalysis Bleaching

Abstract

After H2SO4 pretreatment, in unbleached pulps the content of metal ions Mg2+、Mn2+、Fe3+、Zn2+ and Cu2+ are reduced in varying degrees by atomic absorption spectroscopy analysis, among the ions, the maximum removal rates are Cu2+ and Mg2+. And when the added amount of H2SO4 is 1.5%, the removal result of metal ions is the best. After acid pretreatment, the pulp’s brightness has been increased about 3.8%ISO-5%ISO, the pulp’s hardness has been reduced by 0.7%-1.0%, the pulp’s viscosity has been kept well. Besides, when the added dosage of H2SO4 is 1.0%, the increasing of whiteness and the decreasing of hardness are the greatest. Through the contrast research of photocatalysis bleaching to the two pulps of before and after acid pretreatment, the results has been found that the brightness of bleached pulp been decreased about 2.3%ISO-3.5%ISO, and the decreasing rates of hardness and viscosity respectively are almost the same after H2SO4 pretreatment.