Ozone Treatments of Bleached Krft Pulp and Wastepaper II - Simultaneous Use of Ultraviolet Lights and Hydrogen Peroxide during Ozone Treatment of Bleached Kraft Pulp -

摘要

In a previous report, it was found that the brightness and the sheet strength tended to be improved when the chlorine compound component included in the pulp decreased during the ozone treatment of the chlorine-type bleached pulp. At this time, ultraviolet lights and hydrogen peroxide were simultaneously used during the ozone treatment of the bleached kraft pulp as an application of the advanced oxidation process. The effect of the treatment by each combination of ozone/ultraviolet lights, ozone/hydrogen peroxide, and ozone/ultraviolet lights/hydrogen peroxide on the various physical properties of the pulp fiber and the changes in the chlorine compound in thepulp were examined. In this experiment, three kinds of light sources with different wavelengths and outputs were used as sources of the ultraviolet lights, and changes in the reaction condition such as the amount of addition of hydrogen peroxide and the presence of the stabilizer, etc., wre evaluated. The total halogens (TX) and the ethanol extractable organic halogens (EOX), which were the index of the chlorine compound, freeness, water retentiuon value, limiting viscosity number, tensile strength, and light scattering coefficient, etc., of the sample were measured after the treatment. Both the total halogens (TX) and ethanol extractable organic halogens (EOX) decreased compared to the value by the ozone treatment alone when the pulp was treated by the ozone/ultraviolet lights combination. On the other hand, the brightness and tensile strength were significantly improved when the pulp was treated with the ozone/hydrogen peroxide combination. For the combination of ozone/ultraviolet lights/hydrogen peroxide, the tensile strenth was remarkably improved. Moreover, it was found that the improvement in the sheet strength by the ozone tratment was attributed to an increase in the bonding strength between the fibers as a result of the tensile strength and the zero-span tensile strength measurement of the handsheet after the treatment.