Reseach On Chemical And Enzymatic Deinking Of Laser-Printed Paper

The waste laser-printed paper is considered as the high quality fibers. But the ink is the thermosetting toners which consist of acrylate synthetic polymers. It can't been dissolved in water and saponified by alkali. So the surfactants and enzymes were added to remove inks from the fibers. The deinking treatment of the waste laser-printed paper by using chemistry and enzyme was studied in this research. The deinking effects of the surfactants and the different enzymes were discussed; and the effect of enzymatic combined with chemical deinking was also discussed in this research.The research results were shown as the following:1. The foaming abilities of surfactants, foam stabilities and deinking technology of surfactants were discussed. It was found that LBS was the most suitable for the combination of wash and flotation deinking among the single surfactants, among the tow-mixed surfactants LAE-7:LBS=1:2 and NL-9:LBS=1:2 were the most suitable, and LAE-7:LBS:JL=2:5:3 was the most suitable among the three-mixed surfactants. After chemical treatment, LAE-7:LBS:JL=2:5:3 was the best one to remove non-impact printed ink from the paper.2. When cellulase and hemicellulase were combined, it was found that mixed enzyme was more efficient than cellulase and hemicellulase. The most efficient one was celluloseA combined with hemicellulase. And the most appropriate proportion of celluloseA and hemicellulase was C/X=1/10, the most appropriate dosage was C=1.0IU/g. Different surfactants were added into the mixed-enzyme treatments, the most appropriate surfactant was LAE-7:LBS:JL=2:5:3, the most suitable pH of the mixed-enzyme was 6.2, the 15% consistency of pulp was the most appropriate condition of the mixed-enzyme. Under those conditions the deinking efficiency was more than 92.3%.3. When laccase and cellulose were combined, it was found that mixed enzyme was more efficient than laccase. The most appropriate dosages of laccase and cellulose respectively were 300IU/g and 0.8IU/g, the most suitable pH was 6.2, and the 10% consistency of pulp was the most appropriate. Under those conditions the deinking efficiency was 87.5%.4. The effect of enzymatic deinking combined with chemical deinking was also discussed. In this research two steps of flotations were handled. The technological procedure was: enzyme treatment—flotation—wash—chemical treatment—flotation. It was found that the deinking efficiency was more than 92%, even was 98% at most.