STUDY ON DEINKING OF MIXED OFFICE WASTEPAPER WITH LACCASE/AMYLASE

摘要

The ink in mixed office wastepaper is difficultly removed because of complex composition of ink as well as existing of adhesive, sizing agent and filler. Since laccase possesses the ability to catalyze and oxidize phenol and aromatic amine compounds as well as amylase can decompose starch, the mixed enzyme of laccase and amylase is used for deinking in this paper. The optimum deinking ratio of mixed enzyme of laccase and amylase was investigated on the basis of the optimum deinking conditions of laccase and amylase that had been obtained in the previous research. The effect of alkaline extract on mixed enzyme deinking was discussed. The results of mixed enzyme deinking were compared with that of chemical deinking. The results indicated that the optimuM laccase to amylase ratio was 40 '. 60.After mixed enzyme deinking, the brightness and the deinking efficiency of deinked pulp were 86.5% SBD and 74.25% respectively. After mixed enzyme deinking followed by alkaline extraction,the brightness of deinked pulp was 92.6%SBD and the deinking efficiency was 92.09%. The brightness and deinking efficiency of deinked pulp increased by 7.1%SBD and 14.23% respectively, the breaking length and tearing Index of deinked pulp increased by 14.72% and 11.31% respectively, the drainage property was obviously improved, the yields were similar as compared with chemical process. The dependability of experiment results mentioned above was confirmed by microscope observation and speckiness analysis.