The Research On Bleaching Of Wheat Straw Pulp With The Enzyme Of Saccharomonospora Viridis

The results of previous studies of Saccharomonospora viridis' producing law showed that, the xylanase from Saccharomonospora viridis had the characteristics of alkali tolerance and high thermal stability and displays predominance in biological pretreatment of pulp bleaching. Therefore, Saccharomonospora viridis were selected as experiment strains in this article and be researched on fermentation condition in depth. The enzymes from Saccharomonospora viridis were used in wheat straw soda-AQ pulp bleaching and bleaching mechanism was studied. Conclusions were as follows:(1) Saccharomonospora viridis couldn't produce Hight lignin peroxidase activity and xylanase simultaneously with wood flour unextraced as inductor; could produce the two enzymes simultaneously with wood flour extraced as inductor(2) The effect of wheat straw pulp as inductor on the activity of the produced lignin peroxidase was the best, and the activity of the produced lignin peroxidase is up to 0.31U/mL in the 5^th day. Chinese white poplar extracted was also better inductor, and the result of producing enzymes in the 5^th day was lignin peroxidase 0.22 U/mL, xylanase 4.08 U/mL and cellulase 1.04U/mL. Therefore, wheat straw pulp and Chinese white poplar extracted could be took as further studies object.(3) Wheat Straw Soda-AQ pulps were treated by the enzyme of Saccharomonospora viridis. An optimum process of enzyme treatment could be the enzyme dosage of 20U/g, pH 7.0, the pulp consistency of 10%, the treating temperature of 60℃C and the treating time of 120 minutes. Wheat straw pulp was bleached in this condition with the enzyme. The brightness of bleached pulp rose6.8%ISO, the Kappa value dropped 1.9, and the viscosity was increased. Treated with xylase and few cellulase, the viscosity of bleached pulp could be increased, compared to the enzyme free cellulase.(4) Compared to the contrast pulp, when the pulp was treated by enzyme, the content of pentosan reduced 1.99%, the content of xylose decreased by 1.10%, the content of arabinose decreased by 0.98%, the content of glucose increased 2.08%. Above all, when the enzyme was used in the treatment process, the main degradation was xylan and arabin, cellulose was degraded relatively little.(5) According to the result of X-ray Diffraction (XRD), the crystallinity of the biobleached pulp was higher than the unbiobleached pulp. This was because the enzyme mainly reacted in the anarchic field of fiber.(6) The effect of DED was increased obviously after enzyme processe, the brightness of the bleached pulp rose 17.4%ISO. DED and XDED pulp was analyzed by infrared spectra. Compare to DED pulp, the strength of carbonyl and benzene ring was decreased in XDED pulp. The results showed that the content of chromophoric group and lignin in bleached pulps was decreased by enzyme process.