Thermo-alkali stable bacterial xylanase for deinking of copier paper

BackgroundThe bleach-boosting capability of xylanases is well-known. The use of xylanase pre-treatment before the application of chemical bleach has multiple advantages including (i) lesser use of polluting chemicals of the traditional bleaching process; (ii) less damage to the cellulosic fibers, therefore better recyclability; and (iii) better brightness of chemical bleach. The major impediment in the application is the availability of commercial enzymes that are active at the elevated temperature and pH that exist during the industrial pulping process. In the present paper, xylanase having suitability for application in deinking is reported.ResultsThe xylanase used showed high deinking potential. Optimal deinking was obtained at the xylanase dosing of 20U/g of the dried pulp at 60celcius for a treatment time of 1h. It could bring about a 50% reduction in the usage of chemical bleach that was applied after xylanase pre-treatment. The comparison of FTIR spectra showed changes in intensity without significant changes in the functional group signatures implying that there is negligible damage to the fiber strength in the xylanase pre-treatment process as compared to the chemical bleach process.ConclusionThe xylanase used in this study was effective in deinking paper pulp and can be used for bio-bleaching of recycled paper.

Automated summary

The xylanase used in this study showed high deinking potential, resulting in a 50% reduction in the usage of chemical bleach. The comparison of FTIR spectra indicated that the xylanase pre-treatment process caused negligible damage to the fiber strength compared to the chemical bleach process.