Fiber characterization of old corrugated container bleached pulp with laccase and glycine pretreatment

In response to deal with the increasingly serious environmental problems and shortage of fiber raw materials, biological enzyme pretreatment is an effective way to replace a large number of chemical additives to improve the properties of waste paper fibers. Fiber characterization of old corrugated container bleached pulp with laccase and glycine (Lac/Gly) pretreatment was investigated by means of Fourier transform infrared spectroscopy (FTIR), headspace gas chromatography (HSGC), fiber quality measurements (FQA), X-ray diffraction method (XRD), and atomic force microscope (AFM). Results showed that, compared with the control pulp, the whiteness and brightness of the Lac/Gly-treated pulp increased by 16.17% and 7.41%, respectively. And the FTIR showed that Lac/Gly pretreatment promotes the effective removal of lignin by hydrogen peroxide (H₂O₂) bleaching. The content of carboxyl groups in pulp increased remarkably by 21.92%. The paper physical analysis showed that the paper strength properties have improved remarkably. The fiber quality analyses indicated that the fiber length, coarseness, and curl index changed a little. The XRD analysis showed that the crystallinity decreased by 5.83% due to Lac/Gly treatment. The AFM analysis showed that through Lac/Gly treatment, the lignin and extracts over the fiber surface are decreased significantly.