Study On Fenton Oxidation Delignin Short Sequence Bleaching Of Sofewood Kraft Pulp

With the continuous development of paper industry towards the direction of green environmental protection,short-sequence chlorine free bleaching is gradually replacing the traditional chlorine containing bleaching process,and is widely used in pulp and paper industry production。Fenton oxidation technology has developed rapidly in papermaking wastewater treatment and pretreatment of unbleached pulp due to its strong oxidizing properties of hydroxyl radical。In this paper,a new short-sequence bleaching process of softwood sulfate unbleached pulp was studied by Fenton oxidation,followed by alkali extraction and hydrogen peroxide bleaching。In this paper,a new short-sequence chlorine-free bleaching process of softwood sulfate unbleached pulp was studied by Fenton oxidation,followed by alkali extraction and hydrogen peroxide bleaching。The effects of dosage of hydrogen peroxide,dosage of ferrous sulfate,reaction p H value,reaction temperature and reaction time on fenton oxidation removal of residual lignin from coniferous wood sulfate without bleaching were studied。According to the change of kber value and fiber degree of polymerization,the suitable process is as follows:pulp concentration was 10%,hydrogen peroxide dosage was 2%,ferrous sulfate dosage was 1%,reaction p H value was 5,reaction temperature was 25℃,reaction time was 60 min。Under these conditions,the kappa value of the pulp obtained after Fenton oxidation and delignin was 9.42,which decreased by 51.23%and the degree of polymerization was 907。The paper pulp after Fenton oxidation delignin was used as raw material to carry out alkali extraction treatment。Through investigating the influence of sodium hydroxide dosage,extraction temperature and extraction time on the subsequent bleaching effect of paper pulp,it is confirmed that the appropriate conditions are as follows:pulp concentration was 10%,sodium peroxide dosage was 3%,extraction temperature was 40℃,extraction time was 60 min。By studying the effects of hydrogen peroxide dosage,sodium hydroxide dosage,reaction time and reaction temperature on hydrogen peroxide bleaching effect,the sui Table process conditions are as follows:The slurry concentration was 10%,the dosage of H₂O₂was 6%,Na OH was 1.5%,EDTA was 0.5%,MgSO₄was 0.1%,the reaction time was 180min,the reaction temperature was 90℃。The kappa value of pulp was 5.21,the whiteness was 78.5%ISO and the degree of polymerization was 721。PFI treatment was carried out to improve the physical properties of the bleached pulp。When the beating revolution was3000r,the beating degree was 35° SR and the breaking length was 4.2km,which could meet the requirements of co mmon culture paper in paper whiteness and breaking length。It was found by fiber analyzer and scanning electron microscope that the fiber surface became rough,peeling,uneven and collapsed。The results of FTIR showed that the benzene ring and side chain structure of lignin were destroyed and the lignin structure was degraded and dissolved。...