Study On The Effect Of Metal Ions On Bleaching And Colour Reversion Of Bamboo High Yield Pulp

The effect of metal ions on H₂O₂ bleaching and colour reversion of bamboo high yield pulp was studied.The contents included four aspects.Fir -stly,the content of metal ions in epidermis,node,and xylem of Bambus -a Chungii was determinated and was comparied with each other.Secondly, the technics condition of H₂O₂ bleaching was optimized,and the condition included charge of H₂O₂,charge of NaOH,charge of Na₂SiO₃,charge of Mg -SO₄,charge of EDTA,time and temperature.Thirdly,The effect of metal io -ns on H₂O₂ bleaching and colour reversion of bamboo high yield pulp w -as studied.The last one,the dynamics of decomposition of H₂O₂ catalyesed by Cu²⁺.The results of atomic absorption spectrometry showed that the content of metal ions above 60 meshes was more than that during 40～60 meshes for the same part of Bambusa Chungii.The content of Fe,Mn,Na and Ca of node was more than that of epidermis and xylm.The result of SEM-EDAX showed that the content of Si in epidermis was more than that of xylem.The content of metal ions ofparenchymatous cell was higher than that of xylem.The optimum conditions of H₂O₂ bleaching of Bambusa Chungii SCMP were H₂O₂ 8%,pulp consistency 10%,EDTA 0.5%,NaSiO₃ 5%,NaOH 4%,MGSO₄ 0.05%,70℃,2h.The brightness of bleached pulp was 61.8%ISO.Through studying the effect of Mn²⁺,Cu²⁺and Fe²⁺on bleaching and colour reversion of Bambusa Chungii SCMP,it could be found,Cu²⁺led to H₂O₂ decomposing speediest,and H₂O₂ was decomposed slowest by Fe²⁺.However, during the H₂O₂ bleaching,Mn²⁺had higher catalyzing ability for decomposing H₂O₂ than the other two metal ions(Cu²⁺and Fe²⁺),so this three kinds of metal ions should be eliminated during the bleaching process.Finally,the results of two kinds of metal ions blending into pulp showed that Mn²⁺,Cu²⁺and Fe²⁺ co-existence in pulp have no collaboration on H₂O₂ bleaching of Bambusa Chungii SCMP.The results of study on dynamics of decomposion of H₂O₂ by Cu²⁺showed that temperature was very important to the decomposing on H₂O₂.The activation erergy of decomposion of H₂O₂ by Cu²⁺was 101.21kJ/mol.It suggested that Cu²⁺has a catalysis for decomposition of H₂O₂.