MgO作为P-RC APMP高浓停留段部分碱源并替代漂白助剂的研究

Application of MgO as Part of Alkali Source and Substitute for Bleaching Additives in P-RC APMP High Concentration Retention Section

关键词:  P-RC APMP  H₂O₂漂白  MgO取代NaOH  松厚度  纸浆性能

Key Words:P-RC APMP  H₂O₂ bleaching  substitution of NaOH by MgO  bulk  pulp properties

摘要:本研究探究了P-RC APMP高浓停留段MgO替代50% NaOH时，不添加螯合剂DTPA或pH缓冲剂Na₂SiO₃对纸浆性能和漂后残余H₂O₂含量的影响。结果表明，MgO替代50% NaOH后，纸浆的松厚度提高了15.4%，但不透明度和强度性能均下降；不添加DTPA的纸浆比添加DTPA的纸浆松厚度降低了6.5%，抗张指数、耐破指数和撕裂指数分别上升了6.6%、4.4%和6.6%，不透明度上升了10.3%，白度变化不大（增加了0.57%），漂后残余H₂O₂含量为3.55 g/L，降低了5.1%。因此，在松厚度要求不高时，MgO替代50% NaOH作为P-RC APMP高浓停留段碱源可同时替代螯合剂DTPA，即可以免加金属离子螯合剂。

Abstract:The effects of substitution of 50% NaOH by MgO in the high-consistency （HC） stage of P-RC APMP without adding chelator DTPA or pH buffer Na₂SiO₃ on the properties of the resultant pulp and the residual H₂O₂ content were investigated in this study. The results showed that the obtained P-RC APMP has 15.4% increase in bulk but opacity and strength properties decreased after replacing 50% NaOH with MgO. Compared with the pulp adding DTPA， bulk of the pulp without DTPA reduced by 6.5%. However， the tensile index， burst index and tear index increased by 6.6%， 4.4% and 6.6%， respectively. Moreover， the opacity increased by 10.3%， and the brightness had no significant change （only 0.57% increased）. The residual H₂O₂ content was 3.55 g/L at the end of bleaching， which was decreased by 5.1%. Therefore， if the property of bulk was not regarded as most important， using MgO as the alkaline source to replace 50% NaOH in the HC stage of P-RC APMP could also replace the chelating agent DTPA at the same time， thereby the need for metal ion chelating agents was eliminated.