Study On The Mechanism Of Depectinization Preconditioning Of Whole Cotton Stalk During APMP Process

Higher contention of pectin in the bark of cotton stalk has restricted the application of cotton stalk in the field of pulp and paper making. In this research, a quantitative analysis of metallic ion contentration in the raw material was done by FAAS, and a reasonable model for the following experiments was selected according to the result, the structure and the basic reactive processes of the model was token through AFM,which directed the methods of the depcetinizaton the chemical treatment in the following mechanism research. Sodium hydroxide, sodium oxalate, EDTA-4Na and polyphosphate were taken into account for the research of the "egg box" degradation.Through atomic absorption spectrometry showed that the highest amount of metallic ion in the raw material was calcium ion, which was up to4081.71mg/kg, so calcium was added to form the following research model-Pectate Calcium. From the results of the experiment, including the relationship between the completely dissolved of pectate calcium as well as the speed of response which proved that V’Na2o4>Na5pio10>V NaOH.All of these will promote the degradation of pectate calcium. During the study of kinetic model on the disintegration of Calcium Pectinate Gel, the knowledge of complex titration ISE (Ion Selective Electrode) was used to find the dynamic equation of the CaPG reaction system.Based on the primary analysis about the depectinization preconditioning for the production of whole cotton stalk APMP, the "two stage" chemical treatment was proposed to replace the "three stage" chemical treatment in this paper. A small-scale pilot trial by improving the existing process was carried out in our laboratory, confirming that the technology can be directly applied to the practical production without additional equipment investment.After preconditioning the cotton stalk with32.6g/kg sodium oxalate at90℃, then impregnating and bleaching with56.0g/kg of the total NaOH and96.5g/kg of the total H2O2, the APMP from whole cotton stalk can reach an ISO brightness of70.44%. Further improve the amount of sodium oxalate pretreatment reagent to5.1%,6.6%of the total amount of NaOH,11.4%of the total amount of H2O2, the resulting pulp brightness can reach74.81%.