Study On Bark Of Paper Mulberry Soda Pulping And Its Black Liquor Treatment

In this study,the bark of broad-leaved paper mulberry was used as raw material to produce chemical pulp by Soda pulping process.The paper properties of tissue paper,mixing with bagasse pulp,were discussed.And the characteristics of black liquor were analyzed,and the cooking chemicals were recovered directly by pyrolysis of black liquor,which simplifies the alkali recovery process.A water flow analysis model for wastewater reuse in pulping plant was established and simulated operation and analyzed,providing theoretical basis for the bark of paper mulberry pulping and disposal condition of waste water.The following conclusions are drawn:(1)Through the single factor experiment and the response surface analysis,the optimum technological conditions of the bark of paper mulberry pulping were obtained:Na2CO3 dosage was 15.24%,the cooking temperature was 129.44 ?,time at cooking temperature was 56.27 min,and ratio of material to liquid was 1:5.The optimization results:the yield was 65.23%,kappa number was 12.25.(2)The fiber morphology of the pulp was observed with the microscope,The average fiber length was respectively 8.94 mm and the ratio of length to width was 494.It was high quality fiber material.Through SEM and XRD analysis of the fibers obtained by Na2CO3 pulping and NaOH pulping,It was concluded that the two kinds of fibers have the same structure.And with a small amount of the bark of paper mulberry pulp and bleached bagasse pulp mixing to product tissue paper,the quantitative was 30 g/m2.When the mixture ratio of bark of paper mulberry pulp and bagasse pulp was 25:75,the tear index of paper reached 5.76 mN·m2·g-1,which reached the requirement of the national quality standard of thin page wrapping paper.(3)The analysis of black liquor by elemental analysis,FTIR,GC-MS and TG showed that the organic compounds in black liquor mainly include aromatic compounds,organic acids,ketones,alkanes,alkenes and heterocyclic compounds,which was complex.The chemical structure of sodium carbonate and recycled chemicals was analyzed by FTIR,and their structures were similar.It showed that the main component of the recycled chemicals was sodium carbonate.(4)According to the experimental data,the water balance analysis model of the system was established,and the effluent discharge was calculated.The results showed that there was no wastewater discharge,so the recycling of waste water can be realized.