Study On Properties Of Heat Treatment Of Black Liquor

It is difficult to deal with the black liquor of papermaking raw material after cooking, but large amounts of lignin and carbohydrates in black liquor are all available resources. Isolation and purification of lignin in earlier studies are acid precipitation method, and other chemical processing, large amount of complicated process, Extensive use of chemicals, an increase of production costs and with serious pollution, and thus to achieve practical shortcomings is not mature. Because it contains mainly in black liquor is lignin and carbohydrates, If can be the decomposition of lignin and carbohydrate utilization of black liquor pollution basically eliminates.This topic in alkaline pulping black liquor as the research object, the heat treatment of waste liquor, reduce the waste liquor of environmental pollution, more important is the lignin and carbohydrates are cracked into smaller molecules useful or easy to remove the ingredients, research in the process of heating, the changes in the nature of products and properties of lignin and carbohydrates in the black liquor. For this purpose, to find one or more substances as catalyst.The black liquor of heat treatment process parameters were studied. Based on the properties of aluminum chloride in different experiments under pH, heating temperature of the black liquor, aluminum chloride dosage, soaking time, carries on the discussion, formulate a reasonable scheme. The heating temperature is ranging from190℃to320℃, holding time is30minutes. Then the total solids content, ash content, determination of carbohydrates and lignin content of black liquor, and determination of effective alkali content of several groups of the analysis of infrared spectroscopy, UV spectroscopy and lignin.In order to find a method for purification of alkali lignin new separation method in pulping black liquor, using aluminum chloride as the catalyst, high temperature heat treatment of pulping black liquor, to join the change of high temperature heat treatment process of alkaline pulping black liquor properties and aluminum chloride effects on properties of alkaline pulping black liquor. The results show that, in the high temperature heat treatment process, temperature from190℃to320℃, ratio of solids in liquor of from11.84%to11.31%, The carbohydrate content increased from 9.12g.L-1to12.37g.L-1, The lignin content from78.99g.L-1to59.68g.L-1, The pH value from11.29to10.97。When adding a catalyst of aluminum chloride, At200℃with aluminum chloride addition amount from the account for solids content of1%to10%in the course of solids decreased from111.7g.L-1to105.4g.L-1, Lignin decreases from66.20g.L-1to65.97g.L-1, The pH value decreased from11.02to9.87.At320℃, adding aluminum chloride liquor after heat treatment of solids for night ratio of11.11%compared with no aluminum chloride heat treatment of black liquor11.31%low. Compared to12.50g.L-112.37g.L-1high carbohydrate content, ash content higher than44.91%without the addition of aluminum chloride43.64%. The content of lignin59.26g.L-1lower than59.68g.L-1with aluminum chloride. Description of aluminum chloride plays a role in heat treatment of pulping black liquor alkali process, which will provide high temperature heat treatment method for the separation and purification of alkaline pulping black liquor lignin to provide certain theory basis.