Lignin In Pulping Black Liquor,It's Biological Extraction And Properties

The two substances Lignin and cellulose glue with each other to form the skeleton structure of most plants in nature.It is precisely because of the close integration of lignin and cellulose,making the plants can continue to grow without the cellulose dispersion,which also cast the lignin content in natural a slightly lower than the cellulose content.Stripping from the plant is difficult for lignin.Strong acid and strong base effect in high temperature conditions is used to make the lignin dissoluted in the paper industry.Lignin is existenced in the form of lignin-salt.After acid-base precipitation,lignin solids contain a large number of salt ions which is difficult to remove,which not only affects the yield of lignin,also increases more difficult in lignin modified research and industrial applications.Biotechnology is recognized as the most environmental effect technology,which has considerable value for development.Biotechnology research is also one of the few in the pulp black liquor and the processing of black liquor is still less than ideal,so they need more in-depth researches and practical applications.In this subject,pulping liquor is used as raw materials and the changes of its physical and chemical properties is studied and lignin's change that may be arised in the process with biological treated.The biological treatment can effectively control black liquor pollution of the environment and the development of fully utilized to achieve the maximize use of resources for black liquor.It may enhance black liquor value.The environment of the physical and chemical properties of black liquor is complex,which makes black liquor not suitable for biological processing directly.It often need a treatment to certain conditions for biological treatment,which increases the difficulty of the biological treatment of black liquor.The study found that the main impact of biological bacteria growth factors in black liquor is:high pH,high inorganic salt content,heavy metal ions,tannins and furfural,which have an direct killing effect on biological.The research of black liquor process with Aspergillus niger in this article shows that:Aspergillus niger is good growing in pH ? 9;inorganic salt content ? 7%(mass ratio);black liquor load ratio is 20%(mass ratio).Only when these conditions are content in the meantime,there are external environment for black liquor with Aspergillus niger processing.But fewer nutrients of the black liquor can be directly used by biological bacteria,which can not content the wild type strain of the normal growth,so they need additional nutrients:carbon source,nitrogen source and iron,magnesium,vphosphorus,potassium and other ions.The physical and chemical properties of black liquor has undergone great changes after the processing of the Aspergillus niger in this article.The black liquor pH value dropped to about 3,carbohydrate removal efficiency reaches 93.2%and CODcr removal efficiency reached 77.7%.The distribution of lignin also produce a significant change.Comparing to black liquor without the biological treatment,it is down to the same pH values using dilute acid to adjust pH and the biological treatment black liquor.The lignin content in the former black liquor centrifugal precipitate and the supernatant is 62.6%and 36.8%.The two values respectively reach 89.4%and 5.6%by the treatment of Aspergillus niger,which shows that Aspergillus niger changed the settling properties of lignin and is in favour of the extraction and purification of lignin.It also provide a basis for Aspergillus niger to effectively deal with the black liquor and resource reuse.Drawing lignin after black liquor dealed with Aspergillus niger.the test of ir spectra and function group assay indicated that C=O in lignin was changed significantly after the treatment,the conjugate type C=O was reduced significantly,conjugate type C=O was increased a little.Alcohol hydroxyl and phenolic group content is also reduced.The general trend is not obvious.C-O-C in the ester and the guaiac-based base structure have fracture role and find a new ether is not generated.Through to the content of the function determination it is founded that:content of methoxy group decreased by 2.81%,content of alcohol hydroxyl decreased by 0.31%,content of carboxyl increased by 0.15%.