Study Of Alkali Lignin Separation And Utilization Of Crude Tall Oil Waste

There are rich pine resources such as masson pine in southern China,which is often used as a raw material for pulping and papermaking.As the pine mainly contains many components such as cellulose,lignin,hemicellulose and resin,a large number of by-products such as tall oil,sulphate turpentine,alkaline lignin(black liquor)in the process of alkali cooking pulping are produced,the tall oil,which is also known as suspended oil on the woody pulp,mainly contains resin and fats,so it is very important chemical raw material,and it is used in many industries such as mineral processing,paint and soap making.Most of the tall oil in the world is produced by U.S.A,although the development and utilization of tall oil in China started late,but it is developing fast,and the annual output of crude tall oil is gradually increasing.Lignin is a natural polymer material,second only to cellulose,and is one of the most important renewable resources in the world.The source of lignin is very wide,and more than 50,000,000 tons of lignin is produced annually in the cooking liquor of pulping and papermaking industry.The structure of lignin is complex and varied,and there is a variety of functional groups in lignin,and lignin has many uses.The cheruically modified products of lignin can be used as concrete water-reducer,asphalt emulsifier,cement grinding agent,dye dispersant,additive for coal water slurry,pesticide release agent etc.In the separation process of tall oil,by-product of pine pulping,crude tall oil residue about 15%of tall oil yield is produced,and the main components in the crude tall residue are tall oil and alkali lignin,and the residue has not been effectively separated and utilized until now.The optimum process conditions for separation of tall oil and alkali lignin in crude tall oil residue,and the optimization process conditions for the chemical modification of the separated alkali lignin to be dye dispersant were studied in this paper.Separation process of tall oil and alkali lignin in crude tall oil is as follows:first the crude tall oil residue is saponificated,second it is salted out and filtered,third it is acidified,through above process,the crude tall oil and alkali lignin can be separated from the crude tall oil residue,and the acid value of the separated crude tall oil can reach to the second corporation standard.In the modification process of alkali lignin to prepare dye dispersant,the effect of four modification methods of alkali lignin including sulfonation,oxidized sulfonation,sulfomethylation,and oxidized sulfomethylation on the dispersing performance of the dye dispersant from alkali lignin was discussed and compared,the results indicated that the dispersing effect and thermal stability of the dye dispersant from the alkali lignin through oxidized sulfomethylation was the best among the four modified products.The optimum modification process conditions of alkali lignin through oxidized sulfomethylation is as follows:the oxidation temperature 600C,oxidation time lh,hydroxymethylation temperature 750C,hydroxymethylation time lh,the mass ratio of formaldehyde to alkali lignin 2.9:5,sulfonation temperature 90'C,sullfonation time 5h,the mass ratio of to alkali lignin 0.5:l,and the results showed that under this optimized conditions,the dispersing performances and thermal stability of the modified alkali lignin can meet the requirements of dye dispersant.