Study On Enzymatic Polymerization Of Lignin And Polysaccharide In Effluent Of Chemi-mechnical Pulping

Effluent from pulping and papermaking process has become a serious problem in the development of papermaking industry, Wastewater from chemi-mechanical pulping system is also difficult to treat. The effluent from APMP process has characteristics of high concentration of phenol compounds , with high content of poisonous and poor biodegradation ability.In this research work, a novel method for APMP effluent treatment was developed. Through dehydrogenation co-polymerization reaction of p-hydroxycinnamic acid and lignin, the water-soluble lignin in efficient could be removed efficiently. Many researches were carried out about the mechanism of dehydrogenation of co-polymerization reaction of p-hydroxycinnamic acid with lignin model compounds, and the soluble lignin and polysaccharide separated from the effluent. The p-hydroxycinnamic acid were used to reacted withβ-O-4 type,and phenolic 5-5'type lignin model compound, and the soluble lignin and polysaccharide isolated from waste water. Then, the experimental conditions for the treatment of APMP effluent was optimized. The use of polymerzation treatment of the effluent was also discussed.In this reaearch, the lignin model compound ofβ-O-4 type, phenolic 5-5'type were synthesized, The p-hydroxycinnamic also be prepared. The soluble lignin and polysaccharide were isolated from APMP effluent. The synthesis method of lignin model compound was improved.The obtained products were analyzed by FT-IR, 13C-NMR .In this research, polar microscope, GPC were used to understand the extent of polymerization. The FT-IR and 13C-NMR spectroscopy were employed to determine the chemical structure of the polymer obtained. Then the mechanism of polymerzation catalzed by laccese between the p-hydroxycinnamic acid and APMP effluent was ananlyzed.It was shown thatβ-O-4 type lignin compound could be co-polymerized with p-hydroxycinnamic acid catalyzed by laccase. While GPC determination proved the molecular weight Mn increased from 320 to 3105. The polymer yielded contains association ofβ-O-4,α-O-4,β-β,β-5,5-5 structures. The result indicated that dehydrobivanillin (phenolic 5-5'type) could polymerize with p-hydroxycinnamic acid catalyzed by laccase. While GPC determination indicated the molecular weight Mn increased from 306 to 2106. The polymer yielded mainly consist ofβ-O-4,α-O-4,β-β structures.It was found that p-hydroxycinnamic acid could be co-polymerized with water-soluble lignin of APMP effluent catalyzed by laccase, GPC determination proved the molecular weight Mn increased from 3190 to 24527. The obtained polymer mainly consists ofβ-O-4,α-O-4,β-β,β-5,β-1 structures. Moreover, the p-hydroxycinnamic acid could polymerize with polysaccharide of APMP effluent catalyzed by laccase. GPC determination proved the molecular weight Mn increased from 3812 to 7853.Through the dehydrogenation co-polymerization reaction of p-hydroxycinnamic acid and lignin/polysaccharide, the water-soluble lignin and polysaccharide in APMP effluent were removed efficiently. The results showed that both chroma and the concentration of lignin were reduced significantly. The optimum conditions were as follows: p-hydroxycinnamic acid dosage 0.066g/L, laccase dosage 14.82IU/L, temperature 25℃, reaction time 2h. The concentration of lignin was reduced by 73.9%, the concentration of polysaccharide was reduced by 37.9%. CODCr could be improved by 69.1%. About 86.7% of chroma also removed.In this research the produced sludge from co-polymerization reaction of p-hydroxycinnamic acid and lignin/ polysaccharide of APMP effluent were added to corrugated medium. It was shown that the tensile index and burst index of the paper increased if the added sludge was leee than 5%. The optimal dosage of sludge was 4%. Under this condition, the tensile index and burst index of the paper improved by 13% and 20%.