Enzyme Immobilization And Its Application In Papermaking White-water

In the process of papermaking,white-water recycling can’t only save water and reduce the loss of fiber and cost,but also can prevent pollution and save energy In order to reduce the ATC troubles and improve the fiber forming performance and the times and efficiency of the white-water recycling,the researches which reduces the cationic demand in white-water treatment by immobilized enzyme and compound enzyme is very vital.The paper will use enzyme(pectinase,xylanase,lipase)or compounding to treat white-water.First of all,using chitosan as the carrier and glutaraldehyde as crosslinking agent,the pectinase solution,xylanase solution,lipase solution were immobilized on chitosan respectively.The activity of immobilized enzymes were determined by 3,5-two nitro salicylic acid(DNS).The experimental results showed that the activity of immobilized pectinase reached the maximum 120IU/g when the 2g chitosan was immobilized 16 mL pectinase(concentration was 0.1g/L)and the fixed time was 3h.The activity of immobilized xylanase reached the maximum 220IU/g when the 2g chitosan was immobilized 15 m L xylanase(concentration was 0.1g/L)and the fixed time was 3h.The activity of immobilized lipase reached the maximum 800IU/g when the 2g chitosan was immobilized 15 mL lipase(concentration was 0.1g/L)and the fixed time was 4.5h.The best curing temperature of immobilized pectinase and immobilized lipase was 25℃,the best curing temperature of immobilized xylanase was 30℃.Secondly,the change of the properties of white-water supematant(DCS)was studied after the immobilized enzyme treatment.The results showed that immobilized pectinase,xylanase and i lipase were useful in reducing DCS contents.The pH slightly decreased,and the conductivity increased about 9.7%,the cationic demand(CD)decreased by 52%,the chemical oxygen demand(COD)decreased by 5.2%.The change of DCS was not obvious by immobilized xylanase treatment.DCS was treated with immobilized lipase,pH decreased and conductivity increased,CD decreased by about 25% and COD decreased by 5.5%.Finally,the effect of white-water on the property by the treatment of combination of immobilized pectinase,lipase and xylanase were discussed.The results showed that the optimum ratio of immobilized pectinase,xylanase and lipase was 3:1:2(g/g/g).The pH decreased by 21.8%,the conductivity increased by about 17.5%,CD decreased by 72.8% and COD decreased by 13.2%.The GC-MS analysis showed that the immobilized enzyme could effectively decompose lignin derivatives,unsaturated fatty acids and fatty acids with higher molecular weight.The content of small molecular substances were increased such as aniline,glycerin,propane,benzoic acid and monosaccharide.