| The enzymatic and biomimetic bleaching processes are environmentally friendly bleaching techniques. However, the degradation mechanism of polysaccharides and LCC by Laccase and Fe-carboxyl acid(Fe-CA) biomimetic in has not been investigated systematically.In order to understand the chemical changes of polysaccharides of lignincarbohydrates complex extracted from ginkgo, aspen and wheat straw after treated by Laccase/ABTS enzyme system and Fe-CA/H2O2 biomimetic system, carbohydrates in the waste water was measured quantitatively.It is found that free carbohydrates units was released after treated with Laccase/ABTS system and Fe-CA/H2O2 biomimetic system. This indicates the relative serious degradation of cellulose and weak damage on branched hemicellulose and LCC, and the kinds of released monosaccharides are different with enzymatic and biomimetic system from different plants. 0.0201g/L and 0.0649g/L xylose monosaccharides were released in the treatment of Laccase/ABTS system from aspen LCC and ginkgo LCC. Meanwhile, 0.2526g/L glucose monosaccharides and 0.2043g/L xylose monosaccharides was released from wheat straw LCC. These indicates Laccase/ABTS system has a deeper degradation effect with wheat straw than other plants. Whereas, in the treatment of Fe-CA/H2O2 biomimetic system, It is found 0.0249g/L glucose monosaccharides and 0.0325 g/L galactose monosaccharides from aspen LCC, 0.0649g/L xylose monosaccharides from ginkgo LCC, 0.0768g/L xylose monosaccharides and 0.0770 g/L arabinose monosaccharides from wheat straw LCC. Which indicates Fe-CA/H2O2 biomimetic system also has a deeper degradation effect with wheat straw than other plants. Contemporary, Laccase/ABTS system has a deeper degradation effect than Fe-CA/H2O2 biomimetic system. And these carbohydrares unit constitutes LC connections in the LCC, freed monosaccharide may fracture from LC bonds in the LCC.In order to analysis the types and contents of water soluble oligosaccharides in degradation products, the types and contents of oligosaccharides was measured after acid treatment. This indicated that a part of hemicellulose and LCC can be degraded by Laccase/ABTS system and Fe-CA/H2O2 biomimetic system. And the type and contents of olisaccharides fouded in degradation product is much more than monosaccharides. 1.0975g/L olisaccharides was found treated by Laccase/ABTS system and 0.0820g/L olisaccharides was found treated by Fe-CA/H2O2 biomimetic system from aspen. 0.6738g/L olisaccharides was found treated by Laccase/ABTS system and 0.0571g/L olisaccharides was found treated by Fe-CA/H2O2 biomimetic system from ginkgo. 1.5005g/L olisaccharides was found treated by Laccase/ABTS system and 0.6104g/L olisaccharides was found treated by Fe-CA/H2O2 biomimetic system from wheat straw. The analyze the olisaccharides indicates that the degradation effect of laccase/ABTS system is better than Fe-CA/H2O2 biomimetic system for the same kind LCC, and the degradation effect on the wheat staw LCC of laccase/ABTS system and Fe-CA/H2O2 biomimetic system is much better than other LCCs.Wheat straw alkaline pulp treated with laccase/ABTS system or Fe-CA/H2O2 biomimetic system, and combined with EQP bleaching process. It is found laccase/ABTS system and Fe-CA/H2O2 biomimetic system helps to improve the whiteness in the following bleaching process. |
PDF Full Text Request