Research On Biodegradation Of Caprolactam And Nylon-6 Fibre

Nylon-6 is a kind of important fiber material and widely used as engineering plastics. With the application increasing, on the one hand, a lot of nylon-6 waste bring into large white garbage and pollute the environment of our life, and on the other hand, caprolactam, the monomer of nylon-6, is noxious, which can induce the gene mutation of plants and animals. So that some measures should be taken to reduce the pollution of the waste of nylon-6 and caprolactam.In this paper, four strains were selected: ZY, Phanerochaete chrysosporium(P.ch), F4 and flower. Caprolactam was treated with biological method, the kinetics of caprolactam biodegradation was studied and the feasibility of biodegradation of caprolactam and nylon-6 was discussed.The growth character of stain of ZY was studied by testing the absorbency of the culture medium in 420nm. It is indicated that stain of ZY is aerobiosis. In the condition of Ml as the basic culture medium, medium pH, 30°C, 140r/min, stain of ZY can properly growth and can completely degrade caprolactam whose original concentration less than 5g/L in 72hr.Crude enzyme was extracted from stain of ZY. Either the endoenzyme or the exoenzyme has an excellent effect on degradation of caprolactam. By studying the kinetics of crude enzyme degrading caprolactam, it is induced that the Km of crude enzyme extracted from stain of ZY was 6. 25 X10~-3 mol/L. The Km is little, and explains that crude enzyme extracted from stain of ZY has stranger appetency to caprolactam after stain of ZY was domesticated by caprolactam.The biodegradation of caprolactam with P.ch was studied in this research. P.ch can perfectly growth in the basic culture medium M2, phosphate as the buffer (medium or little acid situation). Just as the stain of ZY, P.ch is also aerobiosis and can degrade caprolactam greatly. There are two enzyme systems in P.ch: lignin peroxidases (LiP) and manganese peroxidases (MnP). LiP can improve the degradation of caprolactam with P.ch, otherwise, MnP restrain it. Moreover, mycelium pellet of P.ch has a notable effect on degrading of caprolactam. Thecaprolactam degradation is improved when P.ch was induced by suitable ultraviolet radiation.The oligomer of nylon-6 prepaired by hydrolyzing nylon-6 with hydrochloric acid can be utilized as the only carbon source of microorganisms after domesticated for a long time. Although the membrane of nylon-6 prepaired by phase inversion method cannot be utilized as the only carbon source, the thin membrane was greatly etched by P.ch and F4 when caprolactam was used as the carbon source. Furthermore, P.ch can slightly etched nylon-6 fiber.The biodegradation of caprolactam and nylon-6 lays a foundation for the biologic treatment of waste of nylon-6 and the biologic modification of nylon-6 fiber.