The Biological Enzyme In Applied Research, In The Processing Of Cotton Knitted Fabric Before

Traditional pretreatment process in dyeing and printing, generally, has high energy consumption, uses large amounts of salt and alkaline, and discharges large volmes of water containing various kinds of pollutants, which has caused great harm to water environment. Bio-enzyme technology has high efficiency, saving energy, raw materials and other features, as an alternative of traditional pretreatment, will have a broad application prospects. This research studied bio-enzyme technology in pretreatment of cotton knitted fabric, in order to provide theoretical and technical support for promoting its further application in cotton printing and dyeing industry.Firstly, in this research by measuring the activity of pectinase, cellulase, lipase and protease these four categories of nine kinds of enzymes, the optimal conditions of utilizing single enzyme were determined, and the effects of temperature, pH on the enzyme activity were investigated. Under these conditions, the study examined scouring effect of the single-enzyme and complex enzymes by comparasion of the fabric pectin removal, wetting, and strength loss. Tests showed that the scouring effect of alkaline pectinase BioPrep3000L was far superior to acidic pectinase PL-300, and the alkaline pectinase scouring effect was improved by adding an appropriate amount of cellulase 963,but adding lipase, protease could not improve the scouring effect of pectinase BioPrep3000L and even had a negative impact. So the recipe for the complex enzyme should contain mainly alkaline pectinase and cellulase supplemented. Furthermore, through the response surface method, optimization of process conditions was determined, the result showed that pH between 8-9 only had minor fluctuations in pectin removal with the pH changes, and pectin removal gradually increased as the temperature decrease from 65℃to 55℃.Considering of the effect of temperature on the alkaline pectinase activity, and the results of other researchers, the optimum temperature of complex enzyme scouring is 55℃;Pectin removal rate significantly increased with the processing time prolonging and enzyme dosage enhanced. In addition, using software to optimaze the respond value and analyze the contribution of various factors on pectin removal efficiency, finally, the optimum process conditions was recommended:pH 8.5(1/15M NaOH/NaH2PO₄),55℃,the processing time 35 min, Alkaline Pectinase 0.03% (o.w.f), cellulose 963 0.1 g/L,JFC 0.2 g/L, bath ratio of 1:20, test validated average pectin removal rate is 75.0%, attaining a more satisfactory scouring effect.Secondly, this study also examined the effects of penetrants, chelating agents, and ionic strength on enzyme scouring effect with pectin removal measured, the research results shows that penetrant in bio-scouring is essential, and non-ionic surface active agent (JFC) is perior to the ionic surfactant, and chelating agents (EDTA) makes for bio-enzyme scouring, which the best results acquired when the dosage of 0.05 mmol/g substrate; ionic strength (K2HPO₄ dosage) is of great benefit to pectin removal. At the same time the relationship of the pectin removal with alkaline pectinase usage and processing time was studied, and found the function y=αX^b fits the pectin removal very well. Furthermore, the results also found that complex enzyme dosage, K2HPO₄ (buffer salt) usage and the processing time were of its greatest impact, so these three factors orthogonal to select the best application process as follows:Alkaline Pectinase BioPrep3000L 0.05% (owf), cellulase 963 0.1 g/L, K2HPO₄ 2 g/L, the processing time 30min, pH 8-9,55℃.The process can achieve 75% removal of pectin, which has reached the production requirements and is the relatively economic.Finally, the pilot-scale trial of enzyme treatment process compared with the traditional alkali treatment effects were performed, and the tests results showed that wetting, whiteness, pectin removal performance and deying ability of fabric by enzyme pretreatment were similar to traditional process, but weight loss rate and the strength loss significantly reduced. From an environmental impact perspective, the displacement of enzyme treatment process compared to the traditional process reduced by 50%, the pH decrease, the biodegradability increased 14.7%, and COD_Cr reduced by 19.7%, it has a good environmental benefits. From the view of cost, relative to alkaline bleaching two-step and the alkali-oxygen one-bath process, the costs of dark-colored cloth with enzyme pretreatment process are reduced significantly, a decline of 63.6% and 54.1% acquired, respectively. The costs of light-colored cloth with enzyme pre-treatment process fell 21.6% compared to alkaline bleaching two-step process, and slightly lower than the costs of the alkali-oxygen one-bath process, but due to big damage on the fabric strength in alkali-oxygen one-bath process, many factories has quitted using this technique. In view of better economic and social benefits using bio-enzyme pretreatment process, so it is a technology worthy of promotion.