Thermal Stability Of Pectinase And Its Application In Bioscouring On Cotton Fabric

Alkine scouring process for the cotton fabrics is generally used in the printing and dyeing factory. The process has the disadvantages as high energy consumption, time consumption and environmental pollution, differs widely from the needs of energy-saving emission reduction for the textile finishing, and is not a kind of environmental friendly process. Biological enzyme possesses the properties of high efficiency, specificity and mild function conditions. The scouring process using biological enzyme instead of alkaline meets the basic requirements of energy-saving emission reduction. Pectinases have been proven to be the most effective for cotton enzymatic scouring in all kinds of enzymes. Pectinase can be effectively used in the refining treatment for the cotton fabrics. However, pectinase is a kind of active protein which has the inactivation behaviors at high temperature. The characteristic of pectinase becomes the bottle-neck of the application. If pectinase can be used at high temperature in the scouring process, the processing time will be greatly shortened. This will not only meet the needs of continuous production, but also improve the economic benefits. As a result, it has the environmental and economic significances to study the thermal stability of pectinase and its application in bioscouring on cotton fabrics at high temperature.This paper was mainly divided into two parts. The first part studied the pectinase’s thermal inactivation kinetics as well as the influences of surfactants on its thermal stability of pectinase. And the second part investigated the application of pectinase in bioscouring on cotton fabrics.Firstly, the thermal inactivation kinetics of pectinase was investigated by DNS method. The thermal inactivation kinetics of pectinase in solution and on cotton fabric was compared to study the influence of cotton fabric structure on the thermal stability of pectinase. Meanwhile, the effects of surfactants on the thermal stability of pectinase for cotton fabrics were also studied. The results showed that the thermal inactivation kinetics of pectinase conformed to the first order reaction model. The thermal stability of pectinase on cotton fabric was better than that in solution at the same temperature. In solution, the half-life of pectinase was90min at60℃,1.25min at70℃, and0.2min at80℃. The inactivation rate was so fast. On cotton fabric, the half-life of pectinase was118min at60℃,11.1min at70℃, and4.1min at80℃. The tea saponin belongs to triterpene saponins and is composed of heteroside, aglycone and organic acid. When the tea saponin was added, the half-life of pectinase on cotton fabric was improved to certain degree. The ingredient of triton is polyoxyethylene-8-octyl-phenyl ether. The ingredient of peregal O is fatty alcohol-polyoxyethylene ether. The peregal O or triton had little effect on the half-life of pectinase. The tea saponin improved the thermostability of pectinase while peregal O and triton had little effect on that of pectinase.Secondly, the application of pectinase in bioscouring on cotton fabrics was studied. The effects of padding process and dipping process were compared. And a kind of surfactant which could improve the scouring effect was selected. The single factor analysis method was adopted to find optimum refining conditions of temperature, incubation time and enzyme concentration. The biosouring process at high temperature was explored, and the effects of enzyme scouring were compared with that of alkali scouring process. The results showed that padding process is better than dipping process. The tea saponin could improve the scouring effect. The optimal process conditions for bioscouring on cotton fabrics were as follows:padding with pectinase using a material to the liquor ratio of1:30, the concentration of pectinase is1g/L, the concentration of tea saponin is1.5g/L, the pH value is8, the treated cotton fabrics is carried out in temperature-controlled shaker at70℃for15min. This process could shorten the scouring time from1-24hours to15min, increasing the productivity. Compared to alkaline scouring, the processing condition of pectinase scouring was mild, could remove part of wax, and had little injuries for cotton fibers. It could achieve the similar scouring effect as the conventional alkaline scouring only in15minutes. The processing condition of alkali scouring is bad. It will cause the large reduction of cotton fibers, injuring the fibers. Accordingly, pectinase refining has very good development prospects.Finally, the padding scouring process at normal temperature (30℃), middle temperature (60℃) and high temperature (70℃) were compared. The diferences of time needed for the similar processing effects (pectin remove rate above90%, weight loss rate above1.400%) under these conditions were studied. The results showed that the increasing temperature could shorten the processing time of pectinase, increasing the productivity. In order to achieve the same effect, under these conditions, a desired pectin removal rate companied with adequate weigh loss was reached. That is padding with pectinase at30℃for60min, padding with pectinase at60℃for30min, padding with pectinase at70℃for15min.