Research On PVA-Degrading Enzyme Applied In Desiziing Of Fabric Sized By Polyvinyl Alcohol

PVA-degrading enzyme can be applied to the PVA desizing process of textile industry because of good biodegradability in order to achieve the effect of degrading PVA directly on the fabric surface and reduce the emissions of desizing wastewater.This paper was mainly about fermentation process,the nature of PVA-degrading enzyme,application of enzyme in the desizing process of cotton and polyester-cotton fabric sized by PVA,and ultrasonic technology assisting the PVA-degrading enzyme desizing.The aim was to promote the biodegradability of desizing wastewater while desizing.Fermentation process and the appropriate reaction conditions of PVA-degrading enzyme were studied.The content of PVA decreased from 5g/L to 0.1365g/L,and the activity was 1.973U/mL. The rate of consumption was 97.29%.Time,pH,temperature and PVA concentration have effects on the PVA-degrading enzyme activity and the degradation rate to a certain extent,and the suitable reaction conditions of PVA-degrading enzyme obtained through experiments were:pH=7.0-8.0, T=30℃,PVA concentration 1g/L,reaction time 3h,and degradation rate of PVA was 49.32%at this time.The PVA-degrading enzyme was applied to the desizing process of cotton fabric sized by PVA.The PVA content in desizing solution was 35.78%,which in fabric was 43.53%,and the desizing percentage was 56.47%for 2 hour.Comparing with desized by hot water and buffer,the desizing rate of PVA-degrading enzyme was worse than that of hot water desizing,but PVA could be degraded by desizing of PVA-degrading enzyme.The PVA-degrading enzyme was applied to the desizing process of polyester-cotton fabric sized PVA,while ultrasonic technology was introduced to assist the PVA-degrading enzyme desizing.It was demonstrated that the best conditions were the volume of PVA-degrading enzyme mixing with phosphoric acid buffer solution 7mL,the volume of NaCl with concentration of 30g/L was 2mL,and temperature was 30℃for 1.5 hour.The desizing percentage was 41.06%,and the degradation rate of PVA was 55.87%.The suitable conditions of desizing by ultrasonic assisting PVA-degrading enzyme were the volume of PVA-degrading enzyme mixing with phosphoric acid buffer solution 7mL,the volume of NaCl with concentration of 30g/L was 2mL,the power of ultrasonic was 50%,and temperature was 30℃for 45min.The desizing percentage was 38.12%, and the degradation rate of PVA was 38.85%.PVA-degrading enzyme activity before and after pretreated by ultrasonic was measured in order to examine the influence of ultrasonic power,temperature,ultrasonic time on the PVA-degrading enzyme activity,and the effect of PVA-degrading enzyme desizing assisted by ultrasonic on T/C fabric was analyzed.It is demonstrated that the PVA-degrading enzyme activity was decreased by ultrasonic,and it decreased greatly with the increasing of power,temperature, treating time of ultrasonic.The diameter of PVA became smaller under the function of ultrasonic.Comparing different desizing methods,it was demonstrated that the rate of weight loss and BOD/COD of desizing solution were higher,but the breaking strength,capillary effect and white were lower by Fenton reagent.The effect of hot and NaOH desizing were worse,because the COD value and the damage for fabric were higher.BOD/COD and capillary effect of fabric desized by PVA-degrading enzyme were increasing,while the strength loss and yellowness were lower.The introduction of ultrasonic made better for fabric desizing.