Study On Sericin Extraction From Silk Degumming Wastewater And Application

Sericin is one kind of valuable protein resource,it was widely used in food additive, cosmetics, pharmaceutical and bio-material preparation fields. Sericin protein discharged with the silk processing wastewater was not only kind of pollution but also a tremendous waste of resources. Recovering sericin protein effectively, turning waste into treasure is of great significance to the environment and resources recycling.Aiming at the amphoteric characteristics of sericin, the acid analysis results under different conditions were studied. The results showed that sericin was highly extracted and the extraction rate was about 60% under the following conditions:pH=3.8, at 15℃, stirring at the speed of 60 turn/min, the reaction time was 2 hours. The integrated membrane concentration device composed of PVDF hollow fiber ultrafiltration membrane and nanofiltration membrane was designed. The solution could be desalinated and concentrated by ultrafiltration membrane with MWCO6000 (UF6000), and its conductivity (420μs·cm-1) was similar with that of the water(300μs·cm-1). Crude sericin obtained was treated through ion-exchange resin desalting and thin film evaporation and spray drying, thus high purity sericin powder was obtained.Permeated water from ultrafiltration membrane was treated by nanofiltration membrane with MWCO200(NF200), and CODcr of the drain water could meet the national emission standardsⅠfor industrial wastewater, which can be used as cooling water if there was no high demand for electrical conductivity.Sericin extracted was crosslinked on the cotton fabric by BTCA, In this experiment, excellent weight gain and washing fastness of the finished cotton fabric could be obtained under the following condition: 50g/L of BTCA,4% of catalyst (sodium tartrate:sodium citrate 1:1), 10g/L of triethanolamine, curing at 175℃for 120s. The fixation of sericin on cotton fabric was confirmed by SEM and Infrared Red spectra analysis. Cotton fabric finished by sericin could be markedly improved in wear performance added value.