Influence Of Different Degumming Methods On Silk Properties And COD Of Wastewater And Treatment Of Degumming Wastewater

Silk is a kind of very important natural protein fiber, it is made of fibroin andsericin mainly. The degumming process is directly related to the quality of the finalproducts, also it is the most serious pollution links in silk processing. It is well knownthat sericin is the main pollutant in degumming water of silk, which is highconcentration organic wastewater. But up to now, sericin wastewater partly handledtogether with dyeing-water, partly let off without handled, which caused greatenvironmental pollution and energy waste.In this study, silk fibers were degummed with sodium carbonate, neutral soap,tartaric acid,2709alkaline proteinase, hot pressurized water and composited additives.The appearance, mechanical properties, whiteness, secondary structure, dyeability andthe value of chemical oxygen demand (CODcr) of wastewater were analyzed throughscanning electron microscopic, tensile strength tester, white tester, infrared spectrometer,color measurement instrument and CODcr measuring instrument to elucidate the effectsof different degumming treatment. Influence factors of silk degumming wastewaterCODcr value were analyzed and discussed. The spun silk degumming wastwater ofactual production was treated by physical-chemical synthesis process. The results ofthese researches listed as follows:Compared with five kinds of different degumming methods, the effects ofdegummed silk include the surface morphology, structure and properties were different.The effects of proteinase and tartaric acid are relatively good. Whiteness of2709alkaline proteinase degummed silk has been greatly improved. The tensile strength ofsilk yarns degummed by all of the methods were decreased more or less, especially hotpressurized water. The molecular conformation estimated by fourier transform infrared spectroscopy stayed unchanged regardless of different degumming methods.Different degumming methods, the same method to different additives, placingtime, washing method, alkaline hydrolysis condition, time and other factors on CODcrof silk degumming wastewater were studyed. Neutral soap, tartaric acid and detergentplay an improtant part in the CODcr value of wastewater. Degummed silk washed withdilution acetic acid showed bright color, but the soap washed silk was a bit yellow.Effects of neutral soap degumming wastewater treated with polymerization aluminumchloride were obvious, the removal rate of CODcr was higher.Physical-chemical method was used to treated spun silk degumming wastewater.A large number of macromolecular protein precipited by acid precipitation, reducing thefollow-up processing burden. Then, the sericin protein organic matte was furtherremoved by flocculation method. Finally, using activated carbon which has awell-developed pore structure and large specific surface area to dissolved organic matterin water, the effluent quality can meet the national discharge standard.