Degumming With Acids And Enzymes And Pretreatment Of Citric Acid Degumming Wastewater

Silk fibers were degummed by five different agents: citric acid, tartaric acid, sulfuricacid, papain and2709alkaline protease. Several factors of degumming agents asconcentration, temperature, reaction time and bath that would affect the degumming effectwere discussed, degumming effects of several different degumming agents were compared,and the optimum technological conditions of different degumming agents theabove-mentioned were obtained. The experiment showed that the optimal technologicalconditions for degumming with several acid were as follows: citric acid15g/L, degummingtemperature98℃, bath ratio1:60, degumming time30min; tartaric acid6g/L, degummingtemperature98℃, bath ratio1:60and degumming time30min; sulfuric acid6%(volumefraction), degumming temperature98℃, bath ratio1:60, processing silk45min. A optimumprocess on the enzyme was as follows: papain18g/L, reaction temperature85℃, or2709alkaline protease15g/L, reaction temperature45℃. Both the reaction time was60min,bath ratio1:50. Under the condition of optimal process, the damage degree of silk would bereduced and be beneficial to the subsequent printing and dyeing processing. In addition,other properties of the silk were almost unaffected.The dyeing performance of silk that degummed with different degumming agent theabove-mentioned was also discussed. And the test was performed by Weak Acid Red GNand Weak Acid Brilliant Blue R. The results showed that the dyeing rate on the silkdegummed with citric acid and tartaric acid was higher than silk degummed with papainand2709alkaline protease, if silk was dyed directly with two kinds of dyes. However, ifusing acetic acid to adjust pH of dye bath and using sodium sulphate to promote dyeing,the dyeing rate on the silk degummed with two kinds of enzymes also reached about98%.Generally speaking, degumming water of the silk is difficult biodegradable. Thearticle took wastewater of silk degummed with citric acid as an example, and the wastewater was pretreated with physical coagulation method. COD removal rate reached54%when the wastewater was treated with concentration of twelve hydrated aluminumpotassium sulfate (Alum)3000mg/L. Polyacrylamide (PAM) can play the role ofcoagulation aid when the flocculant is polyaluminium chloride (PAC). COD removal ratecould reach61%when the concentration of polyaluminium chloride (PAC) was2200mg/Land the concentration of polyacrylamide (PAM) was400mg/L.