Study On Stripping Method Of Waste Textiles

In the interest of protect the ecological environment,the recycling of resources has become an important means to achieve green development,and the recycling of waste textiles has also been paid attention to.The stripping of waste textiles with high efficiency and low damage is an important link to improve the added value of waste textiles,which needs to be tackled urgently.In this paper,the technological conditions of stripping of cotton fabric dyed with reactive dyes by thiourea dioxide were optimized;the stripping system of sodium borohydride/sodium pyrosulfite was designed,the stripping mechanism of the system was discussed,furthermore,the stripping process of dyed cotton,wool and silk fabric was optimized,and the influence of stripping on the structure and properties of fiber was analyzed.The experiment results showed that the optimum stripping process of cotton fabrics dyed with reactive dyes by thiourea dioxide was as follows:thiourea dioxide 4 g/L,sodium hydroxide 5 g/L,70? and 40 min.Under these conditions,the stripping rate is over 95%,and the retention rate of strength is over 96%.The results of UV-Vis,FT-IR,1H-NMR and XPS show that the color stripping system of sodium borohydride/sodium pyrosulfite can produce active substance(high energy state[H])which acts on the chromogenic group of dye.In the process of stripping,the azo conjugated Chromogenic System in the azo structured dyes was destroyed,and two primary amino groups(-NH2)were produced by breaking;the anthraquinone(C=O)conjugated Chromogenic System in the anthraquinone structured dyes was not completely destroyed.The optimal optimization stripping process for cotton fabric dyed with reactive dyes was as follows:the B component was 1.5%(o.w.f),the B/S mass ratio was 1:3.2,the pH value was 13.5,the temperature was 100? and the time was 5 min;the optimal optimization stripping process for silk fabric dyed with acid dyes was as follows:the B component was 2%(o.w.f),the B/S mass ratio was 1:2.2,the dosage of sodium carbonate was 0.5 g/L,the temperature was 100? and the time was 5 min;the optimal optimization stripping process for wool fabric dyed with reactive dyes was as follows:the B components of azo and anthraquinone structure were 3%(o.w.f)and 1%(o.w.f),respectively,the mass ratios of B/S were 1:3.4 and 1:2.8,respectively,the temperature was 100? and the time was 10 min.Sodium borohydride/sodium pyrosulfite stripping system can complete stripping most of cotton fabrics dyed with reactive dyes and silk fabrics dyed with acid dyes;anthraquinone dye reactive blue KN-R and pula brilliant blue RAWL undergoes two-step treatment with hydrogen oxide and nicotine AN respectively,its stripping rate has been greatly improved,while the strong retention rate was reduced,furthermore,the whiteness value was close to the original fabric;the K/S values and color characteristic values of the fabrics had slightly difference after counterstaining of stripped fabrics.Compared with the conventional method,the system of sodium borohydride/sodium pyrosulfite not only has high stripping rate and low loss of strength,but also has less reagent and short stripping time.It is a more economical and convenient color stripping method.The results of FT-IR spectra,X-ray diffraction,gloss meter,SEM and KES fabric style meter show that the microstructure of the fiber macromolecular chains,aggregate structure and surface morphology have not changed significantly after stripping;while the fabric style which has no effect on the wearability of the fabric has changed to some extent.