Study On Decolorization And Recovery Technology Of Waste Polyester / Cotton Fabric

The waste cotton fabrics were decolorized by reduction-oxidation method using sodium hydrosulfite-hydrogen decoloration system. The influence of decolorant concentration, sodium hydroxide concentration, decoloration time, pick up on decoloration rate and whiteness were discussed. The optimum decoloration process was as follows: sodium hydrosulfite 20g/L, sodium hydroxide 20g/L, pick up 100%(one impregnating and one padding), decoloration time 30 min, treated in 15g/L hydrogen peroxide for 30 min. Under this condition, the decoloration rate reached 97% with good whiteness and low strength loss, suitable for most of the decoloration process of cotton fabric dyed with reactive dyes.The common decolorants were selected to form a composite system DMSO/DMAc, decolorization of waste polyester-cotton fabric was decolorized. The influence of DMSO/ DMAc ratio, temperature, time, material ratio, pick up on decoloration rate, strength loss and water absorption were researched. The optimum decoloration condition was as follows: DMSO/DMAc ratio was 5:5, treating at 140℃ for 15 min, material ratio was 1:15. Under this condition, the decoloration rate reached 65% with good whiteness and low strength loss, suitable for most of the decoloration process of polyester-cotton fabric. Furthermore, the process is simple to use, economical, environment-friendly, and at low cost, well suited for industrial production.Pretreatment of waste polyester cotton fabrics were treated by alcoholysis with ethylene glycol separation test. The EG dosage, reaction time, reaction temperature, catalyst type on the influence of alcoholysis rate in the alcoholysis reaction was analysed to determine the optimum process of polyester/cotton alcoholysis reaction. The results show that, using zinc acetate as catalyst, mass ratio 1:7, reaction time was 60 min, the dosage of catalyst is0.03%, the alcoholysis rate was high, the product is white needle crystal.The alcoholysis products appraised by IR, DSC test, the alcoholysis products was determined as BHET. The isolated cotton group was taken the strength test, DSC, SEM test to determine the fiber damage degree, the degree was in the permissible range, little effect was in the subsequent use of the cotton fiber.