To Understand The Application Of Hydrothermal Recovery Of Waste Polyester Cotton Blended Fabric

In recent years, with the improvement of living standards, textile fiber consumption has increased rapidly. Tens of millions of tons of waste textiles produced every year are regarded as garbage burying or burning, which causes great ecological environment pressure and waste of resources.

However, the components of waste textiles are complex. According to the different uses of textiles, various dyes, pigments and auxiliaries added in the processing process bring certain difficulties to the recycling.

The waste polyester cotton blended fabric accounts for more than 50% of the waste textiles. Due to the particularity of the blended structure, the components of polyester and cotton can not be separated effectively.

At present, most of the waste blended fabrics are directly opened to form regenerated fibers by physical method without separation, and are prepared into low value-added products such as felt and fillers, which can not be recycled and reused with high added value.

Hydrothermal method, which takes water as reaction medium, is widely used in research because of its advantages of safety and environmental protection. In hydrothermal environment, subcritical water is ionized and ionic product constant is increased, which makes subcritical water have the characteristics of acid-base catalyst and organic solvent.

Under hydrothermal conditions, a small amount of acid catalyst can promote the rapid reaction, which makes the cotton fiber hydrolyze in the stable state of polyester, which makes the separation of waste polyester cotton blended fabric possible.

The recycling of waste polyester / cotton fabric and its recycling with water were studied. Firstly, cotton fiber and polyester fiber were taken as the research objects to study the hydrolysis mechanism of cotton fiber and the stability of polyester fiber under the catalysis of trace acid in subcritical water, and the degradation reaction law of cotton fiber in acidic subcritical water was clarified. Combined with the thermal stability of polyester fiber, the critical point of selective hydrolysis of polyester and cotton fiber in the same hydrothermal system was explored.

Then, the effects of hydrothermal temperature, reaction time and hydrochloric acid concentration on the selective hydrolysis of waste polyester / cotton blended fabric were studied with polyester recovery, cellulose powder yield and reducing sugar yield as indexes, and the physicochemical properties of the products after hydrothermal reaction were characterized

The results showed that the best separation effect was obtained under the conditions of hydrochloric acid concentration of 1%, hydrothermal temperature of 140 ℃ and reaction time of 2.5 h The recovered cotton fiber products are solid cellulose or oligosaccharides; There is no obvious loss in the physicochemical properties of polyester, and the recovery rate can reach more than 90%. The waste polyester cotton blended fabric after hydrothermal reaction has high added value and is widely used.