Study On Clean And Efficient Separation Of Waste Polyester Cotton Blended Fabric And Reuse Of Cotton Based Cellulose

The recycling of waste textiles is of great significance to save resources,reduce pollution and carbon.It is an important measure to effectively supplement the supply of raw materials in China’s textile industry and alleviate the constraints of resources and environment.It is also an important content of establishing and perfecting the green and low-carbon circular development economic system.Therefore,based on the recycling of polyester cotton blended fabric with the largest output,this paper explored a clean and efficient separation method,realized the high-value utilization of cotton based cellulose and polyester respectively through the untwisting and separation of blended fabric,and constructed a complete recycling system of waste polyester cotton fabric.The main research work is as follows:(1)In view of the problem that the structure of polyester and cotton fiber blended yarn in the fabric is tightly wound,which is difficult to separate and cannot be processed,the cotton fiber in the blended fabric was selectively hydrolyzed by hydrothermal system with low concentration natural organic acid(acetic acid,oxalic acid,malic acid and citric acid)as catalyst,so as to release polyester fiber and realize effective separation.It was determined that oxalic acid had excellent separation effect.The results show that compared with inorganic acid,oxalic acid can achieve the same separation effect as strong acid under the same reaction conditions,and the morphology of polyester fiber is more complete,the hydrolysis degree of cotton fiber is lower,and the distribution of hydrolysate is narrower;When the concentration of oxalic acid is 0.07 mol/L,the reaction temperature is 130℃ and the reaction time is 3 h,the separation effect of blended fabric is the best.The cotton fiber is hydrolyzed into cellulose material with a yield of 91.46%,and a small part is hydrolyzed into glucose or oligosaccharide;the recovery rate of polyester fiber is up to 99.28%,and retains the properties of the original polyester fiber,which can be directly produced and processed;the reaction system can be recycled for many times to realize the efficient utilization of waste polyester cotton blended fabric.(2)In order to further improve the separation efficiency of the fabric and reduce the reaction conditions,the low eutectic solvent p-toluenesulfonic acid/choline chloride(T-DES),which is conducive to the dissolution of cotton fiber,was synthesized by heating and stirring with p-toluenesulfonic acid as the hydrogen bond donor and choline chloride as the hydrogen bond receptor.The mixed solvent was formed with water to construct the reaction system.The effects of T-DES water content,reaction temperature and time on fabric separation were explored.The separated polyester fiber and cellulose were characterized and analyzed,and the recycling of the system was studied.The results show that when the water content of T-DES is 25%,the reaction temperature is 90℃,and the reaction time is 40 min,the polyester cotton component has the best separation effect.At this time,the recovery of polyester is98.48%,and the yield of cellulose can reach 87.57%.Compared with oxalic acid hydrothermal system,on the premise of equivalent separation effect,the reaction efficiency is greatly improved,the reaction temperature is significantly reduced,and T-DES can be reused for 5 times after recovery.(3)In order to realize the closed-loop recycling of waste textiles and improve the high-value utilization of recycled products,the separated cotton based cellulose was mixed with polymers,and the reused fiber membrane was prepared by electrospinning technology.The effects of spinning process and blending ratio on the morphology of fiber membrane were studied,and the prepared fiber membrane was characterized and analyzed.The results show that under the appropriate process conditions(spinning voltage 17 k V,injection speed 0.25mm/min,receiving distance 10 cm),the fiber membrane with good shape and smooth surface can be prepared.When the blend ratio of cellulose/polyacrylonitrile is 30/70,the blend fiber membrane has good thermal stability and hydrophilicity.