离子液体萃取分离废弃涤/棉混纺材料的基础研究

Polyester/cotton blend fibers are a kind of textile materials with huge consumption. There are a large number of waste textiles generated every year, which can't be recycled because of difficultly separation of polyester and cotton. In order to explore a solutions to separate the polyester/cotton blend fibers, and recycle polyester and cotton at the same time, in this project the ionic liquids will be used to extract the cellulose from polyester/cotton blends, to achieve efficiently separation of the polyester/cotton. In view of degration possibility of the polyester (PET) in the ionic liquids for prolonged treatment at high temperature, We will synthesis and pick up a series of imidazole ionic liquids with different anionic, which can only dissolute cellulose. The optimum conditions of extraction and separation of polyester/cotton are also explored. The relationship between polyester degradation behavior in ionic liquids and the factors will be studied, such as the substituent structure and anions, pH value of ionic liquids. We will aslo explore the reaction conditions, the process impact of the PET degradation,and the dynamic process of PET degradation. Combined with of composition and structure analysis of the degradation products, we try to reveal the interaction mechanism between the ionic liquids and PET in various types of fiber materials.On this basis, we will explore how to control the extraction conditions for inhibition of the polyester degradation in ionic liquids. The extraction, separation and regeneration process and conditions of Polyester / cotton blend material in the ionic liquid will be optimized. We try to establish a green, pollution-free and low-energy for recycling and reuse of polyester / cotton blended fabric. The project will provide a new way and good idea to reuse and recycle the waste textiles. Furthermore, it is of great significance to develop the circular economy, but also for environmental protection and sustainable development.

涤/棉混纺是消费量巨大的的纺织材料，每年都有大量废弃物产生，因难以将涤纶和棉分离，无法回收再利用。为了探索解决分离涤/棉混纺,同时回收涤纶和棉的问题，本项目提出采用绿色溶剂-离子液体萃取涤/棉混纺中的棉纤维素，实现涤/棉的高效分离,回收涤纶与再生纤维素。鉴于涤纶(PET)在离子液体中长时间高温处理存在的降解可能性，项目主要研究离子液体的阳离子结构、阴离子种类、酸碱性等因素与涤纶降解行为之间的相互关系，探索反应条件、工艺对PET降解的影响规律，研究PET降解的动力学过程，结合降解产物的组成与结构分析，揭示离子液体与混纺材料中的PET相互作用的机理。在此基础上，探索如何控制合适的萃取条件，抑制涤纶在离子液体中的降解性。研究涤/棉混纺材料在离子液体中的萃取、分离与再生规律，并优化其工艺条件，建立一条绿色、无污染低耗能回收再利用涤/棉的方法，实现混纺织物的资源化再利用。

纺织品回收利用是纺织行业十三五规划的重点发展方向，也是社会关注的热点问题之一。为了探索解决混纺材料回收分离的难题，项目提出以离子液体为溶剂萃取涤棉混纺中的棉纤维素，实现涤/棉的高效分离，回收涤纶（PET）与再生纤维素。围绕废旧纺织品的循环利用，以涤纶和涤棉混纺材料为主要对象，项目探索了废旧纺织材料的分离与萃取新技术，详细如下：（1）涤纶在离子液体中长时间高温处理会降解而非溶解，反应温度是降解的关键因素，降解亦受离子液体的阳离子结构、阴离子种类和酸碱性的影响，动力学分析表明PET降解为一阶动力学过程，缩芯模型模拟显示降解主要发生在PET的外表面，为化学反应控制，IR、DSC、SEM等说明降解产物仍为PET但分子量明显降低且含有少量的氮元素，推断涤纶在离子液体的降解为PET在离子液体阴阳离子共同作用下，因受热发生酯基-COO随机断裂。控制温度是抑制PET降解的关键。（2）开发涤/棉混纺材料在离子液体中的萃取与分离工艺，实现混纺织物的资源化再利用。以易得的氯系、醋酸根咪唑类离子液体为萃取剂（固液比1：50），严格控制萃取温度（≦120℃），涤棉混纺粉碎后反应1-6h，离心分离可得涤纶和再生纤维素溶液，经TG、DSC、SEM、IR证实回收PET与原PET无明显变化，可熔融再利用，或是采用乙二醇催化降解为BHET再予以回收，再生纤维素溶液加水再生回收可达99%。（3）围绕涤纶废物的降解回收，探索了碱性咪唑类离子液体、磁性固体碱Fe3O4/MO（M=Mg、Ca、Ni）、铁氧体MFe2O4（M=Zn、Mn、Ni）三类催化剂的制备与表征，并应用于催化乙二醇醇解PET，固体催化剂均具有较好的催化效果，并可通过磁场快速回收；醇解产物经熔点、红外、热重、差热、核磁共振氢谱、质谱等表征，证实其为对苯二甲酸乙二醇酯BHET。（4）针对有色涤纶的回收，开发了溶剂法涤纶快速剥色工艺，以二甲亚砜为溶胀剂120℃先进行溶胀，再用冰乙酸110℃快速剥色。项目尝试建立一条绿色、无污染、低耗能，同时回收再利用涤棉的方法，为纺织废弃物的循环利用提供了一种新的思路和途径。