摘要
为提高废弃纤维素纺织品的循环利用率,解决其引起的严重污染及浪费问题,介绍了水热降解法循环利用废弃纤维素纺织品的新途径。纤维素水热降解技术是一种利用亚(超)临界水进行热化学转化的新技术,综述了废弃纤维素纺织品水热降解技术的研究现状,分析了纤维素纤维亚(超)临界水热降解的机制、反应历程及产物种类,归纳了纤维素水热降解过程及降解产物的影响因素,对纤维素水热降解技术存在的问题及研究方向进行了总结与展望。分析认为:利用亚(超)临界水体系中水既是溶剂又是反应物和催化剂的特性,可以对纤维素类纺织品进行有效降解及分离回收,通过水解糖化、水热炭化等反应历程,得到水溶糖、水热炭、生物原油等多种水热产品;温度、时间、催化剂及纤维素结构对纤维素纤维水热降解有重要影响;目前该技术还存在部分反应机制不明确及目标产品产率较低等问题。基于这些问题对今后该领域的主要研究方向提出了建议。该技术绿色环保、成本低、产物可控、产品附加值高,具有很好的开发前景。
Significance Large amount of waste textiles are heaped up,landfilled or incinerated as solid waste year by year,leading to heavy pollution of the environment and waste of the resources.In the face of the worsening energy crisis and environment troubles,the recycling of waste textiles has become a pressing social problem to be tackled.Various ways have been used physically or chemically in the study of the recycling of waste textiles.Among others,hydrothermal degradation is a highly noticeable thermochemical conversion technology featuring environmental friendliness,productive richness,and economy,which can effectively degrade and recycle cellulose textiles,and obtain high value-added hydrothermal products.The green and high-valued recycling of waste textiles are of great economic and social importance for the development of circular economy and reduction of pollution and carbon emission.Progress New technologies are introduced for hydrothermal degradation of waste cellulose textiles in subcritical(supercritical)environments.With the special properties of subcritical(supercritical)water,cellulose fibers can be degraded hydrothermally into high value-added chemical products such as water-soluble sugar,hydrothermal carbon,and bio-oil.After step-by-step separation,the hydrothermal products can be effectively recovered without pollutant emission.The strong hydrogen bond and stable structure of high crystallinity of cellulose makes it hard to degrade at room temperature,which is the biggest problem in natural cellulose utilization.This paper analyzed the mechanism and reaction process of cellulose fiber hydrothermal degradation,summarized different processes of the hydrothermal degradation and corresponding target products,and concluded the influencing factors of the process and products.In the subcritical(supercritical)water system,acting as a reactant,a catalyst and an organic solvent concurrently,water can effectively break the hydrogen bond and crystal structure,and promote the break of glycosidic bond of cellulose.Under certain hydrothermal conditions,cellulose materials are degraded into substances such as glucose,fructose,5-HMF(5-hydroxymethylfurfural),and organic acids.The soluble oligomers obtained through hydrolysis will form various carbon containing materials,bio-oils,and a small amount of gases after dehydration,polymerization,condensation,and aromatization.The hydrothermal degradation can be divided into processes of hydrolytic saccharification,hydrothermal carbonization,hydrothermal liquefaction and hydrothermal gasification,with respective products of water-soluble sugar,hydrothermal carbon,bio-oil and gas products.Temperature,time,catalyst,and cellulose structure are important factors affecting the hydrothermal degradation process and degradation products of cellulose.Different reaction conditions result in different degradation rates,products,yields,and properties of the hydrothermal degradation.By adjusting the temperature,catalyst and other parameters,the hydrolysis process can be regulated and the selectivity of target products can be adjusted to achieve different target products.Conclusion and Prospect Hydrothermal treatment of cellulose fibers can yield high value-added chemical products such as glucose,5-HMF,lactic acid,and carbon microspheres,while selective degradation of cellulose fibers can achieve effective separation and recycling of cellulose based blended fabrics,demonstrating that hydrothermal degradation technology of cellulose fibers is an effective way for high-valued recycling of waste textiles.However,researches in the area are still in the phase of laboratory exploration,at certain distance from large-scale production,due to the complex process relating to cellulose hydrothermal degradation.Still,the complexity of the hydrothermal degradation process and uncertainty of the decomposition mechanism and pathway of intermediate products,and the catalytic mechanism and regulatory mechanism of catalysts led to low yield of target products.Consequently,additional research should be conducted on the existing issues.With the evolution of the research,the industrial application of hydrothermal degradation technology in waste textiles treatment in the future will achieve significant social and economic benefits.
作者
张永芳
费鹏飞
阎智锋
王淑花
郭红
ZHANG Yongfang;FEI Pengfei;YAN Zhifeng;WANG Shuhua;GUO Hong(College of Textile Engineering,Taiyuan University of Technology,Taiyuan,Shanxi 030024,China)
出处
《纺织学报》
EI
CAS
CSCD
北大核心
2023年第12期216-224,共9页
Journal of Textile Research
基金
国家自然科学基金项目(21802101)
山西省自然科学基金项目(20210302124492)。
关键词
废弃纤维素纺织品
循环再利用
水热降解
降解机制
亚(超)临界水热体系
waste cellulose textile
recycling
hydrothermal degradation
degradation mechanism
subcritical(supercritical)hydrothermal system
