Study On The Synergistic Pyrolysis Characteristics Of Polyester Cotton Textiles And The Adsorption Mechanism Of Cr(Ⅵ) By Solid Phase Product Carbon

The existing waste textiles are produced in large quantities,difficult to handle and difficult to recycle.Among the various technologies,the pyrolysis is a clean and efficient thermal conversion method for converting them into low-molecular substances.Co-pyrolysis is an important way to achieve efficient and sustainable utilization of pure cotton and polyester.The interaction between cotton and polyester during co-pyrolysis leads to a very complex co-pyrolysis reaction process.To address this problem,this study investigated the characteristics and interactions between cotton and polyester co-pyrolysis from cotton and polyester co-pyrolysis;and modified and prepared low-cost and environment-friendly biochar materials using zinc chloride and used them for the removal of Cr（Ⅵ）pollution in water.The main research of this paper is as follows:（1）This research investigates the mechanism of co-pyrolysis in waste-blended textiles（polyester/cotton blends）.The elements composition,approximate analysis and calorific value are discussed.Thermogravimetry and mass spectrometry analysis were utilized to study the mass loss behavior and gas emission characteristics of cellulose（CE）and polyethylene terephthalate（PET）with various mass ratios during pyrolysis.The EA,BET and FTIR analysis were used to investigate the interaction among the solid phase products.The findings revealed a clear synergistic effect between CE and PET.When the theoretical and actual thermogravimetry/gas release curves were compared,the synergistic effect in the co-pyrolysis process inhibited a release of small volatile substances（H₂,CH₄,C₂H₂,CO and CO₂）at high temperatures and directly promoted hydrocarbon enrichment in solid products,which could affect the adsorption performance of solid phase products,and the inhibition effect was strongest when the ratio was 35:65.（2）This study confirms the synergistic effect in the pyrolysis process of polyester cotton blended textiles.Using polyester cotton blended textiles as raw materials and zinc chloride as an activator,biochar was prepared through one-step pyrolysis at 500℃,and Cr（Ⅵ）was removed from aqueous solution.The experimental results indicate that zinc chloride promotes the pyrolysis and pore structure formation of waste textiles at lower temperatures during the synthesis of zinc chloride modified biochar（BC-Zn Cl₂）,and BC-Zn Cl₂ has a clear microporous structure.In addition,the adsorption experiments have shown that the removal of Cr（Ⅵ）by BC-Zn Cl₂ is a multi-stage process dominated by chemical adsorption.Coexistent ion and cycling experiments have confirmed that BC-Zn Cl₂ has strong anti-interference performance and stability.FTIR and XPS characterization confirmed the involvement of oxygen-containing groups in the removal of Cr（Ⅵ）.The adsorption mechanism includes electrostatic action,reduction action and complexation.The study shows that the polyester-cotton carbon had great application potential to remove Cr（Ⅵ）by using the synergy effect of cotton and polyester.The interaction of mixed waste textiles in the pyrolysis process is confirmed,which provides a new method and idea for the treatment of mixed waste textiles.