电工技术学报2024，Vol.39Issue(1)：76-87,98,13.DOI:10.19595/j.cnki.1000-6753.tces.231446
黑曲霉菌对废旧电缆聚乙烯降解效果及反应机理研究
Degradation Effect and Degradation Mechanism of Aspergillus Niger on Polyethylene Components of Waste Cables
摘要
Abstract
In recent years,the accumulation of organic solid waste,particularly from the retirement of extensive cable systems,poses a significant threat to environmental cleanliness and human health.However,traditional incineration methods only exacerbate environmental pollution.Therefore,there is an urgent need for a safe and environmentally friendly degradation method to address the challenge of managing discarded cables.To investigate the process of microbial degradation of discarded polyethylene(PE)components,this study selected Aspergillus niger to treat polyethylene powder.The study examined the effects and reaction mechanisms of Aspergillus niger on the degradation of polyethylene in discarded cables by analyzing changes in functional groups,crystallinity,elemental composition,and the microscopic morphology of the samples. First,Fourier-transform infrared analysis(FTIR)was used to detect changes in the functional groups of the samples after treatment with Aspergillus niger.New functional groups,such as hydroxyl and carbonyl groups,were observed.Subsequently,the possible degradation products,such as alcohols and aldehydes,were analyzed through the newly formed chemical bonds.X-ray photoelectron spectroscopy(XPS)was employed to scan and analyze the changes in the carbon-oxygen elements on the sample's surface.After two weeks of treatment,the atomic ratio of oxygen elements on the surface increased from 1.38%to 13.6%.Further analysis of the sample's crystalline structure through X-ray diffraction(XRD)experiments revealed a decrease in crystallinity from 53.4%to 34.18%,indicating the disruption of the regularity of polymer molecular chains.In addition to these findings,a combined differential scanning calorimetry-thermogravimetric analysis(DSC-TGA)method was used to analyze the sample's thermal properties at different temperatures.The initial decomposition temperature decreased by 200℃,and the final decomposition temperature declined by 10℃.This phenomenon suggested the presence of lower-energy carbon-oxygen bonds during the degradation process,corresponding to the new functional groups observed in the FTIR analysis.Finally,scanning electron microscopy(SEM)was employed to observe the microscopic morphology of the samples at magnifications ranging from 10 000 to 50 000 times,revealing the presence of pores,grooves,cross-linking fractures,and other features on the sample's surface.This led to the inference that the samples had been attacked by extracellular enzymes produced by the Aspergillus niger. From the experimental results,the following conclusions can be drawn:(1)Aspergillus niger produces hydroxyl groups during the degradation of low-density polyethylene cable material.Subsequently,under the action of enzymes such as alcohol dehydrogenase and monooxygenase,these hydroxyl groups are converted into carbonyl and C—O—C groups,promoting the degradation process.(2)With increasing treatment time by Aspergillus niger,thermal decomposition and melting experiments indicate the presence of lower-energy carbon-oxygen bonds during the degradation process.This is consistent with the appearance of new functional groups in FTIR analysis and the increase in the atomic ratio of oxygen elements in XPS.(3)After being attacked by Aspergillus niger,the relative crystallinity of polyethylene samples decreased from 53.4%to 34.18%with prolonged treatment time.This phenomenon indicates that Aspergillus niger.can attack the polymer chains of polyethylene,disrupting their regularity and symmetry,leading to a reduction in crystallinity.(4)Microscopic observations of the sample's morphology revealed the presence of clear pores,grooves,and cross-linking fractures.This suggests that Aspergillus niger.can secrete extracellular enzymes to attack the polyethylene molecular chains,causing long-chain molecules to break into smaller chains and promoting degradation.关键词
废旧电缆/微生物/聚乙烯/生物降解Key words
Obsolete cables/microorganism/polyethylene/biodegradation分类
信息技术与安全科学引用本文复制引用
杨世芳,杨晓磊,谢军,侯前朋,刘云鹏..黑曲霉菌对废旧电缆聚乙烯降解效果及反应机理研究[J].电工技术学报,2024,39(1):76-87,98,13.基金项目
国家自然科学基金(52207154,52007065)、河北省自然科学基金(E2023502087)和中央高校基本科研业务费专项资金(2023MS104)资助项目. （52207154,52007065）
