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.
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.
Yang Shifang, Yang Xiaolei, Xie Jun, Hou Qianpeng, Liu Yunpeng. Degradation Effect and Degradation Mechanism of Aspergillus Niger on Polyethylene Components of Waste Cables. Transactions of China Electrotechnical Society, 2024, 39(1): 76-87.
[1] 王镜然, 王英杰, 庄宏伟, 等. 低压电缆绝缘热氧老化过程中介电响应的Davidson-Cole分析[J]. 电工技术学报, 2023, 38(15): 4030-4039. Wang Jingran, Wang Yingjie, Zhuang Hongwei, et al.Dielectric response during thermal-oxidative aging of low-voltage cable insulation analyzed by davidson-cole[J]. Transactions of China Electrotechnical Society, 2023, 38(15): 4030-4039. [2] 王湄, 黄斯平, 林远, 等. 浅析绿色环保概念在电线电缆中的应用[J]. 质量探索, 2022, 19(2): 91-94. Wang Mei, Huang Siping, Lin Yuan, et al.Application of green environmental concept in wires and cables[J]. Quality Exploration, 2022, 19(2): 91-94. [3] 王昊月, 李成榕, 王伟, 等. 高压频域介电谱诊断XLPE电缆局部绝缘老化缺陷的研究[J]. 电工技术学报, 2022, 37(6): 1542-1553. Wang Haoyue, Li Chengrong, Wang Wei, et al.Local aging diagnosis of XLPE cables using high voltage frequency domain dielectric spectroscopy[J]. Transactions of China Electrotechnical Society, 2022, 37(6): 1542-1553. [4] 陈向荣, 洪泽林, 朱光宇, 等. 高温下电压稳定剂对交联聚乙烯电树枝化及局部放电特性的影响[J]. 电工技术学报, 2023, 38(3): 577-586. Chen Xiangrong, Hong Zelin, Zhu Guangyu, et al.Effect of voltage stabilizer on electrical treeing and partial discharge characteristics of crosslinked polyethylene at high temperature[J]. Transactions of China Electrotechnical Society, 2023, 38(3): 577-586. [5] 王国栋, 周凯, 李原, 等. 基于失效时间统计特性的交联聚乙烯电寿命模型修正[J]. 电工技术学报, 2023, 38(4): 1042-1050. Wang Guodong, Zhou Kai, Li Yuan, et al.Modification of cross-linked polyethylene electrical life model based on statistical characteristics of failure time[J]. Transactions of China Electrotechnical Society, 2023, 38(4): 1042-1050. [6] 王昊月, 王晓威, 孙茂伦, 等. XLPE电缆绝缘热老化的高压频域介电谱诊断方法[J]. 电工技术学报, 2022, 37(17): 4497-4507. Wang Haoyue, Wang Xiaowei, Sun Maolun, et al.High voltage frequency domain dielectric spectro-scopy diagnosis method for thermal aging of XPLE cables[J]. Transactions of China Electrotechnical Society, 2022, 37(17): 4497-4507. [7] 刘文杰, 陈杰, 江平开, 等. 环境友好热固性电工绝缘材料与制备技术[J]. 电工技术学报, 2022, 37(5): 1115-1127. Liu Wenjie, Chen Jie, Jiang Pingkai, et al.Environmental-friendly electrical insulating thermosets and preparation technology[J]. Transactions of China Electrotechnical Society, 2022, 37(5): 1115-1127. [8] Balasubramanian V, Natarajan K, Hemambika B, et al.High-density polyethylene (HDPE)-degrading potential bacteria from marine ecosystem of Gulf of Mannar, India[J]. Letters in Applied Microbiology, 2010, 51(2): 205-211. [9] Harshvardhan K, Jha B.Biodegradation of low-density polyethylene by marine bacteria from pelagic waters, Arabian Sea, India[J]. Marine Pollution Bulletin, 2013, 77(1/2): 100-106. [10] Tribedi P, Sil A K.Low-density polyethylene degradation by pseudomonas sp. AKS2 biofilm[J]. Environmental Science and Pollution Research, 2013, 20(6): 4146-4153. [11] 冯静. 白浅灰链霉菌对聚乙烯降解效果研究及降解酶的基因克隆[D]. 成都: 四川师范大学, 2016. [12] Li Zhongyu, Wei Ren, Gao Meixi, et al.Biodegradation of low-density polyethylene by Microbulbifer hydrolyticus IRE-31[J]. Journal of Environmental Management, 2020, 263: 110402. [13] 李玮, 王丹丹, 庞诗琪, 等. 大麦虫及其肠道微生物对聚乙烯的生物降解[J]. 微生物学通报, 2023, 50(4): 1422-1431. Li Wei, Wang Dandan, Pang Shiqi, et al.Biodegradation of polyethylene by zophobas atratus and its gut microorganisms[J]. Microbiology China, 2023, 50(4): 1422-1431. [14] 吴慧. 生物降解高密度聚乙烯基农用覆盖地膜及降解机理研究[D]. 兰州: 西北民族大学, 2023. [15] El-Sayed M T, Rabie G H, Hamed E A. Biodegradation of low-density polyethylene (LDPE) using the mixed culture of Aspergillus carbonarius and A. fumigates[J]. Environment, Development and Sustainability, 2021, 23(10): 14556-14584. [16] Khandare S D, Agrawal D, Mehru N, et al.Marine bacterial based enzymatic degradation of low-density polyethylene (LDPE) plastic[J]. Journal of Environmental Chemical Engineering, 2022, 10(3): 107437. [17] Tiwari N, Santhiya D, Sharma J G.Degradation of polyethylene microplastics through microbial action by a soil isolate of BreviBacillus brevis[J]. Polymer Degradation and Stability, 2023, 215: 110436. [18] Canevarolo S V.Chain scission distribution function for polypropylene degradation during multiple extrusions[J]. Polymer Degradation and Stability, 2000, 70(1): 71-76. [19] Ojha N, Pradhan N, Singh S, et al.Evaluation of HDPE and LDPE degradation by fungus, implemented by statistical optimization[J]. Scientific Reports, 2017, 7: 39515. [20] Ji Y, Mao G, Wang Y, et al.Structural insights into diversity and n-alkane biodegradation mechanisms of alkane hydroxylases[J]. Frontiers in microbiology, 2013, 4: 58. [21] Yeom S J, Le T K, Yun C H.P450-driven plastic-degrading synthetic bacteria[J]. Trends in Bio-technology, 2022, 40(2): 166-179. [22] Hou Lijun, Xi Jiao, Liu Jiaxi, et al.Biodegradability of polyethylene mulching film by two Pseudomonas bacteria and their potential degradation mechanism[J]. Chemosphere, 2022, 286: 131758. [23] 唐俊, 赵文强, 侍乔明, 等. 混合级联特高压直流系统解/闭锁问题分析及对策[J]. 电力系统自动化, 2023, 47(16): 171-180. Tang Jun, Zhao Wenqiang, Shi Qiaoming, et al.Analysis and countermeasures of deblocking/blocking problems in hybrid cascaded UHVDC system[J]. Automation of Electric Power Systems, 2023, 47(16): 171-180. [24] 李忠磊, 赵宇彤, 韩涛, 等. 高压电缆半导电屏蔽材料研究进展与展望[J]. 电工技术学报, 2022, 37(9): 2341-2354. Li Zhonglei, Zhao Yutong, Han Tao, et al.Research progress and prospect of semi-conductive shielding composites for high-voltage cables[J]. Transactions of China Electrotechnical Society, 2022, 37(9): 2341-2354. [25] 王昱力, 黄凯文, 王格, 等. 基于Comsol仿真的高压直流电缆附件材料电导率特性研究[J]. 高压电器, 2023, 59(9): 258-267. Wang Yuli, Huang Kaiwen, Wang Ge, et al.Research on conductivity characteristics of HVDC cable accessory material based on comsol simulation[J]. High Voltage Apparatus, 2023, 59(9): 258-267. [26] Kawai F, Watanabe M, Shibata M, et al.Comparative study on biodegradability of polyethylene wax by bacteria and fungi[J]. Polymer Degradation and Stability, 2004, 86(1): 105-114. [27] Gao Rongrong, Liu Rui, Sun Chaomin.A marine fungus Alternaria alternata FB1 efficiently degrades polyethylene[J]. Journal of Hazardous Materials, 2022, 431: 128617. [28] Sarathi R, Das S, Anil Kumar C R, et al. Analysis of failure of crosslinked polyethylene cables because of electrical treeing: a physicochemical approach[J]. Journal of Applied Polymer Science, 2004, 92(4): 2169-2178. [29] Gulmine J V, Akcelrud L.Correlations between the processing variables and morphology of crosslinked polyethylene[J]. Journal of Applied Polymer Science, 2004, 94(1): 222-230. [30] Ratner S, Weinberg A, Marom G.Morphology and mechanical properties of crosslinked PE/PE composite materials[J]. Polymer Composites, 2003, 24(3): 422-427. [31] Rummel C D, Jahnke A, Gorokhova E, et al.Impacts of biofilm formation on the fate and potential effects of microplastic in the aquatic environment[J]. Environmental Science & Technology Letters, 2017, 4(7): 258-267. [32] Kasirajan S, Ngouajio M.Polyethylene and biodegradable mulches for agricultural applications: a review[J]. Agronomy for Sustainable Development, 2012, 32(2): 501-529. [33] Ivshina I B, Kuyukina M S, Krivoruchko A V, et al.Responses to ecopollutants and pathogenization risks of saprotrophic rhodococcus species[J]. Pathogens, 2021, 10(8): 974. [34] Jeon H J, Kim M N.Functional analysis of alkane hydroxylase system derived from Pseudomonas aeruginosa E7 for low molecular weight polyethylene biodegradation[J]. International Biodeterioration & Biodegradation, 2015, 103: 141-146. [35] Restrepo-Flórez J M, Bassi A, Thompson M R. Microbial degradation and deterioration of polyethylene-a review[J]. International Biodeterioration & Biodegradation, 2014, 88: 83-90. [36] Ali S S, Elsamahy T, Al-Tohamy R, et al.Plastic wastes biodegradation: mechanisms, challenges and future prospects[J]. Science of the Total Environment, 2021, 780: 146590. [37] Ali Shah A, Hasan F, Hameed A, et al.Biological degradation of plastics: a comprehensive review[J]. Biotechnology Advances, 2008, 26(3): 246-265. [38] Van Beilen J B, Li Z, Duetz W A, et al. Diversity of alkane hydroxylase systems in the environment[J]. Oil & Gas Science and Technology, 2003, 58(4): 427-440.
2024, Vol. 39 
