Baolong Wang,Xinyu Wang,Ningdi Xu,Yibo Shen,Fei Lu,Yingying Liu,Yudong Huang,Zhen Hu
Unsaturated polyester resins (UPRs) composites have many industrial applications, such as fan blades in wind energy. However, the stable cross-linked polymer networks of resin matrix lead to large numbers of composite wastes that are difficult to recycle. Developing an efficient approach to explore the recovery of high-value fiber from composites is thus imperative. In this paper, an efficient and mild hydrolysis-oxidation synergistic catalytic strategy was proposed to efficiently recycle carbon fibers from UPRs composites by selectively cleaving chemical bonds of UPRs. Ester bonds in UPRs were cleaved by using hydrolysis of 80% hydrazine hydrate along with NaOH. Afterwards, the cleavage of carbon-carbon bonds was accomplished via the Fenton reaction for the purpose of complete degrading UPRs. The result figured that UPRs could be efficiently degraded at 100 °C below via this hydrolysis-oxidation strategy. Interestingly, applying the strategy, the recovery of carbon fibers from UPRs composites was investigated. The reclaimed carbon fibers kept their original surface microscopic morphology , chemical structure and tensile strength almost close to the virgin carbon fibers. This strategy opens up a new way for efficient and mild degradation of thermosets .
Tao Zhang,Shuang-yan Xu,Hui Lin,Jian Yang,Zhuo-qun Zhao,Damià Barceló,Hua-bao Zheng
Tylosin is widely used in livestock; however, the release of tylosin through animal manure can cause serious environmental problems. In this study, a new tylosin-degrading strain, TYL-T1, was isolated. Its phylogenetic similarity to Klebsiella oxytoca was found to be 99.17 %. TYL-T1 maintained good growth at 40 °C over a broad pH range (4.0–10). TYL-T1 degraded 99.34 % of tylosin in 36 h under optimal conditions (tylosin initial concentration: 25 mg/L, pH: 7.0, and temperature: 35 °C). After LC-MS-MS analysis, a new degradation pathway for tylosin was proposed, including ester bond breaking of the macrolide lactone ring, redox reaction, and loss of mycinose and mycarose. Based on a transcriptome analysis, 164 genes essential for degradation were upregulated through hydrolysis and redox of tylosin. Among various transferases, lipopolysaccharide methyltransferase, glycogen glucosyltransferase, and fructotransferase were responsible for tylosin degradation. The present study revealed the degradation mechanism of tylosin and highlighted the potential of Klebsiella oxytoca TYL-T1 to remove tylosin from the environment.
危险品化学品经营许可证（带存储）