Zou Yanyan,Li Yaoqiang,Zhang Jiaqing,Guo Yi,Song Tonglei,Li Kaiyuan,Xu Mingjun
The incineration of a large number of old cables leads to the problem of green recycling and causes a lot of environmental problems. This paper investigates the effect of copper oxide (CuO) capture of chlorine (Cl) in the pyrolysis recycling of polyvinyl chloride (PVC)-based waste cable outer sheath, focusing on the redistribution of the contaminant Cl components under the action of oxygen (O 2 ). Analytical methods such as ion chromatography and diffraction of X-rays are employed to measure and quantify the dynamic changes of the Cl-containing three-phase products during the pyrolysis process. The results indicate that, compared to copper (Cu), the oxidized state of CuO and O 2 -rich conditions can enhance the capture of Cl. With increasing O 2 supply, 1.71–6.33 mass% of gas-phase Cl and 14.52–29.96 mass% of liquid-phase Cl convert into 16.23–36.29 mass% of solid-phase Cl. CuO reacts directly with the PVC component of the outer sheath in a solid–solid reaction, significantly reducing the generation of polluting Cl-containing aromatic compounds in the liquid-phase tar and synergistically facilitating CaCO 3 components to intimately contact with the pyrolysis gas to capture HCl. The originally stable CuCl 2 crystals are oxidized again to enter into cyclic adsorption in the form of CuO under O 2 -rich conditions. Cl is more fixed in the residue and primarily exists in the form of stable and safe CuCl 2 and CaCl 2 metallic compounds. This study has clearly elucidated the efficient in situ green solidification mechanism of Cl during the treatment of cable waste with CuO in the presence of O 2 , providing new recommendations for cable sheath formulations and solid waste management.
The molecules O2 and H2O dominate the cleavage of aromatic sp2 C–C bonds, a crucial step in the degradation of aromatic pollutants in aqueous TiO2 photocatalysis, but their precise roles in this process have remained elusive. This can be attributed to the complex oxidative species involved and to a lack of available models for reactions with a high yield of direct products. Here, we used oxygen-18 isotope labeled O2 and H2O to observe the aromatic ring-opening reaction of the model compound 3,5-di-tert-butylcatechol (DTBC), which was mediated by TiO2 photocatalysis in an aqueous acetonitrile solution. By analyzing the primary intermediate products (∼75% yield), especially the seven-membered ring anhydrides that were formed, we obtained direct evidence for the oxygen atom of dioxygen insertion into a C–C bond of the aromatic ring. This indicates that molecular oxygen is the ultimate ring-opening agent in TiO2 photocatalysis and that it undergoes single O atom incorporation rather than the previously proposed molecular oxygen 1,2-addition processes. The ratio of intradiol to extradiol products depends on the particle size of TiO2 catalysts used, which suggests that the O2 activation is correlated with the available coordination sites on the TiO2 surface in the photocatalytic cleavage of the aromatic ring.
危险品化学品经营许可证（带存储）