Oxygen-mediated acceleration of chloride capture and migration by copper oxide in PVC-based cable pyrolysis

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.