Upcycling polyvinyl chloride (PVC) using iron oxide for fabrication of carbon encapsulated iron (Fe@C) sub-micron particles and FeCl 2

Abstract Clean and value-added upcycling of waste PVC, normally comprising de-chlorination and end-treatment, is highly desired for a sustainable society. Magnetite, Fe 3 O 4 , has been proven an efficient PVC de-chlorination agent, resulting in FeCl 2 , polyene and Fe 2 O 3 . Obviously, the interaction between Fe 2 O 3 and PVC is inevitable. The current study investigated the reaction mechanism between Fe 2 O 3 and PVC in comparison with Fe 3 O 4 to improve the chlorine fixing ratio in FeCl 2 , and manufacture magnetic carbon encapsulated iron (Fe@C) particles, accomplishing a full upcycling of waste PVC. Fe 2 O 3 fixes less chlorine in FeCl 2 than Fe 3 O 4 because the reduction of Fe 3+ to Fe 2+ plays a key role on FeCl 2 formation. The diffusion of gaseous reactants, H 2 and HCl, through a boundary layer to the surface of Fe 2 O 3 particles is the controlling step. Prolonging the residence time of internally generated H 2 and HCl by increasing the sample packing thickness is an effective way to improve the chlorine fixing ratio in FeCl 2 . For PVC + 75 %Fe 2 O 3 mixture, chlorine fixing ratio in FeCl 2 can be promoted to 0.95 from 0.78 when the sample thickness was increased to 2.5 cm from 0.5 cm. After water-leaching FeCl 2 , the sediment was heated to above 1,273 K and nano-size metallic iron particles covered with carbon, Fe@C, were obtained. The Fe@C particles exhibit excellent magnetic property combination of a high saturation magnetization (160 kA/m) and a small coercivity (14 kA/m).