Carbon residue from co-pyrolysis of cartons and plastics: Characteristics, environmental behaviors and applications

The continuously growing of municipal solid waste (MSW) has posed a threat to human-being. Pyrolysis is a promising technique for MSW disposal, as it can reduce its volume and produce valuable products as well. This study evaluated the potential of carbon residue (CR) derived from waste carton as soil amendment. Additionally, considering the waste plastics, such as plastic bags, plastic tape, etc., can mix with carton in MSW, the effect of polyvinyl chloride (PVC) addition on the characteristics of CR and its environmental behavior was measured. Results showed that the CR derived from carton exhibited notable efficacy in adsorbing Cd2+ (56.111 mg/g), pesticides and PO43- (0.231 mmol/g), thereby mitigating pollutants and immobilizing nutrient in soil environment. The introduction of PVC was found to enhance the adsorption of CR for Cd2+ (65.623 mg/g) and PO4 3- (0.524 mmol/g), albeit exhibiting diminished performance in the removal of pesticides. Different from previous studies, this study revealed that the dissolved black carbon (DBC) released from CRs did not generate reactive oxygen species (ROS) effectively under solar irradiation, and the light screening of DBC can mitigate the photodegradation of pollutants. Furthermore, both CRs increased bacterial luminescence by approximately 70%, which indicated that no toxicity produced during the pyrolysis process. And gas chromatography-mass spectrometry (GC-MS) revealed the absence of polyaromatic hydrocarbon (PAH) in CRs. In summary, this study may provide some new insights on the disposal of MSW, and the CR made by MSW could be effective in soil amendment and reduce the leaching of pollutants and nutrient.