Carbon Nanotubes Derived from Plastic Waste- a New Wave of Materials for Circular Economy

Abstract

Large amounts of plastic waste are generated worldwide. Owing to the lack of profitable solutions, the recycling rates for waste plastics are low. A new approach is required to convert mixed plastics into valuable products with potential monetary benefits to encourage waste collection and recovery, thus increasing circular economy concepts in waste management. This study focuses on the development of carbon based materials, such as carbon nanotubes (CNTs) from plastic waste (Fig. 1) containing high (H-PET) and low PET (L-PET) content and their subsequent application as materials for electrodes and the use in various analytical and process engineering systems. The plastic-derived CNTs were evaluated as electrocatalysts for hydrogen evolution (HER) and oxygen reduction reaction (ORR). The results from HER and ORR study were found comparable or better to the ones using commercial CNTs. The plastic waste derived CNTs were also evaluated as electrodes in various analytical applications, e.g. support and solid contact for ion-selective electrodes in potentiometry and detection of analytes with increased sensitivity in voltammetry. The results were compared to commercially available electrodes and materials derived from pure feedstock. Life cycle assessment (LCA) was conducted in order to identify the environmental impact and benefits of using waste over pure feedstock derived carbon materials in analytical applications. The results indicate that waste derived material perform equally well in analytical applications as the ones derived from pure feedstock. Furthermore, LCA indicates that the use of waste derived materials result in much lower environmental impacts compared to the pure feedstock derived carbon materials. This study strongly encourages the use of waste derived carbon materials in order to increase the circular economy concepts and decrease environmental impacts connected to material development and the use of materials in various applications. Fig. 1. Plastic waste derived CNTs. Figure 1