Subcritical and supercritical water for chemical recycling of plastic waste

The use of plastic in daily life is growing at expressive rates. Because of its inherent characteristics, such as chemical resistance and low biodegradability, plastic waste is already a global issue. Traditionally used methods for plastic conversion, such as incineration, cause some environmental concerns, besides not being economically attractive. Subcritical and supercritical water provide a strongly oxidant environment, which can deal with this waste by allowing the obtention of high added-value products from waste of synthetic polymers. These processes, when carefully optimized using chemometric methods, produce fuels, and even the initial monomers that can be used for polymer synthesis, reducing the direct demand for fossil raw materials in a circular economy approach. [Display omitted] •Growing research efforts in supercritical water process lead to deep process knowledge.•Reaction kinetics should be considered to reach a specific product.•Process optimization beyond univariate experiments might allow better efficiencies.•Supercritical water processes are potential tools for recycling and reuse of polymer wastes.