A review of the co-liquefaction of biomass feedstocks and plastic wastes for biofuel production

Interest has emerged recently in addressing the long-standing issue of waste plastic disposal and environmental challenges through the co-liquefaction of waste plastics with eco-friendly renewable biomass resources, including microalgae biomass and lignocellulosic biomass, to produce biofuels. Co-liquefaction provides a viable alternative for managing plastic waste while contributing to biofuel production. The purpose of this article is to provide a comprehensive review of the advances in the co-liquefaction of various mixtures of plastic waste and different types of biomass feedstocks (lignocellulosic and algal) for the production of biofuels.The influence of various reaction parameters, such as feedstock composition (blending ratio), temperature, catalyst type and loading, solvents, and reaction time on the product yield are explored. The synergistic interaction during the co-liquefaction of biomass and plastic and the distribution and properties of biofuel products are also discussed.The findings demonstrate that maximum product yields vary depending on the final temperature, and the blending ratio plays a crucial role in determining the distribution of liquefaction products. Of particular interest is biocrude oil, the components of which are influenced by the composition of the feedstock material. The distribution of organic elements in the biochar is contingent upon the type of plastic used. Although the analysis of gas-phase components is often overlooked, the reaction medium's composition is shown to impact the resulting gas composition.Finally, based on the insights gleaned from the literature, this review presents future perspectives on the subject matter. In general, the co-liquefaction process offers a viable option for sustainable biofuel production and is a promising approach to address the waste plastics disposal challenges effectively, contributing to the valorization of plastic waste to achieve a circular bioeconomy in the future.