Plastics have become indispensable in modern society; however, the proliferation of their waste has become a problem that can no longer be ignored as most plastics are not biodegradable. Depolymerization/degradation through sustainable processes in the context of the circular economy are urgent issues. The presence of multiple types of plastic materials makes it necessary to study the specific characteristics of each material. This mini-review aims to provide an overview of technological approaches and their performance for the depolymerization and/or degradation of one of the most widespread plastic materials, polypropylene (PP). The state of the art is presented, describing the most relevant technologies focusing on advanced oxidation technologies (AOT) and the results obtained so far for some of the approaches, such as ozonation, sonochemistry, or photocatalysis, with the final aim of making more sustainable the PP depolymerization/degradation process.

The valorization of spent coffee ground wastes to prepare advanced materials offers a promising pathway toward sustainable materials engineering. In this work, spent coffee grounds were valorized by their utilization as a template for the synthesis of Ce‐loaded TiO ₂ to be used as photocatalysts. The synthesis in the presence of the bio‐derived sacrificial template in the absence of solvent promote a hierarchical porosity and surface area and an intimate contact between Ce and Ti precursors to improve the photocatalytic activity of the obtained composite material. Pure TiO ₂ is made up of nanoparticles that organize into fairly uniform spherical agglomerates of ca. 1 μm. When Ce is introduced, this ordered structure gradually changes giving rise to less regular larger aggregates, and at higher loadings (5% Ce) the spherical morphology is no longer observed. In all cases a mesoporous structure is present. The activity of the obtained solids as photocatalysts was tested in three different reactions: (i) the photo reforming of ethanol in aqueous suspension of the photocatalysts in the absence of oxygen, to obtain hydrogen; (ii) the 2‐propanol oxidation in gas–solid regime, and (iii) the 5‑hydroxymethylfurfural (5‑HMF) oxidation in aqueous suspension of the solids.