Fast pyrolysis bio-oils are feasible energy carriers and a potential source of chemicals. Detailed characterization of bio-oils is essential to further develop its potential use. In this study, quantitative ¹³C nuclear magnetic resonance (¹³C NMR) combined with comprehensive two-dimensional gas chromatography (GC × GC) was used to characterize fast pyrolysis bio-oils originated from pinewood, wheat straw, and rapeseed cake. The combination of both techniques provided new information on the chemical composition of bio-oils for further upgrading. ¹³C NMR analysis indicated that pinewood-based bio-oil contained mostly methoxy/hydroxyl (≈30%) and carbohydrate (≈27%) carbons; wheat straw bio-oil showed to have high amount of alkyl (≈35%) and aromatic (≈30%) carbons, while rapeseed cake-based bio-oil had great portions of alkyl carbons (≈82%). More than 200 compounds were identified and quantified using GC × GC coupled to a flame ionization detector (FID) and a time of flight mass spectrometer (TOF-MS). Nonaromatics were the most abundant and comprised about 50% of the total mass of compounds identified and quantified via GC × GC. In addition, this analytical approach allowed the quantification of high value-added phenolic compounds, as well as of low molecular weight carboxylic acids and aldehydes, which exacerbate the unstable and corrosive character of the bio-oil.

Durability has become a valuable design aspect for designers, manufacturers, service providers, and end-of-life actors. Nowadays, developing products for new business models based on renting and servitization practices is of paramount importance. Furthermore, durability enables the application of circularity strategies for product lifespan extension, including reuse, repair, refurbish, and remanufacture. However, despite the growing trend around durability, there is no precise tracing of its evolution, implementation, and potential benefits from the product design stage. Therefore, this article aims to analyze the existing literature about durability and its relationship with the circular economy concept starting from the product design process, uncovering potential research directions, challenges, and trends for its application. A total of 147 articles were selected and analyzed from 40 years of research using two main approaches. First, a keyword-based analysis was used to identify trending topics around the concept of durability. Second, a content-based analysis was used, encompassing four main aspects: objectives and methodology; actors involved and lifecycle phases; circular economy strategies; and design phase, design attributes, and type of products involved. The analysis identified how the concept has evolved during the last four decades, indicating that future trends envisage methodologies, assessment tools, and guidelines to support product life extension.