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Currently, synthetic dyes are widely used to colour textile materials. However, safer and more sustainable bio-based alternatives are currently being explored. In this context, by-products and wastes from agricultural value chains have been investigated as potential sources of natural dyes. Nutshell wastes are promising because they are abundant, contain interesting dye molecules such as quinones and are easier to handle because of their low moisture content. Hence, the present study aims at exploring the potential of the extracts from the shells of peanut (Arachis hypogaea L.), cashew nut (Anacardium occidentale L.), coconut (Cocos nucifera L.) and macadamia nut (Macadamia integrifolia L.) to colour textile substrates. For this purpose, the nutshell colourants were extracted and then applied to wool fabrics. Then, the extracts were analysed for their total phenolic content using the Folin–Ciocalteu method; the extracts were qualitatively screened for the presence of quinone-based dye molecules. Next, the effect of the main dyeing parameters, such as pH and mordant concentrations, on K/S was assessed. After this, the dyeing kinetics, colourimetric properties, UV protection potential and environmental impact of using the dye were assessed. The phytochemical screening indicated the presence of phenolic compounds (within a range of 71.3 ± 1.7–1664.4 ± 7.7 mg GAE/100 g), confirming the presence of colouring compounds such as quinones. The dyeing process, at pH 3 for the cashew nut shell and pH 5 for the other nutshell extracts, gave the best K/S (0.6 ± 0.1–14.9 ± 1.0), while the mixed 1,2 order was the best model for describing dye wool adsorption. Also, a good resistance to washing (4–5), light (3–8) and staining (4–5) was achieved, even without the use of mordants. However, the use of mordants increased K/S and fastness properties. The nutshell extracts improved UV protection by up to 79%, with cashew nutshell extracts and FeSO4 mordants providing the best K/S and UV protection. Furthermore, the use of extract dye was about 60% environmentally friendlier compared with synthetic dyeing. Thus, the use of nutshell-based dyes can provide a clean and sustainable source of dyes that can be used to substitute for synthetic analogues.

Electronics require a complex composition and energy-intensive manufacturing. Yet, most of the world’s waste electrical and electronic equipment is not collected and recycled. Circular economy (CE) strategies can reduce the loss of materials and environmental footprint in electronics. Resource efficiency indicators – typically defined as benefits (handprint) over burdens (footprint) – can measure materials’ life cycle performance. This paper aims to develop resource efficiency indicators that show the benefits and burdens of materials use. We illustrated the indicators with a case study of four materials (aluminium, copper, iron, and plastics) embedded in laptops. The study includes scenarios with different CE strategies: energy recovery, recycling, refurbishing, and reuse. The scenarios show the use of the materials in several cycles of laptops over a 25-year time horizon. Generally, scenarios with cycles of refurbishment and reuse showed improved resource efficiency compared to recycling scenarios. Compared to energy recovery the improvement was up to 189% (refurbishment) and 157% (reuse) in the case of aluminium. Nonetheless, it is remarkable that the average resource efficiency results showed a preference for refurbishing over reuse during 25 years. The result is limited to a shorter functional inuse time of reused laptops. This analysis is relevant for a CE, where the value of materials should be kept for as long as possible. Our methodology expands the traditional one-cycle perspective by measuring the use of materials for 25 years. Policy-makers can use our indicators to assess CE strategies for several product cycles that keep materials in use lowering environmental impacts

Kick-off presentations at the Network-Wide Training Event 1 of C-PlaNeT EU H2020 project., This project has received funding from the European Union's Horizon 2020 research and innovation programme under the Marie Sklodowska-Curie grant agreement No. 859885.