A Circular Economy Strategy in the Canary Islands

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• #Research Article
• #Sustainability

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The study, published in the Journal of Cleaner Production, investigates the development of sustainable composite materials derived from plastic bottle caps and fibers from banana rachis waste, emphasizing their potential as a circular economy strategy for the Canary Islands. This research addresses critical waste management challenges in these outermost regions, characterized by limited recycling infrastructure and a heavy reliance on landfilling. The primary objective is to transform waste into valuable resources while enhancing environmental sustainability and economic viability.

Objectives and Context

The Canary Islands face significant waste management obstacles, with municipal recycling rates as low as 2%, and over 98% of waste directed to landfills. The abundance of agricultural byproducts, particularly banana rachis, alongside the high generation of plastic waste, presents a unique opportunity for innovation. This study explores the feasibility of blending plastics recovered from bottle caps with fibers extracted from banana rachis to create composite materials. These composites are intended as a sustainable alternative to high-density polyethylene (HDPE) and other traditional materials. The concept of a circular economy, which seeks to reduce waste and maximize resource efficiency by keeping materials in use for as long as possible, underpins this work. By transforming banana rachis and recovered plastics into sustainable composites, we contribute to global strategies for reducing environmental impacts and fostering sustainable development. This aligns with broader initiatives from ESCI-UPF’s UNESCO Chair, which actively promotes circular economy solutions across diverse sectors.

Materials and Methods

The study utilized a mixed plastic blend sourced from bottle caps collected through local recycling campaigns. These plastics primarily consisted of HDPE and polypropylene (PP), with minor traces of other polymers. Banana rachis fibers were manually extracted, treated with alkaline solutions to enhance their properties, and subsequently sun-dried. Both raw and treated fibers underwent rigorous chemical and mechanical characterization to assess their compatibility with polymer matrices.

Composite materials were manufactured by combining the plastic blends with 20-30% weight of banana fibers. A multi-kinetic mixing and injection molding process ensured uniform fiber distribution. The mechanical performance of the composites, including tensile, flexural, and impact properties, was evaluated in accordance with international standards (e.g., ISO 527). Additionally, cost analyses were conducted to determine the economic feasibility of the composites, considering raw material and processing costs.

Coupling agents use. A: Chemical interactions between the phases of a PE/PP/natural fiber composite adding coupling agents based on anhydride grafted polymers. B: SEM of a non-coupled composite. C: SEM of a coupled composite. / Image: ESCI-UPF’s UNESCO Chair (Journal of Cleaner Production)

Results and Discussion

The findings demonstrated that composites reinforced with banana rachis fibers exhibited superior mechanical properties compared to unreinforced plastic blends. At reinforcement levels of 30% by weight, the composites achieved higher tensile and flexural strength, showcasing the stiffening potential of banana rachis fibers. Notably, rachis fibers provided better reinforcement than pseudostem fibers due to their intrinsic strength and chemical composition.

The use of coupling agents such as maleic anhydride-functionalized polymers significantly improved the fiber-matrix interface, enhancing composite performance. For instance, the tensile strength of HDPE-based composites increased by up to 23.7% when treated fibers and coupling agents were incorporated. Flexural properties followed a similar trend, with reinforced composites showing enhanced durability and stiffness.

Economic analyses revealed that these composites are cost-competitive, particularly when reinforcement levels exceed 30%. The cost-effectiveness is attributed to the low acquisition cost of banana fibers and the added value derived from utilizing waste materials. Moreover, the study highlighted the environmental benefits of diverting significant volumes of plastic and agricultural waste from landfills, reducing greenhouse gas emissions, and fostering a circular economy by transforming waste into valuable resources. This approach also minimizes reliance on petroleum-derived polymers, contributing to long-term sustainability.

Conclusions and Implications

This research underscores the viability of integrating waste plastics and banana rachis fibers into composite materials, aligning with circular economy principles. The proposed approach not only addresses waste management issues in the Canary Islands but also provides a scalable model for other regions facing similar challenges. The successful application of these composites in local industries could reduce reliance on virgin plastics, decrease environmental pollution, and stimulate economic activity through waste valorization.

Future work should focus on scaling up production, optimizing fiber extraction processes, and exploring additional applications for these sustainable composites. By fostering collaborations between academia, industry, and policymakers, the Canary Islands could become a benchmark for innovative circular economy practices in isolated and resource-constrained regions.

This work is part of the initiatives led by the UNESCO Chair in Life Cycle and Climate Change at ESCI-UPF, in collaboration with the LEPAMAP-PRODIS Research Group at the University of Girona and the Mechanical Engineering Department of the University of Las Palmas de Gran Canaria. These partnerships highlight the importance of interdisciplinary and international cooperation in addressing global sustainability challenges. Additionally, this research has been developed within the framework of the CICEP project (R&D&I project TED2021-131039B-C33, funded by MCIN/AEI/10.13039/501100011033 and by the ‘European Union NextGenerationEU/PRTR), which seeks to foster circular economy solutions in the Canary Islands through innovative waste valorization strategies.