http://hdl.handle.net/10174/1027 2026-06-17T11:49:58Z http://hdl.handle.net/10174/42202 Title: Towards an ecological metaphor for regenerative circular economies Authors: Zisopoulos, Filippos; D. Fath, Brian; Meirelles de Oliveira, Bruno; Toboso-Chavero, Susana; D'Assenza-David, Hugo; Miranda de Souza, Vitor; Huang, Hao; Scrieciu, Serban; Clark, O. Grant; Noll, Dominik; Singh, Simron; Stefanakis, Alexandros; Boyd, Graham; Schraven, Daan; de Jong, Martin Abstract: An ecological metaphor can enable transitions towards regenerative circular economies. Yet, this potential remains latent because its conceptual development, which is a prerequisite for its practical operationalization, is in its incipient phase and largely vague. To strengthen its epistemological underpinning, we propose a forward-looking interdisciplinary research agenda which brings together theories, ontological positions, analytical approaches, and strategies of action from ecological economics, panarchy theory, socio-metabolic research, process ecology, environ network theory, the constructal law, nature-based solutions, complexity economics, doughnut economics, regenerative economics, and ergodicity economics. The agenda facilitates the concentration, consolidation, and acceleration of theoretical and methodological innovation for the generation and accumulation of a diverse yet coherent body of knowledge on the interpretation of the process of regeneration and for illuminating the ways in which regenerative circular economies may function. 2025-04-30T23:00:00Z http://hdl.handle.net/10174/42192 Title: Inequities blocking the path to circular economies: A bio-inspired network-based approach for assessing the sustainability of the global trade of waste metals Authors: Zisopoulos, Filippos; D. Fath, Brian; Toboso-Chavero, Susana; Huang, Hao; Schraven, Daan; Steuer, Benjamin; Stefanakis, Alexandros; Clark, O. Grant; Scrieciu, Serban; Singh, Simron; Noll, Dominik; de Jong, Martin Abstract: Considering the importance of waste metals for the transition to circular economies, this study follows a bio-inspired approach to evaluate their material and monetary global trade patterns for sustainability and equity. Between 2000 and 2022, the global trade grew by 5 % in trading countries, by 37 % in trade links, by 71 % in material flows, and by 569 % in economic flows. Driven by indirect effects, the average circulation of material and monetary flows ranged between 21.8–34.9 % depending on the demand or supply perspective but showed a declining trend. Due to homogenization, high network redundancy, and low network efficiency the trade remained robust yet outside the "window of vitality" characterizing natural ecosystems. A few, mostly high-income countries dominated the market, consolidating imports of high-value metal waste mostly from low- and middle-income exporters. Policies should address circularity and trade inequities, accounting for environmental and social ramifications throughout the lifecycle of products and materials. 2025-01-01T00:00:00Z http://hdl.handle.net/10174/42171 Title: Recycling Composite Food Packaging: Recovering and Valorization of Individual Components Authors: Mourão, Paulo; Coelho, David; Marques, Carolina; Assis, Carolina; Panizio, Roberta; Nobre, Catarina; Brito, Paulo Editors: Sérgio Brito, Paulo; Sanches Galvão, João; Almeida, Henrique; Rosa Ferreira, Liliana; Flores de Oliveira Gala, Pedro Abstract: Paper composite packaging, increasingly used in various sectors including food, offers benefits like enhanced product preservation. However, its recycling poses challenges due to the difficulty in separating its components, leading to waste accumulation in landfills or incineration. This work aims to develop a sustainable recycling strategy to address this environmental issue. The methodology was designed to investigate and assess the materials present in composite packaging, their compatibility with various solvents, and the feasibility of recovering packaging components such as paper, synthetic polymers, metals, and others. Additionally, the study aimed to recover solvents used in the process and determine the calorific value of the recycled samples. Using Hansen Solubility Parameters, we identified the most effective solvents for dissolving the composite food packages under analysis. Following solubilization, two samples (SL1’ and SH1’) were selected for further investigation, both dissolved using p-Cymene. These samples underwent FTIR-ATR and NMR analysis, that enabled the identification of specific polymers, including PE (Polyethylene), LDPE (Low-density polyethylene), HDPE (High-density polyethylene), PP (Polypropylene), and PC (Polycarbonate), present on those composite packaging. Furthermore, both samples were incinerated, and their calorific values were measured, ranging from 18.19 to 18.76 MJkg−1, demonstrating that they have potential for being valorized via energy recovery. 2025-01-01T00:00:00Z http://hdl.handle.net/10174/42170 Title: Taguchi Robust Design of Phase Transfer Catalytic Hydrolysis of Polyethylene Terephthalate (PET) Waste in Mild Conditions: Application for the Preparation of Metal–Organic Frameworks Authors: Asma Nouira, Asma Nouira; Imene Bekri-Abbes, Imene Bekri-Abbes; Cansado, Isabel; Mourão, Paulo Editors: Semsarilar, Mona; Ladmiral, Vincent Abstract: With the rapid increase in polyethylene terephthalate (PET) usage in recent years, recycling has become indispensable in mitigating environmental damage and safeguarding natural resources. In this context, this study presents a methodology for valorizing PET waste through phase transfer catalytic hydrolysis conducted at a low temperature (80 °C) and atmospheric pressure, with the goal of recovering the terephthalic acid (TPA) monomer. The recovered TPA monomer was subsequently utilized as a precursor for the synthesis of metal–organic frameworks (MOFs). Tributylhexadecyl phosphonium bromide (3Bu6DPB) was selected as the phase transfer catalyst due to its efficiency and sustainability. The process parameters, including the concentration of NaOH, the wt.% of catalyst to PET, and the concentration of PET in the solution, were varied to optimize the hydrolysis reaction. The Taguchi design methodology with an L9 (3^3) orthogonal array was employed to analyze the influence of these factors on the depolymerization time. The analysis of variance (ANOVA) results revealed that the concentration of NaOH was the most significant factor, contributing to 93.3% of the process efficiency, followed by the wt.% of the catalyst to PET (6.5%). The findings also demonstrated that the concentration of NaOH had the greatest impact (Δ = 4.27, rank = 1), while the concentration of PET had the smallest effect (Δ = 0.16, rank = 3). The optimal conditions for PET depolymerization were achieved in 75 min with 20 g/100 mL of NaOH, 12 wt.% of catalyst to PET, and 5 g/100 mL of PET. The recovered TPA monomer was further employed as an organic ligand to synthesize Fe(III)-TPA MOFs under mild conditions (80 °C for 24 h). The X-ray diffraction (XRD) analysis revealed the simultaneous formation of MOF-235(Fe) and MIL-101(Fe), two multifunctional materials with diverse properties and applications. This study highlights an efficient approach for producing low-cost MOFs while promoting urban waste recycling, contributing to an integrated strategy for PET recycling and resource valorization. 2025-03-01T00:00:00Z