This study presents a circular valorization strategy for Tenebrio molitor (TM) farming residues through the production of high value biopolymers : chitin and chitosan. All insect farming waste streams, including larval and adult residues, were subjected to an optimized extraction protocol. An initial process (P1) was developed to recover chitin from both exuviae and adult cuticle. However, spectroscopic and morphological characterizations revealed the presence of lipid residues in the extracted chitin particularly in larval materials affecting its physicochemical integrity. A delipidation step was therefore introduced to purify the material and obtain α-chitin of higher structural quality. Building on these findings, an improved and simplified protocol (P2) was developed to enable more efficient recovery. This process allowed the extraction of pure, delipidated, and highly deproteinized α-chitin, closely resembling the native structure. Chitin yields ranged from 27.0% to 27.5% for the two larval exuviae stages and reached 30.0% for the adult residues. The extracted biopolymers were then converted into chitosan by N-deacetylation using Kurita’s and Broussignac’s methods, resulting in highly deacetylated chitosan (2% ≤ DA ≤ 12%) with controlled viscometric molar masses (Mv). Comprehensive structural and physicochemical characterizations were performed using FTIR, XRD, SEM, ¹H NMR, and viscosimetry. These analyses confirmed the purity, molecular integrity, and functionality of the obtained biopolymers.Due to their versatile chemical and biological properties, these materials hold strong potential for applications in cosmetics, biomedicine, and wastewater treatment supporting a sustainable circular bioeconomy.

The rising concern over plastic pollution and its long-term environmental consequences has intensified global efforts to discover sustainable alternatives to conventional synthetic polymers. In this study, we report on the development of fully bio-based dynamic polyester covalent adaptable networks (CANs), synthesized from renewable and environmentally friendly resources. These advanced polymeric systems incorporate dynamic covalent bonds that enable reversible chemical transformations, allowing the materials to be reprocessed, recycled, and even self-healed. Such features make them particularly attractive for sustainable material applications. This approach directly addresses the escalating accumulation of plastic waste, aiming to minimize its adverse impact on both the environment and human health. The polyester CANs developed here demonstrate adequate mechanical strength and can be reprocessed multiple times under mild conditions without significant loss of performance. Comprehensive material characterization confirms their structural integrity and adaptability across repeated recycling cycles. This work represents a significant advancement in polymer science, offering a pathway to reduce plastic waste while enhancing the functionality and lifecycle of materials. The findings underscore the potential of integrating bio-based sources with dynamic bonding strategies to create smart, durable polymers that align with circular economy principles. Overall, this study offers valuable insights into developing the next generation of environmentally responsible materials.

The close-to-market Life Restart project, co-financed by the European Union (LIFE Program for the Environment and Climate Action), focuses on recycling agri-food waste to produce biodegradable bio composites within a “green” and circular economy framework ^[1].

The project aims to recover and reuse 75% of a major beer production by-product (brewer's spent grains—BSG), while reducing the consumption of fossil-based polymers by 15% and virgin biopolymers by 35%. This approach promotes the use of bioplastics (bio-derived/bio-degradable) instead of fossil-based alternatives, as well as the re-use of waste products from the agri-food chain, to contribute to the achievement of carbon neutrality and “net zero emissions” by 2050 ^[2].

In this study, bioplastics are mixed with agri-food waste (brewer spent grain, BSG), to create bio-compounds. We evaluated the mechanical performance of various bioplastics (bio-derived and/or biodegradable) to produce bioplastic–waste mixtures ^[3]. This approach transforms waste into a valuable resource within the framework of a circular economy. By incorporating BSG, the process reduces the amount of bioplastic required, lowering production costs, as bioplastics are significantly more expensive than fossil-based plastics.

As part of the project, partners and stakeholders have developed the first prototypes of different objects, with different processing technologies (such as injection molding, extrusion, melt-mixing, 3D printing) by using these bio-compound mixtures. The mechanical tensile performance of some objects made from bioplastic–waste mixtures was analyzed and compared to that of objects formed from pure bioplastic and to that of fossil-based plastics. We focused on plant pots, in particular, as an example object. The results showed that the bio-compounds made from thebioplastic–waste mixtures exhibit good mechanical tensile strength compared to commercial pots, with the additional advantage of their biodegradability ensuring a fully sustainable product life cycle.

Several other physical, mechanical, rheological, and morphological characterizations of the bioplastic–waste mixtures, before and after degradation (photo-degradation and thermo-mechanical degradation), have been studied.

The fishery supply chain, encompassing fishing and aquaculture, processing, preservation, and marketing of fish products, relies extensively on plastic materials. Items such as fishing nets, crates, containers, mussel nets, and packaging are essential for daily operations, but their widespread use contributes significantly to marine litter and environmental pollution. Among them, discarded fishing nets are of particular concern, as they are typically produced from oil-derived polymers and represent a persistent source of plastic waste in marine ecosystems.

In recent years, the development of recycling technologies, especially mechanical recycling, has offered promising solutions to recover these materials and reintegrate them into new production cycles, supporting the transition toward a circular economy.

In this study, fishing nets made of polypropylene (PP) were collected and mechanically recycled. Post-consumer nets were blended with virgin PP to obtain formulations containing 10 wt% and 30 wt% of recycled material. These blends were processed by extrusion and subjected to rheological, morphological, and mechanical characterization in order to evaluate their processability and to assess their suitability for new applications.

The results demonstrate that recycled PP fishing nets can be effectively reprocessed and valorized as secondary raw materials, highlighting their potential for the development of sustainable polymer systems suitable for different applications, thereby reducing reliance on virgin plastics and mitigating environmental impacts.

Ecological and flexible polymeric nanocomposites are essential for sustainable development, considering their technological potential for the production of new materials with enhanced and multifunctional properties. At the same time, they help mitigate environmental impacts, thereby promoting innovation in packaging, electronics, and other applications, as well as assisting in the transition to a greener and more circular economy. In this study, poly(lactic acid) (PLA)/poly(butylene adipate-co-terephthalate) grafted with glycidyl methacrylate (PBAT-g-GMA) nanocomposites were processed by extrusion and injection molded, using multi-walled carbon nanotubes (MWCNT) as conductive fillers. The tested MWCNT contents were 0.5, 1.0, 3.0, and 5 parts per hundred resin (phr) in the PLA/PBAT-g-GMA (70/30% by weight) system, aiming to evaluate impact strength, tensile strength, Shore D hardness, electrical conductivity, and morphological evolution by scanning electron microscopy (SEM). The use of 30% PBAT-g-GMA in the PLA matrix significantly increased impact strength by 556%, suggesting an improvement in the toughening process. Pure PLA and the PLA/PBAT-g-GMA blend exhibited typical insulating behavior, with electrical conductivity around 3.1 x 10⁻¹¹ S/cm. The incorporation of MWCNT into PLA/PBAT-g-GMA markedly enhanced the impact strength of the nanocomposites, especially at 5 phr, with a gain of 1085% compared to pure PLA. Furthermore, a transition to a semiconducting material occurred in the PLA/PBAT-g-GMA/MWCNT (5 phr) nanocomposite, with an electrical conductivity of 4.31 x 10⁻⁶ S/cm. In contrast, no improvements were observed in Shore D hardness and the elastic modulus of the nanocomposites. This behavior was explained by the preferential migration of carbon nanotubes to PBAT-g-GMA, promoting greater stability in the morphology and refinement of the dispersed phase in the PLA matrix, justifying the significant gain in impact strength. The results indicate potential as a flexible and conductive nanocomposite for antistatic applications.

The global production of synthetic polymers now exceeds 400 million tons annually, yet limited recycling efforts are projected to result in 12,000 million tons of plastic waste in landfills by 2050. Among the various recycling approaches, dissolution/precipitation methods offer promising potential, particularly for complex, hard-to-recycle polymer mixtures. Despite this, these methods are often overlooked and commonly rely on traditional organic solvents. Eutectic solvents (ES) represent a promising, greener alternative, though their development is complicated by the vast diversity of potential hydrogen bond acceptors (HBA) and donors (HBD).

This study leverages the COnductor-like Screening MOdel for Realistic Solvents (COSMO-RS) to identify selective and effective ES for dissolving complex mixtures of fossil-based polymers—such as polyethylene (PE), poly(ethylene terephthalate) (PET), polypropylene (PP), and poly(vinyl chloride) (PVC)—as well as commercial bio-based polymers like poly(lactic acid) (PLA). Using COSMO-RS, infinite dilution activity coefficients were calculated for 40 HBA and 59 HBD, generating 2,360 ES at 100 °C. These predictions were validated with experimental solubilization tests.

The results indicate hydrophobic ES with long-chain alcohols effectively dissolve PE and PP, while ES with phenolic monoterpenes dissolve PET and PLA efficiently. Overall, this work highlights the critical role of rational ES selection in advancing sustainable recycling processes for complex polymer mixtures as for multilayer films.

This work was developed within the scope of the project CICECO-Aveiro Institute of Materials, UIDB/50011/2020 (DOI:10.54499/UIDB/50011/2020), UIDP/50011/2020 (DOI:10.54499/UIDP/50011/2020) & LA/P/0006/2020 (DOI:10.54499/LA/P/0006/2020), financed by national funds through the FCT/MCTES (PIDDAC). This work is funded by national funds through FCT – Fundação para a Ciência e a Tecnologia, I.P., under the project GREEN-PATH (Ref. 2023.15169.PEX, DOI:10.54499/2023.15169.PEX). MISA acknowledges FCT for the Ph.D.grant PRT/BD/154714/2023. AMF and AFS acknowledge FCT for the research contracts CEECIND/00361/2022 (DOI:10.54499/2022.00361.CEECIND/CP1720/CT002) and CEECINSTLA/00002/2022, respectively.

PVC occupies a leading position among thermoplastics in terms of production and application. The main part of PVC is used in the form of plasticized products. The search for alternatives to phthalate plasticizers remains an urgent task, with priority given to materials with low toxicity and migration resistance. Saturated polyesters based on sebacic acid are a promising eco-friendly substitute. The development of PVC materials with such polyesters solves the problems of environmental safety, durability of products and compliance with international standards. Plasticization of polyvinyl chloride was carried out with DOР and polyethylene glycerol sebacinate containing terminal hydroxy and carboxyl groups, 50 wt. h. and 10 wt.h. respectively per 100 wt.h. PVC. The physico-chemical, technological and operational characteristics of plasticized PVC are determined. The tensile strength was 19.7 MРa, the elongation of PVC plastics was determined at a closing rate of 100 mm/min - 367%. The melt flow rate was determined on a plastometer (T=190 °C, P=98 Н): MFI = 64.5 g/10min. The thermal stability of the Congo red (185 °C) method was 209 min. The glass transition temperature was determined by the DMA method in the stretching mode and in the temperature range from minus 100 °C to plus 100 °C at a frequency of 1 Hz in a nitrogen atmosphere: -26.5 °C. An increase in the amount of polyester (20 wt.h.) leads to increased resistance to migration to polar and nonpolar environments, increased thermal stability – 211 min, MFI – 188 g/min.

Every year, huge amounts of natural waste are produced by various industries. In the current raw materials crisis, particular attention should be paid to the possibility of reusing them instead of disposing of them. After appropriate processing of natural raw materials, e.g., through alkalization or the addition of modifiers, they can be successfully used as fillers for plastics. Adding them to bio-based polylactide enables the production of composites with new properties that are also environmentally friendly.
In this study, several plant-based wastes were selected as fillers: straw, grass, reed, sunflower husk, as well as raspberry, evening primrose, and milk thistle pomaces. The raw materials were subjected to grinding, alkalization, and rinsing to neutralize the pH. Before further processing, the fibers were dried to remove residual solvents and moisture.
Concentrates with 20 wt% filler content were obtained by mixing PLA with the plant-based fillers in the molten state. The resulting materials were crushed using a knife granulator, and the granules were processed via injection molding. Ultimately, samples containing 5, 10, and 20 wt% of filler were produced.
To characterize the PLA composites, melt flow index (MFI) measurements, FT-IR spectroscopy, thermal analysis, and mechanical tests (tensile and flexural strength and impact strength) were performed. The results allow the assessment of flowability, processing behavior, and the basic mechanical and structural properties of the obtained composites. In this work, particular emphasis is placed on the properties of composites containing grass filler.

Research conducted under the project M-ERA.NET 3 call 2022 “Multifunctional materials based on polylactide” No. M-ERA.NET3/2022/73/PolyBioMat/2023 funded by the National Center for Research and Development.

In Colombia, annual plastic consumption reaches nearly 1.2 million tons, generating a significant impact on the environment and public health, as most of this waste ends up in landfills that pollute mangroves, rivers, and seas. To address the problems associated with non-biodegradable and non-renewable plastics, alternative materials such as biodegradable and non-toxic polymers have been promoted, among which polyhydroxyalkanoates (PHA) stand out. These microbially derived biopolymers are biocompatible, can be produced from various renewable carbon sources, and are suitable for both single-use plastics and biomedical applications, making them consistent with circular economy principles.

This study aimed to evaluate PHA production by Bacillus thuringiensis (C01) using starch and carboxymethylcellulose (CMC) as carbon sources, and to optimize the process through a central composite design with response surface methodology. Initially, fermentation growth variables were assessed using glucose as a control, followed by evaluation of the experimental substrates under optimized conditions. With CMC, a PHA production of 0.09 g/L was obtained, with a yield of 49.5% (w/w). In contrast, optimization with starch (14.168 g/L starch, 3.616 g/L ammonium sulfate, yeast extract in a 1:1 ratio, and an inoculum of approximately 6×10⁸ CFU/mL) resulted in 3.71 g/L biomass and 2.78 g/L PHA, corresponding to a yield of 74.9% (w/w). These findings demonstrate the ability of Bacillus thuringiensis to degrade starch and channel it into PHA synthesis.

FTIR, TGA, DSC, and MALDI-TOF analyses confirmed that the biopolymer obtained was poly-3-hydroxybutyrate (P(3HB)). In conclusion, the amylolytic activity of Bacillus thuringiensis highlights its potential for using starch-rich agroindustrial residues as substrates for sustainable PHA production.

Aromatic spent, a low-value industrial byproduct generated during the processing of essential oils, is typically discarded or utilized in low-end applications such as mulch, animal fodder, incense sticks, soaps, mosquito repellents, cosmetics, and as raw material in paper and particle board manufacturing. However, this biomass is an excellent source of cellulose—a component that remains largely underutilized. In this study, an effort was made to extract cellulose from lemongrass spent for the development of biodegradable films, offering a sustainable alternative to petrochemical-based packaging materials, which are known to harm the environment. The process began with a series of unit operations, including the size reduction, cleaning, drying, grinding, and sieving of the spent material. Chemical treatments involving alkaline and acid solutions, followed by bleaching, were employed to remove lignin and hemicellulose, thereby isolating purified cellulose. This purified cellulose was then subjected to acid hydrolysis to obtain cellulose nanocrystals (CNCs). The CNCs were incorporated into a film-forming solution consisting of chitosan and glycerol in optimized proportions. The mixture was homogenized and solvent-cast onto a 300×300 mm² polypropylene sheet. Upon drying at ambient conditions, transparent films of 42 microns were obtained. To evaluate the biodegradability of the developed CNC–chitosan–glycerol films, soil burial tests were conducted. Results showed approximately 70% degradation within 15 days, demonstrating their eco-friendly nature. The nano-scale dimensions of the cellulose nanocrystals were confirmed using Atomic Force Microscopy (AFM) and Scanning Electron Microscopy (SEM). Additionally, SEM analysis of the films was performed to check for any agglomeration of CNCs within the polymeric matrix. This study highlights the potential of aromatic spent as a sustainable resource for developing biodegradable packaging materials, contributing to environmental conservation and waste valorization.