Continuous catalytic epoxidation of biodiesel for sustainable production of bio-based plasticizers using molecular oxygen

The properties of bio-based plastics from microbial biomass and extracted microbial protein

Electrocatalytic oxidation of 5-hydroxymethylfurfural (HMF) to 2,5-furandicarboxylic acid (FDCA) offers a sustainable route to bio-based plastics that can replace petroleum-derived PET. Here, we systematically compare NiOOH and Fe-, Co-, and Cu-doped NiOOH electrocatalysts synthesized by pulsed electrodeposition with matched loadings and dopant distributions, enabling a direct one-to-one assessment of dopant effects on HMFOR in alkaline media. Among all catalysts, NiFeOOH delivers the highest activity and selectivity across the full potential range, reaching an FEFDCA of 87.42% and an FEHMFOR of 98.85% at 1.53 V versus reversible hydrogen electrode. Scaling the electrode area fivefold achieves near-quantitative HMF conversion (99.98%) with a 95.45% FDCA yield over 6 h while maintaining excellent durability. Mechanistic investigation via potential-dependent product analysis, in situ Raman spectroscopy, spontaneous kinetics, and density functional theory reveals dopant-specific functions: Fe strongly tunes the Ni3+ electronic structure to weaken Ni3+-O bonding, enhance substrate adsorption, and accelerate charge transfer; Co primarily increases electrochemical surface area, boosting site density but not intrinsic site reactivity; and Cu alters the rate-determining step, redirecting the reaction pathway. These insights show that different dopants offer distinct design levers in Ni-based HMF oxidation reaction (HMFOR) catalysts and motivate multidopant strategies to jointly tune electronic structure, morphology, and reaction pathways for improved performance.

Background: The transition from fossil-derived polymer additives to renewable alternatives is essential to mitigate environmental persistence and ensure chemical safety within the plastics industry. This review provides a comprehensive overview of recent developments in bio-based functional additives and their integration into circular economy frameworks. Methods: Following PRISMA guidelines, a systematic literature search was conducted using the Scopus database for studies published between 2023 and 2026. Search terms targeted bio-based plasticizers, flame retardants, antioxidants, and compatibilizers. Studies were screened against predefined inclusion criteria, specifically focusing on experimental validation in polymer matrices, while data mining was employed to map emerging research fronts. Results: From an initial 996 records, 54 studies were selected after removing duplicates and ineligible articles. The findings highlight a paradigm shift from passive physical fillers toward active, multifunctional macromolecular agents. Recent literature demonstrates that targeted molecular interventions, such as phosphorylated lignin and biomimetic structures, can resolve trade-offs between ductility and thermal stability at low loadings (<5 wt%). Synthesis routes, performance outcomes, and end-of-life trajectories for each additive class are summarized. Conclusions: Bio-based additives have evolved from simple substitutes into strategic tools for the molecular programming of sustainable polymers. Although challenges regarding scalability and high-temperature processing persist, their integration into circular economy strategies establishes a clear roadmap for next-generation bioplastics.

Plastic manufacturing depends heavily on petroleum-derived monomers like terephthalic acid, the main component of polyethylene terephthalate (PET). However, the depletion of fossil resources and increasing environmental concerns have heightened the need for sustainable alternatives. Lignocellulosic biomass has emerged as a promising resource due to its renewable, abundant, and eco-friendly nature. Understanding its chemical composition enables conversion of this biomass into platform chemicals, such as 2,5-furandicarboxylic acid (FDCA) and lactic acid, derived from cellulose and hemicellulose. These can be polymerized into bio-based plastics such as polyethylene furanoate (PEF), polylactic acid (PLA), and polyhydroxyalkanoates (PHAs), offering greener alternatives to fossil-based plastics. PEF features rigid furan rings that enhance thermal stability, mechanical strength, and barrier properties, and reduce gas permeability compared to PET. PLA is a renewable, biodegradable plastic widely used in packaging and medical applications. This review covers the chemical composition of lignocellulosic biomass cellulose, hemicellulose, and lignin, and various pretreatment strategies, chemical, physicochemical, and physical, to overcome biomass recalcitrance and improve conversion efficiency. It also highlights recent catalytic advances in transforming cellulosic carbohydrates into bio-based plastic precursors such as FDCA and lactic acid. Lastly, this review discusses polymerization pathways for producing PEF and PLA, emphasizing their role in reducing the environmental impact of polymer manufacturing and promoting green chemistry principles.

The increasing use of biodegradable plastics has raised new concerns about the potential health impact of their degradation products. Polylactic acid (PLA), one of the most widely used bio-based plastics, can rapidly fragment into micro- and nanoplastics (MPs/NPs), whose health effects are still poorly understood. Within the PRIN PNRR 2022 project PLASTAMINATION, the effects of PLA NPs (size ~170 ± 64 nm) on central nervous system (CNS) cellular models, and epithelial cells representing key components of the intestinal barrier were investigated. In CNS models, PLA NPs were efficiently internalized by both neuronal (PC12) and glial (C6) cells. In differentiating PC12 cells, PLA NPs exposure impaired NGF-induced neuronal differentiation, reducing neurite number and length, altering cell cycle progression, and downregulating ERK and AKT signaling, while increasing oxidative stress and pro-inflammatory cytokine release. In C6 glial cells, PLA NPs induced a reactive phenotype characterized by increased GFAP expression, AKT pathway activation, and elevated reactive oxygen species (ROS) levels. In parallel, in vitro studies on human intestinal Caco2 and HT29 cells also showed that PLA NPs can be internalized by the cells and PLA NPs exposure induced a significant increase in ROS production in both cell types, while HT29 cells also displayed enhanced release of the pro-inflammatory cytokines. Further investigations on differentiated Caco-2/HT29 co-cultures, set up to mimic the intestinal barrier, showed that chronic exposure to PLA NPs (100 µg/mL for 21 days) led to a persistent increase in transepithelial electrical resistance (TEER), associated with enhanced expression of tight junction proteins ZO-1 and E-cadherin in differentiated Caco2 cells while increasing mucin production in differentiated HT29 cells. These findings suggest a structural reinforcement of the epithelial barrier accompanied by oxidative stress and inflammatory signaling, suggesting an adaptive response that may evolve toward a chronic inflammatory condition. Untargeted metabolomic analyses supported the overall results indicating that PLA NPs can affect redox balance and nitrogen metabolism in C6 cells as well as glucose and lipid metabolism in HT29. Across both intestinal and CNS cellular models, PLA NPs exposure consistently induced oxidative stress and activation of inflammatory related pathways, in the absence of acute cytotoxicity. These shared responses suggest a common cellular stress signature triggered by PLA-derived NPs, despite tissue-specific functional outcomes. However, compared to intestinal epithelial cells, CNS cellular models seem to show more pronounced functional alterations. In particular, neuronal and glial cells displayed impaired differentiation, activation phenotypes, and marked changes in intracellular signaling, suggesting a higher sensitivity of neural cells to PLA NPs. Overall, these results demonstrate that PLA NPs can interact with intestinal and neural cells, inducing molecular and functional alterations. The findings highlight the need to carefully evaluate the long-term biological impact of biodegradable plastic-derived NPs to support truly sustainable plastic alternatives.Funding: This work was supported by the National Recovery and Resilience Plan (NRRP), Mission 4, Component 2, Investment 1.1, “Fund for the National Research Program and for Projects of National Interest (NRP)” by the Italian Ministry of University and Research (MUR), funded by the European Union – NextGenerationEU. Project title: “Plastic Contamination by Poly(Lactic Acid) (PLASTAMINATION): organ injuries and underlying molecular mechanisms”, MUR, PRIN- PNRR2022 CODE NUMBER: P2022AA47Y- CUP D53D23021910001.

In situ degradation of biodegradable bio-based plastics in urban soil: Pilot study for PLA, PHB, PHBH, and Bio-PBS in central Tokyo, Japan.

The inherent immiscibility of biodegradable aliphatic polyesters, such as poly(butylene succinate) (PBS) and poly(ε-caprolactone) (PCL), hampers the development of strong yet degradable plastics. Here, we demonstrate that random isodimorphic copolyesters, poly(butylene succinate-ran-ε-caprolactone) (BSxCLy), effectively compatibilize equimolar PBS/PCL blends through a matrix-driven crystallization mechanism that couples the two phases at the molecular level. Multiscale characterization, combining DSC, in situ and spatially resolved polarized FT-IR imaging, and nanobeam synchrotron WAXD/SAXS, reveals the first structural evidence of quadrant-specific spherulites, in which alternating quadrants exhibit distinct lamellar architectures: banded regions with continuous twisting and nonbanded regions with uniform orientation. This pronounced morphological anisotropy arises from the selective cocrystallization of BS-rich segments (within the random copolymer) with the PBS blend component and the formation of PBS β-form crystals with looser molecular packing. These features promote interfacial coupling and enhance degradability. The concept of matrix-directed crystallization establishes a potentially general framework for compatibilizing immiscible biodegradable polyesters and for designing biobased plastics with tunable crystalline hierarchy, mechanical performance, and controlled biodegradation behavior.

Abstract This study explores the development of polylactic acid (PLA) blends incorporating plasticized zein, a corn-derived protein, and dipropylene glycol (DPG) as a biobased plasticizer to enhance compatibility and processability. Blends were produced via twin-screw extrusion and injection molding, with plasticized zein content ranging from 10 to 50 wt%. Mechanical testing showed a significant increase in ductility, with elongation at break rising from 6.3% (neat PLA) to 56.3% (50 wt% zein), accompanied by reduced tensile strength (58.4 MPa to 22.7 MPa) and impact resistance (42.2 kJ/m 2 to 11.5 kJ/m 2 ), due to phase separation and limited compatibility. Shore D hardness slightly declined (from 82.9 to 77.4). Thermal analysis revealed the T g decreasing from 59.5 °C to 39.9 °C as zein content increased. Thermogravimetric analysis showed reduced thermal stability with zein addition, dropping the initial degradation temperature from 360.0 °C to 188.2 °C. Morphological analysis indicated greater heterogeneity at higher zein levels due to partial miscibility. Colorimetric data showed visible changes, and FTIR spectra confirmed physical interactions and partial miscibility between PLA and zein.

The increasing shift towards bio-based plastics is often promoted as a sustainable alternative to petroleum-based plastics; however, uncertainty remains over whether these materials truly offer environmental advantages across their entire life cycle. In this paper, the gap is addressed through a cradle-to-grave Life Cycle Assessment (LCA) of bio-based and petroleum-based plastic bottles, where 667 bottles (0.75 L each, equivalent to 50500 L of water) were used as the functional unit. The SimaPro model was applied to assess environmental impacts using the ReCiPe 2016 Endpoint H method, which encompasses the following categories: climate change, fossil resource depletion, land use, and water consumption. The results show that bio-based bottles reduced fossil resource depletion by 85% and lowered the potential for ionizing radiation by 12% compared to petroleum-based plastics. However, they performed worse in terms of land use (3.8 m²a crop eq. vs. 0.9 m²a crop eq.) and water consumption (29.4 m³ vs. 9.7 m³) due to agricultural feedstock production. Conversely, petroleum-based bottles had 15% higher global warming potential (1.8 kg CO₂-eq. vs. 1.56 kg CO₂-eq.) and significantly greater fossil resource demand, but lower agricultural burdens. The findings demonstrate that neither plastic type is universally superior: bio-based plastics mitigate fossil depletion and climate impacts, while petroleum-based plastics have lower land and water burdens. This implies that contextual preferences regarding material selection, innovative methods for producing bio-based plastics through farming, and advanced recycling of either system should be evaluated to achieve these results. The research provides policymakers and producers with factual data to inform negotiations on the trade-offs of sustainable packaging.

The need for a circular materials economy is driving the search for new biobased plastics with desirable performance. This study generated and characterized biopolymer composite films from microcrystalline cellulose (MCC) and a protein concentrate extracted from brewers' spent grain (BSG), the main by-product of the beer brewing industry. Selected ionic liquids (ILs) were used as solvents for gel casting due to their ability to dissolve cellulose and BSG protein. Formulations with 5:0, 5:1, 5:2.5 and 5:5 (%/% wt) MCC-to-BSG protein ratio were prepared in 1-ethyl-3-methylimidazolium diethyl phosphate, [Emim][DEP], and 1-ethyl-3-methylimidazolium dimethyl phosphate, [Emim][DMP]. The resulting gels were coagulated in water and dried by hot-pressing, generating translucent brown films. The films with 5:2.5 MCC-to-protein ratio had tensile strengths of 106 MPa ([Emim][DEP]) and 118 MPa ([Emim][DMP]), comparing favourably with major commercial packaging materials. The protein cellulose films provided excellent protection against ultraviolet (UV) light, achieving up to 96% blockage for both UV-B and UV-A radiation and exhibited expected thermal stability and moderate antioxidant properties. While addition of BSG protein increased the hydrophobicity of the films' surface and reduced water vapour transmission, the films remained hydrophilic and had high water vapour permeability (approx. 400 g m-2 h-1 at 50% relative humidity). Effective recovery of more than 90% of the alkyl phosphate ILs was demonstrated, with a minimum of six batch washes required to remove the majority of the ILs. This article is part of the discussion meeting issue 'Ionic liquids and the future of soft materials'.

Polyesters such as PET contribute substantially to global plastic waste, yet current recycling approaches are hindered by high energy demands, inefficient product separation, and limited valorization pathways. We report a one-pot "carbonylolysis" strategy that couples polyester depolymerization with in situ carbon-chain reconstruction, producing high-value C3+ carboxylic acids under relatively mild conditions (170 °C, 2 MPa CO). Using a Rh-iodide catalyst, PET is quantitatively converted to terephthalic acid (99%) and propionic acid (96%). Mechanistic studies show that ethylene glycol released from PET hydrolysis undergoes iodide-assisted elimination followed by Rh-catalyzed carbonylation. The method applies broadly to diverse polyester wastes, including textiles and bio-based plastics. Life-cycle assessment and techno-economic analysis reveal substantial gains in energy efficiency, carbon footprint reduction, and wastewater minimization over conventional recycling routes. By integrating molecular-level reconstruction into polyester recycling, carbonylolysis establishes a sustainable blueprint for converting waste polyesters into high-value carboxylic acid.

Plastics drive twin crises: persistent pollution and greenhouse gas emissions. Bio-based approaches using enzymes and microorganisms to depolymerise plastics and valorise monomers show promise but raise societal, ethical and regulatory questions central to Responsible Research and Innovation (RRI). In this Perspective, we reflect on RRI implications of bio-based plastic degradation, informed by stakeholder discussions across the plastics value chain and public engagement. We identify broad support alongside concerns about scalability, interaction with existing recycling, governance and containment of genetically modified organisms, management of additives and contaminants, and the roles of regulation and economic incentives in enabling adoption.

The rapid growth of plastic production and use has triggered major environmental and regulatory challenges, including waste management, microplastic pollution, and chemical safety. In recent years, the European Union (EU) has launched policies that increasingly define, classify, manage, and restrict plastics. At the same time, the emergence of biobased and biodegradable plastics has raised new questions about how these materials may be impacted by existing legislation. How emerging biobased polymers are defined and regulated across EU legislation and inconsistencies in definitions of key terms such as biobased, bioplastic, and chemical modification have been critically assessed. To support innovation, a simplified decision tree is presented — based on existing regulatory and scientific frameworks — enabling clearer classification of polymers and synthetic polymeric microparticles (commonly referred to as primary microplastic). Unlike existing decision trees, this framework also identifies which plastic regulations apply and from which a polymer may be exempted. Case studies of cellophane, PLA/PHA, protein-based polymers, lignin, biobased microcapsules, and rubber demonstrate how the decision tree can be applied in practice, revealing ambiguities and potential misinterpretations. Biobased plastics are not automatically exempt from regulation but are generally treated like conventional plastics unless they meet strict criteria. Harmonized definitions and life cycle thinking are essential to avoid misconceptions and regrettable substitutions. Practical guidance for scientists, material developers, and regulators to navigate the evolving field of biobased plastics in the context of the EU plastics policy landscape, and advance safe and sustainable polymer innovation is provided.

High-performance fully bio-based cellulose plastics through dual cross-linking with epoxidized linseed oil.

Microplastics (MP) derived from commodity plastics are considered a threat to ecosystems. Bio-based and biodegradable (BB-) plastics are proposed as eco-friendly alternatives to petroleum-based (PB-) plastics. However, studies on the effects of MP on the model organism Daphnia magna often report a wide range of effects for both PB- and BB-plastics. While different physical and chemical MP properties may contribute, other factors, such as differences in clonal sensitivities, are rarely considered. Additionally, only a few studies included a particle control to differentiate between effects caused by particles themselves and those specifically by MP. In this study, these knowledge gaps are addressed by (1) comparing the effects of PB-MP (PET) and two BB-MP (PBS, PLA) on the life-history and morphology of D. magna, and (2) examining the responses of two D. magna clones to chronic MP exposure (all MP < 20 µm), always including cellulose as a particle control, in a setup with reduced food availability to mimic real environmental scenarios. When comparing PB- to BB-MP, the latter caused similar adverse effects on survival and sublethal life-history traits, while cellulose had no effect or positive effects. We observed a similar concentration-dependent increase in mortality for both clones while data on sublethal parameters were significantly different between the clones. We conclude that particle controls and genetic variability are crucial parameters that should be considered in D. magna experiments and that MP effects need to be investigated under environmentally relevant conditions.

Sustainable innovation: Artificial Intelligence-assisted design of bio-based plastics

Polylactic acid (PLA) is one of the most widely studied biodegradable polymers, yet its adoption in high-performance applications remains limited by its intrinsic brittleness, low toughness, and poor thermal resistance. Considerable efforts have been devoted to overcoming these shortcomings, but achieving simultaneous improvements in strength, ductility, and heat resistance without sacrificing biodegradability remains a critical challenge. Here, we show a scalable strategy that integrates in situ fibrillation of poly(butylene adipate-co-terephthalate) (PBAT) with supercritical CO2-induced nanocrystals to overcome these limitations. The fibrillated PBAT phase provides a high surface-area morphology that enhances interfacial interactions and heterogeneous nucleation, while nanoscale nanocrystals formed under ambient scCO2 promote ductile deformation by enabling chain mobility that contrasts the brittleness typically induced by thermal annealing. The prepared PLA/PBAT composites exhibit superior tensile performance (71.0 MPa strength and 21.8% elongation), significantly elevated Vicat softening temperature (∼155 °C), and accelerated alkaline hydrolysis, thereby coupling great mechanical robustness with environmental degradability. This multiscale structural design not only surpasses traditional trade-offs in biodegradable polymers but also advances the development of biobased plastics that combine high functionality with a closed-loop sustainable lifecycle.

The catalytic oxidation of 5-hydroxymethylfurfural to 2,5-furandicarboxylic acid is a key step in the production of bio-based plastics but remains limited by sluggish multi-electron transfer kinetics across multiple reaction intermediates. In this study, we address this long-standing challenge by introducing a Mn-O-Co electron bridge within spinel CoMn2O4 to mediate and accelerate electron transfer. Through precise valence state regulation, we engineer a heterogeneous electron bridge dominated by Mn4+-O2--Co3+ linkages, enabling more efficient electron flow. Experimental characterization and theoretical calculations reveal that the incorporation of Mn4+ significantly enhances electron delocalization across the bridge. The empty eg orbitals of Mn4+ (t2g3eg0) serve as efficient electron acceptors, creating an energy-level gradient with Co3+ (t2g4eg2) that favors directional electron transfer. Simultaneously, Mn4+ strengthens metal-oxygen covalency, further improving electron mobility. This engineered electron bridge structure enables highly efficient cooperation across the full six-electron transfer pathway in 5-hydroxymethylfurfural oxidation, driven by a dynamic electron compensation mechanism. As a result, an 2,5-furandicarboxylic acid yield of 98.1% is achieved. This work offers a valuable theoretical foundation for understanding cooperative electron transfer in heterogeneous catalysis and provides a rational strategy for designing efficient electron bridge structures.

Crafting new materials using microbial biomass, such as fungal mycelium and bacterially synthesized biopolymers as building blocks, can be a very efficient solution for the post-petroleum polymers era, especially if they can be engineered in similar ways to conventional polymers. In this study, we used melt extrusion followed by molding processes to develop a biocomposite of mycelium from the non-pathogenic fungal strain Pleurotus ostreatus, grown on coffee-silverskin, and processed together with the bacterially synthesized polyhydroxybutyrate biopolymer and the bio-based plasticizer epoxide soybean oil methyl ester, the latter being important for efficient melt processing. The different amounts of the bacterial biopolymer and the fungal mycelium biomass affect the structural, mechanical, thermal, barrier, antioxidant, and overall migration properties, as well as the biodegradation of the developed biocomposites. Importantly, based on the TOPSIS performance analysis, we conclude that the most suitable composition to be used for eco-friendly food packaging is the one with 5 wt % mycelium/coffee silverskin biomass introduced in the plasticized polymer matrix. This novel composite biomaterial, derived from the fungal, bacterial, and plant kingdoms and processed using conventional plastic methods, paves the way for low-cost, sustainable biocomposites with broad application potential.