Search Results (1,927)

Polyethylene terephthalate (PET) is a widely used polymer whose accumulation in the environment poses a significant pollution challenge. This study explores the degradation of bis(2-hydroxyethyl) terephthalate (BHET) and terephthalic acid (TPA)—two monomers commonly produced during PET hydrolysis and widely used as intermediates in PET recycling—through Advanced Oxidation Processes (AOPs) employing KrCl (222 nm) and XeBr (283 nm) excimer lamps in the presence of hydrogen peroxide (H₂O₂). The effects of the H₂O₂/monomer mass ratio, initial monomer concentrations, and reaction volume on degradation efficiency were systematically evaluated. The results demonstrate that excimer lamp technology, particularly KrCl, holds promising potential for the effective degradation of both BHET and TPA, and thus represents a viable strategy for PET waste treatment. Full article

Background: this research presents an integrated approach to enhancing the sustainability of plastic bag supply chains in Indonesia by addressing critical issues related to ineffective post-consumer waste management and low recycling rates. The objective of this study is to develop a combined framework of material flow analysis (MFA) and sustainable supply chain planning to improve demand forecasting and inflow management across the plastic bag lifecycle. Method: the research adopts a quantitative method using the XGBoost algorithm for forecasting and is supported by a polymer-based MFA framework that maps material flows from production to end-of-life stages. Result: the findings indicate that while production processes achieve high efficiency with a yield of 89%, more than 60% of plastic bag waste remains unmanaged after use. Moreover, scenario analysis demonstrates that single interventions are insufficient to achieve circularity targets, whereas integrated strategies (e.g., reducing export volumes, enhancing waste collection, and improving recycling performance) are more effective in increasing recycling rates beyond 35%. Additionally, the study reveals that increasing domestic recycling capacity and minimizing dependency on exports can significantly reduce environmental leakage and strengthen local waste management systems. Conclusions: the study’s novelty lies in demonstrating how machine learning and material flow data can be synergized to inform circular supply chain decisions and regulatory planning. Full article

Wood polymer composites (WPCs) represent a rapidly growing class of sustainable materials, formed by combining lignocellulosic fibers with thermoplastic or thermoset polymeric matrices. This review summarizes the state of the art in WPC development, emphasizing the use of recyclable (or recycled) and biodegradable polymers as matrix materials. The integration of waste wood particles into the production of WPCs addresses global environmental challenges, including plastic pollution and deforestation, by offering an alternative to conventional wood-based and petroleum-based products. Key topics covered in the review include raw material sources, fiber pre-treatments, compatibilizers, mechanical performance, water absorption behavior, thermal stability and end-use applications. Full article

Carbon fiber (CF) and carbon fiber-reinforced polymers (CFRPs) are widely used in the aerospace, automotive, and energy sectors due to their high strength, stiffness, and low density. However, significant waste is generated during manufacturing and after the use of CFRPs. Traditional disposal methods like landfilling and incineration are unsustainable. CFRP machining processes, such as drilling and milling, produce fine chips and dust that are difficult to recycle due to their heterogeneity and contamination. This study investigates the oxidation behavior of CFRP drilling waste from two types of materials (tube and plate) under oxidative (non-inert) conditions. Thermogravimetric analysis (TGA) was performed from 200 °C to 800 °C to assess weight loss related to polymer degradation and carbon fiber integrity. Scanning electron microscopy (SEM) was used to analyze morphological changes and fiber damage. The optimal range for removing the polymer matrix without significant fiber degradation has been identified as 500–600 °C. At temperatures above 700 °C, notable surface and internal fiber damage occurred, along with nanostructure formation, which may pose health and environmental risks. The results show that partial fiber recovery is possible under ambient conditions, and this must be considered regarding the harmful risks to the human body if submicron particles are inhaled. This research supports sustainable CFRP recycling and fire hazard mitigation. Full article

This research demonstrates the potential of plant waste cellulose as a remarkable biomaterial for multilayer tablet formulation. Rice husks (RC) and orange peels (OC) were used as cellulose sources and characterized for a comparison with commercial cellulose. The FTIR characterization shows minimal differences in their chemical components, making them equivalent for compression into tablets containing ibuprofen. TGA measurements indicate that the RC is slightly better for multilayer formulations due to its favorable degradation profile. This is corroborated by an XRD analysis that reveals its higher crystalline fraction (~55%). The use of a heat press at combined high pressures and temperatures allows the layer-by-layer tablet formulation of ibuprofen, taken as a model drug. Additionally, this study compares the release profile of three types of tablets compressed with cellulose: mixed (MIX), two-layer (BL), and three-layer (TL). The MIX tablet shows a profile like that of conventional ibuprofen tablets. Although both BL and TL tablets significantly reduce their release percentage in the first hours, the TL ones have proven to be better in the long run. In fact, formulations made of extracted cellulose sandwiching ibuprofen display a zero-order release profile and prolonged release since the drug release amounts to ~70% after 120 h. This makes the TL formulations ideal for maintaining the therapeutic effect of the drug and improving patients’ wellbeing and compliance while reducing adverse effects. Full article

Food waste has emerged as a critical worldwide concern, resulting in environmental deterioration and economic detriment. Bio-based natural polymer coatings and films have emerged as a sustainable solution to food preservation challenges, particularly in reducing postharvest losses and extending shelf life. Compared to their synthetic counterparts, these polymers, such as chitosan, starch, cellulose, proteins, and alginate, are derived from renewable sources that are biodegradable, safe, and functional. Within this context, this review examines the various bio-based natural polymer coatings and films as biodegradable, edible alternatives to conventional packaging solutions. It examines the different fabrication methods, like solution casting, electrospinning, and spray coating, and incorporates antimicrobial agents to enhance performance. Emphasis is placed on their mechanical, barrier, and antimicrobial properties, their application in preserving fresh produce, how they promote food safety and environmental sustainability, and accompanying limitations. This review highlights the importance of bio-based natural polymer coatings and films as a promising, eco-friendly solution to enhancing food quality, safety, and shelf life while addressing global sustainability challenges. Full article

Plastic waste accumulation is one of the most pressing environmental challenges of the 21st century, owing to the widespread use of synthetic polymers and the limitations of conventional recycling methods. Among available strategies, chemical upcycling via depolymerization has emerged as a promising circular approach that converts plastic waste back into valuable monomers and chemical feedstocks. This article provides an in-depth narrative review of recent progress in the upcycling of major plastic types such as PET, PU, PS, and engineering plastics through thermal, chemical, catalytic, biological, and mechanochemical depolymerization methods. Each method is critically assessed in terms of efficiency, scalability, energy input, and environmental impact. Special attention is given to innovative catalyst systems, such as microsized MgO/SiO₂ and Co/CaO composites, and emerging enzymatic systems like engineered PETases and whole-cell biocatalysts that enable low-temperature, selective depolymerization. Furthermore, the conversion pathways of depolymerized products into high-purity monomers such as BHET, TPA, vanillin, and bisphenols are discussed with supporting case studies. The review also examines life cycle assessment (LCA) data, techno-economic analyses, and policy frameworks supporting the adoption of depolymerization-based recycling systems. Collectively, this work outlines the technical viability and sustainability benefits of depolymerization as a core pillar of plastic circularity and monomer recovery, offering a path forward for high-value material recirculation and waste minimization. Full article

The environmental burden of conventional plastics has sparked interest in sustainable alternatives such as polyhydroxyalkanoates (PHAs). However, despite ample research in bioprocess development and the use of inexpensive waste streams, production costs remain a barrier to widespread commercialization. Complementary to this, genetic engineering offers another avenue for improved productivity. Cupriavidus necator stands out as a model host for PHA production due to its substrate flexibility, high intracellular polymer accumulation, and tractability to genetic modification. This review delves into metabolic engineering strategies that have been developed to enhance the production of poly(3-hydroxybutyrate) (PHB) and related copolymers in C. necator. Strategies include the optimization of central carbon flux, redox and cofactor balancing, adaptation to oxygen-limiting conditions, and fine-tuning of granule-associated protein expression and the regulatory network. This is followed by outlining engineered pathways improving the synthesis of PHB copolymers, PHBV, PHBHHx, and other emerging variants, emphasizing genetic modifications enabling biosynthesis based on unrelated single-carbon sources. Among these, enzyme engineering strategies and the establishment of novel artificial pathways are widely discussed. In particular, this review offers a comprehensive overview of promising engineering strategies, serving as a resource for future strain development and positioning C. necator as a valuable microbial chassis for biopolymer production at an industrial scale. Full article

For the first time, electrospinning has been used to recycle polyacrylonitrile terpolymer (PAN) waste following the solid-phase N-methylmorpholine-N-oxide (NMMO) process from PAN solutions in DMSO into nonwoven materials. The morphology of the obtained material has been studied. The material derived from secondary raw materials was compared to the material from the original PAN using IR spectroscopy, X-ray diffraction, scanning electron microscopy, and atomic force microscopy. It has been demonstrated that the chemical changes of PAN that occur during NMMO processing do not interfere with nonwoven material manufacture. Spun PAN nonwovens with different histories have similar morphology. It has been shown that the elastic modulus of ultrafine fibers depends on the history of PAN. Single monofilaments produced from initial PAN have a threefold greater elastic modulus than fibers spun from NMMO-recycled polymer. The revealed structure and properties of PAN fibers allow them to be considered as filter materials, as well as precursors of carbon nonwoven fabrics. Full article

Antimicrobial food packaging with natural antimicrobials and biodegradable polymers presents an innovative solution to mitigate microbial contamination, prolong freshness, reduce food waste, and alleviate environmental burden. This study developed antimicrobial hemicellulose-based films by incorporating carvacrol (1% and 2%) as a natural antimicrobial agent through micro-emulsification produced by high-pressure homogenization (M-films). For comparison, films with the same formula were constructed using coarse emulsions (C-films) without high-pressure homogenization. These films were investigated for their antimicrobial efficacy, mechanical and barrier properties, and physicochemical attributes to explore their potential as sustainable antimicrobial packaging solutions. The M-films demonstrated superior antimicrobial activity, achieving reductions exceeding 4 Log CFU/mL against Listeria monocytogenes, Escherichia coli, and Salmonella enterica, compared to the C-films. High-pressure homogenization significantly reduced the emulsion’s particle size, from 11.59 to 2.55 μm, and considerably enhanced the M-film’s uniformity, hydrophobicity, and structural quality. Most importantly, the M-films exhibited lower oxygen transmission (35.14 cc/m²/day) and water vapor transmission rates (52.12 g/m²/day) than the C-films at 45.1 and 65.5 cc/m²/day, respectively, indicating superior protection against gas and moisture diffusion. Markedly improved mechanical properties, including foldability, toughness, and bubble-free surfaces, were also observed, making the M-films suitable for practical applications. This study highlights the potential of high-pressure homogenization as a method for enhancing the functional properties of hemicellulose-based films (i.e., M-films). The fabricated films offer a viable alternative to conventional plastic packaging, paving the way for safer and greener solutions tailored to modern industry needs. Full article

Plastics make up a significant proportion of the stream of the European Waste of Electric and Electronic Equipment (WEEE), yet the use of recycled plastic materials is very low in new manufactured products. A description of the WEEE waste stream in Europe is given, with a focus on the plastic materials commonly found in WEEE that include four principal polymers: polypropylene (PP), polycarbonate (PC), acrylonitrile-butadiene-styrene (ABS) and polystyrene (PS). Furthermore, the legislative aspects related to WEEE and plastics recycling in Europe are complex, and numerous norms have been dictated by the European Commission. These norms are crucial to the sector of polymer recycling and production in Europe. Moreover, an overview of the entire treatment chain is presented. More specifically, each step of a typical recycling chain is introduced, with a focus on the sorting of plastics and the separation of polymers. Lastly, the influence of contaminants in the plastic fraction is discussed, both in terms of polymer particles and unwanted additives. By showing the impact of the purity rate on the mechanical properties of recycled plastics, the consequences of inadequate end-of-life treatment for WEEE-plastics is highlighted, hence linking the quality of recycled plastics to the separation step and the re-compounding of recycled granulates. Full article

The growing environmental concerns associated with petroleum-based plastics require the development of sustainable, biodegradable alternatives. Polyhydroxyalkanoates (PHAs), a family of biodegradable bioplastics, offer a promising potential as eco-friendly substitutes due to their renewable origin and favorable degradation properties. This research investigates the use of synthetic condensate, mimicking the liquid fraction from drying and shredding of household food waste, as a viable substrate for PHA production using mixed microbial cultures. Two draw-fill reactors (DFRs) were operated under different feed organic concentrations (2.0 ± 0.5 and 3.8 ± 0.6 g COD/L), maintaining a consistent carbon-to-nitrogen ratio to selectively enrich microorganisms capable of accumulating PHAs through alternating nutrient availability and deficiency. Both reactors achieved efficient organic pollutant removal (>95% soluble COD removal), stable biomass growth, and optimal pH levels. Notably, the reactor with the higher organic load (DFR-2) demonstrated a modest increase in PHA accumulation (19.05 ± 7.18%) compared to the lower-loaded reactor (DFR-1; 15.19 ± 6.00%), alongside significantly enhanced biomass productivity. Polymer characterization revealed the formation of poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV), influenced by the substrate composition. Microbial community analysis showed an adaptive shift towards Proteobacteria dominance, signifying successful enrichment of effective PHA producers. Full article

The development of sustainable and functional nanocomposites has attracted considerable attention in recent years due to their broad spectrum of potential applications, including wood preservation. Also, a global goal is to reuse the large volumes of waste for environmental issues. In this context, the aim of the study was to obtain soda lignin particles, to graft ZnO nanoparticles onto their surface and to apply these hybrids, embedded into a biodegradable polymer matrix, as protection/preservation coating for oak wood. The organic–inorganic hybrids were characterized in terms of compositional, structural, thermal, and morphological properties that confirm the efficacy of soda lignin extraction and ZnO grafting by physical adsorption onto the decorating support and by weak interactions and coordination bonding between the components. The developed solution based on poly(3-hydroxybutyrate-co-3-hydroxyvalerate) and lignin-ZnO was applied to oak wood specimens by brushing, and the improvement in hydrophobicity (evaluated by water absorption that decreased by 48.8% more than wood, humidity tests where the treated sample had a humidity of 4.734% in comparison with 34.911% for control, and contact angle of 97.8° vs. 80.5° for untreated wood) and UV and fungal attack protection, while maintaining the color and aspect of specimens, was sustained. L.ZnO are well dispersed into the polymer matrix, ensuring a smooth and less porous wood surface. According to the results, the obtained wood coating using both a biodegradable polymeric matrix and a waste-based preservative can be applied for protection against weathering degradation factors, with limited water uptake and swelling of the wood, UV shielding, reduced wood discoloration and photo-degradation, effective protection against fungi, and esthetic quality. Full article

Carbon layer-coated μm-sized carbon fiber has the potential to be developed as an electrode, as it can be directly used as an electrode without any preparation process in the absence of an insulating binder. In our work, a carbon layer-coated carbon fiber (C@CF) coaxial structure is constructed by in situ conversion of the epoxy resin around the carbon fiber into a carbon layer, in which a sandwich scaffold of cover/CFRP/screen is designed and adopted. The activated SC@CF, i.e., A-SC@CF, can be directly served as the electrode, and has excellent supercapacitor performance: a high specific capacity of 227.1 F g⁻¹ at 0.5 A g⁻¹, with a capacitance retention of 98.9% after 20,000 cycles for the electrode, and an energy density of 16.68 Wh kg⁻¹ at the power density of 1400 W kg⁻¹ for its symmetrical supercapacitor (SSC). Full article

Electrostatic separation is a promising technology for the recovery of valuable metals from electronic waste, particularly from printed circuit boards (PCBs). This study explores the application of electrostatic separation for the selective recovery of metallic and non-metallic fractions from crushed PCBs (PCBs). The process exploits the differences in electrical properties between conductive metals and non-conductive polymers and ceramics, facilitating their separation through applied electric fields. The raw materials were pre-treated via mechanical comminution using shredders and hammer mills to achieve an optimal particle size distribution (<3 mm), which enhances separation efficiency. Ferrous materials were removed prior to electrostatic separation to improve process selectivity. Key operational parameters, including particle size, charge accumulation, environmental conditions, and separation efficiency, were systematically analysed. The results demonstrate that electrostatic separation effectively recovers high-value metals such as copper and gold while minimizing material losses. Additionally, the process contributes to the sustainability of e-waste recycling by enabling the recovery of non-metallic fractions for potential secondary applications. This work underscores the significance of electrostatic separation as a viable technique for e-waste management and highlights optimization strategies for enhancing its performance in large-scale recycling operations. Full article