Discarded fishing gear accumulating in marine and coastal environments poses a significant threat to marine ecosystems, particularly in Mediterranean countries such as Greece, and is increasing at an alarming rate. Therefore, sustainable management and recycling strategies for abandoned fishing gear and waste fishing nets (WFNs) are urgently needed. This study investigates pyrolysis as a sustainable valorization approach for WFN. A critical first step involves identifying the polymeric composition of the collected nets. For this purpose, a comparative assessment of polymer identification characterization methods was performed on twelve visually distinct WFN samples, employing Fourier Transform Infrared Spectroscopy (FT-IR) and Differential Scanning Calorimetry (DSC), followed by GC/MS analysis of the pyrolysis products. According to the results, the WFN samples were identified as HDPE, PP, PA-6 and PA-6,6. Subsequently, the suitability of pyrolysis as a valorization strategy for WFN was evaluated in relation to the polymeric composition of the samples, using a laboratory-scale pyrolysis reactor. Pyrolysis of PA-6-based WFNs yielded more than 91 wt.% liquid products, with a high relative abundance of ε-caprolactam (51.6–61.8% r.a.), indicating strong potential for monomer recovery and further development toward closed-loop recycling. In contrast, pyrolysis proved less promising for the valorization of PA-6,6-based WFNs. Polyolefin-based WFNs yielded more than 88 wt.% hydrocarbon-rich liquid products, with potential valorization as fuel precursors.
Ordinary Portland cement (OPC) is associated with considerable energy demand for its production and accounts for approximately 8% of the global CO2 emissions. The extensive extraction of natural aggregates further undermines the sustainability of concrete. The use of supplementary cementitious materials (SCMs) as a partial replacement for clinker, along with improved material optimization, is considered a fundamental measure. Fly ash (FA), owing to its pozzolanic behavior and its positive influence on improving workability and long-term durability, is extensively utilized. Ultrafine fly ash (UFFA) contributes to improved packing density and microstructural refinement due to its finer particle size and enhanced reactivity, whereas fiber inclusion bridges micro- and macrocracks by promoting structural ductility. This study reviews and integrates the recent research on HVFA systems, UFFA-based cementitious binders, and fiber-reinforced cement-based composites. Based on the governing mechanisms of each component, this review develops a rational synthesis of their potential interactions and dosage-related limitations. Although the FA-UFFA, FA–fiber, and UFFA–fiber binary systems have been individually explored, their simultaneous integration (FA-UFFA–fiber) remains unexplored. Based on the synthesized evidence, a conceptual multi-scale interaction framework and a preliminary evidence-informed design window are proposed to illustrate the complementary interactions and potentially synergistic interactions among FA, UFFA, and fibers, thereby providing a mechanistic basis for future experimental investigations of FA-UFFA–fiber cementitious systems.
The transition from fossil-based plastics to bioplastics in food packaging requires not only technological advances but also coherent regulatory frameworks and economic support mechanisms. This review examines how policies, production costs, and industrial initiatives shape the large-scale adoption of biopolymers such as polylactic acid (PLA), polyhydroxyalkanoates (PHA), and starch-based materials. The regulatory comparison indicates substantial differences in legal scope and implementation across jurisdictions, while also showing that the existence of binding legislation does not by itself demonstrate bioplastic-specific circular-performance outcomes. Although the high production cost of bioplastics remains a major barrier to widespread implementation, strategies including agricultural residue valorization and green fiscal instruments may contribute to improving competitiveness. Overall, the evidence reviewed suggests that the transition toward sustainable food packaging depends on the combined development of material performance, regulatory coherence, industrial integration, and life-cycle accountability, highlighting the need for greater coordination across these dimensions.
Mechanical recycling of post-consumer poly(ethylene terephthalate)/high-density polyethylene (PET/HDPE) streams is limited by immiscibility and processing-sensitive behavior. A nominal 30 wt% PET/70 wt% HDPE blend was evaluated using a 2 × 3 factorial matrix combining maximum extrusion setpoints (Te: 235 and 260 °C) and maximum injection setpoints (Tinj: 200, 230, and 260 °C). Each processing combination was represented by one run from common bulk feedstocks. Tensile (n = 54) and flexural (n = 53) responses were compared using within-campaign specimen-level contrasts and descriptive multi-response scoring. The Te= 260 °C/Tinj= 200 °C condition produced the highest observed strength–stiffness response, with tensile strength of 32.5 ± 2.23 MPa, flexural strength of 49.2 ± 6.35 MPa, and flexural modulus of 1550 ± 143 MPa. At Tinj= 200 °C, phase-agnostic SEM analysis showed finer fracture-surface texture after extrusion at 260 °C. Charpy impact followed a different trend, with Te= 235 °C/Tinj= 200 °C giving the highest observed blend impact response. These results indicate distinct processing–performance relationships for static and impact behavior in the uncompatibilized post-consumer PET/HDPE blend and establish a baseline for further processing and compatibilization studies.
In Colombia, annual sugarcane bagasse (SCB) generation reaches 10.86 Mt, and the residue has a higher heating value (HHV) of approximately 13.0 MJ kg−1. This study evaluated SCB catalytic pyrolysis using natural clinoptilolite (CLI) modified by sulfuric acid (CLI-SA), phosphoric acid (CLI-PA), or ammonium chloride exchange (CLI-AC), with commercial ZSM-5 as a benchmark. A mild 2 vol.% H2O2 treatment was applied for 12 h at 25 °C primarily for biological stabilization and as a gentle oxidative wash; no quantitative delignification is claimed. Pyrolysis was conducted at 475 °C for 5 min under N2 (60 mL min−1) with 5 wt.% catalyst. CLI-PA achieved the highest bio-oil yield (65.1%) and estimated HHV (20.5 MJ kg−1), compared with 46.5% and 16.8 MJ kg−1 for ZSM-5 and approximately 16.4 MJ kg−1 for the thermal liquid. Targeted GC-MS/SIM profiles, interpreted semi-quantitatively, showed a toluene-normalized area of 28.989% for CLI-PA versus 7.287% for thermal pyrolysis; oxygenated products nevertheless remained substantial. A cradle-to-gate screening LCA (1 kg catalyst, OpenLCA/CML Baseline) showed ZSM-5/CLI-PA ratios of 6.00–6.50 across nine impact categories (mean 6.19), while the estimated catalyst-related cost was 42.95-fold higher for ZSM-5. These findings identify CLI-PA as a promising low-cost catalyst under the tested conditions, while catalyst structure, acid-site distribution, reuse, gas-phase products, and effluent treatment remain priorities for further validation.
