Circular Economy

Microb Cell Fact. 2026 Jul 15. doi: 10.1186/s12934-026-03066-y. Online ahead of print.

ABSTRACT

BACKGROUND: Keratin-rich waste such as wool and feather wastes are generated in large quantities worldwide and remain difficult to valorize due to the structural resilience of keratin, that is reinforced by disulfide bonds. Microbial degradation offers a sustainable approach for converting these wastes into value-added products. In this study, keratin-degrading fungi were isolated from garden soils amended with wool pellets used as organic fertilizer. Three fungal strains showing keratinolytic activity were selected based on halo formation on keratin-containing agar media. Among them, Simplicillium aogashimaense was chosen for detailed characterization due to its non-pathogenic status, limited representation in the literature, and the absence of previously reported proteolytic or keratinolytic activity.

RESULTS: Feather meal degradation by S. aogashimaense was investigated during 12 days of submerged cultivation. The strain demonstrated strong keratinolytic potential, achieving up to 80% feather meal mass reduction. Biochemical analysis of the resulting hydrolysates, including protease activity, elemental composition, amino acid profiles, ammonium and sulfur concentrations, pH dynamics, and overall biochemical profile, revealed a multiphasic degradation pattern. The initial phase (days 1-3) was characterized by rapid feather breakdown, elevated protease activity, ammonium release, and preferential liberation of surface-accessible amino acids, indicating efficient enzymatic attack on exposed keratin domains. The intermediate phase (days 4-6) during which general protease activity declines along with the fungal biomass. This period is likely to correspond to a shift from feather degradation to assimilation and intracellular metabolism. During the final phase (days 7-12), measured parameters stabilized, consistent with maximal substrate degradation and subsequent assimilation of soluble hydrolysis products by the fungus.

CONCLUSIONS: This study provides the first evidence that S. aogashimaense exhibits keratin-degrading capability, identifying it as a previously unrecognized keratinolytic fungal species. These findings broaden current understanding of fungal keratin degradation and highlight the potential of S. aogashimaense for sustainable bioconversion of feather waste and other keratin-rich residues. Further optimization and mechanistic investigation of its enzymatic system may support future biotechnological applications in waste valorization.

PMID:42458517 | DOI:10.1186/s12934-026-03066-y

RSC Adv. 2026 Jul 15. doi: 10.1039/d6ra03514k. Online ahead of print.

ABSTRACT

The escalating global cancer burden, particularly in low- and middle-income countries, necessitates safer and more effective therapeutic strategies. The toxicity and environmental issues of traditional heavy-metal-based quantum dots (QDs) have been addressed by green-synthesised QDs, which have become a promising platform for nanomedicine. In photodynamic treatment (PDT), photothermal therapy (PTT), and theranostic applications, the anticancer effectiveness of green-synthesized QDs that are derived from plant extracts, microbes, biomolecules, and biomass waste is critically assessed. Green synthesis techniques, such as hydrothermal and microwave-assisted methods, provide biocompatible QDs with good photostability, tunable optical characteristics, and decreased cytotoxicity. Mechanistically, these QDs generate reactive oxygen species (ROS), induce mitochondrial dysfunction, produce localized hyperthermia upon near-infrared irradiation, and activate apoptotic pathways (such as p53, Bax/Bcl-2, and caspase cascade), leading to selective cancer cell death. Preclinical in vitro and in vivo studies demonstrate potent tumor ablation through passive (EPR effect) and active targeting strategies. Despite these advances, some key setbacks hinder their clinical translation: lack of standardized synthesis protocols, batch-to-batch variability, limited long-term biosafety data, suboptimal targeting efficiency, and regulatory hurdles. Future perspectives include AI-driven optimization, smart theranostic platforms integrating multimodal imaging and therapy, and sustainable circular economy approaches using biowaste. Addressing these challenges through harmonized protocols and rigorous preclinical validation will be essential to realize the full potential of green-synthesized QDs as safe, multifunctional, and effective cancer nanomedicines.

PMID:42459718 | PMC:PMC13370744 | DOI:10.1039/d6ra03514k

Foods. 2026 Jun 25;15(13):2274. doi: 10.3390/foods15132274.

ABSTRACT

The global agricultural sector faces the dual challenge of increasing productivity while mitigating environmental impacts caused by synthetic agrochemicals and massive agro-industrial waste. This review examines the transition to "Biostimulants 4.0," a circular economy paradigm driven by the valorization of biomass residues into high-value biological inputs through nanotechnology and Artificial Intelligence (AI). Our analysis highlights that green extraction methods, specifically enzymatic hydrolysis, preserve bioactive integrity and reduce carbon emissions by up to 23.2 times compared to synthetic nitrogen production. Furthermore, waste-derived formulations and nanoscale smart-delivery systems dramatically enhance crop performance; for instance, chitosan nanoparticles can achieve up to a 471% increase in specific growth metrics through sustained-release pathways. To move the industry beyond empirical trial-and-error, the integration of AI-driven predictive models now achieves up to 87% accuracy in forecasting biostimulant efficacy. Finally, we contrast global regulatory frameworks and evaluate the monetization of biostimulant-driven carbon sequestration, capable of generating high-integrity credits priced up to $35 per tonne, as a critical economic pathway to accelerate commercial adoption and incentivize a resilient, decarbonized agricultural system.

PMID:42450393 | DOI:10.3390/foods15132274

Int J Mol Sci. 2026 Jun 26;27(13):5788. doi: 10.3390/ijms27135788.

ABSTRACT

Moringa oleifera seed cake is the byproduct of moringa oil extraction and the most valuable source of 4-(α-L-rhamnosyloxy)benzyl glucosinolate (glucomoringin; GMG), the precursor of 4-(α-L-rhamnosyloxy)benzyl isothiocyanate (moringin; GMG+M). The vascular fungus Fusarium oxysporum f. sp. lycopersici (FOL) is an important soil-borne pathogen of tomato in cultivated areas worldwide. Coating seeds with phytochemicals has been reported to prevent seed transmission and control seedling infection. In this work, GMG was extracted and purified from moringa seed cake on the multigram scale, and GMG+M solutions obtained through controlled hydrolysis of the precursor with commercial myrosinase were evaluated against the pathogen both in vitro and in planta. FOL conidia germination and mycelial growth were significantly inhibited by GMG+M solutions in the range 1-1000 µM, in a dose-dependent manner, compared to GMG and control treatments, which did not differ significantly. Interestingly, the coating of tomato var. crovarese seeds with GMG or GMG+M (100 µM) resulted in equally effective reduction (70%) of the disease severity in post-emergence, suggesting a plant-mediated mechanism underlying the efficacy of the intact glucosinolate. Seed coating with both phytochemicals triggered polyphenol oxidase (PPO) activity in five-day-old tomato sprouted rootlets. This study highlighted the potential biotechnological value of M. oleifera seedcake for the development of a sustainable biopesticide.

PMID:42450057 | DOI:10.3390/ijms27135788

Molecules. 2026 Jun 24;31(13):2222. doi: 10.3390/molecules31132222.

ABSTRACT

The increasing occurrence of pharmaceutical contaminants in aquatic environments has intensified the demand for sustainable and cost-effective water treatment technologies. This study investigated the conversion of potato peel waste into carbonaceous adsorbents through hydrothermal carbonization (HTC) and conventional pyrolysis (PRYR) for the removal of carbamazepine (CBZ) from synthetic wastewater. Hydrochars and biochars were synthesized under varying processing conditions and characterized using scanning electron microscopy (SEM), Fourier-transform infrared spectroscopy (FTIR), elemental analysis, and Brunauer-Emmett-Teller (BET) surface area analysis. Adsorption experiments were conducted using a 50 mg/L CBZ solution at pH 6, room temperature, and an adsorbent dosage of 1 g/L. The adsorption performance was evaluated after short contact times to assess rapid-removal capability. HTC-derived hydrochars exhibited significantly superior performance compared with pyrolysis-derived biochars, achieving up to 97% CBZ removal and adsorption capacities approaching 50 mg g^-1 within 1 min of contact. In contrast, pyrolysis-derived biochars achieved removal efficiencies between approximately 7 and 55% under similar conditions. Correlation analysis between adsorption behaviour and physicochemical properties revealed that adsorption performance was more strongly influenced by surface chemistry, aromaticity, and mesoporosity than by BET surface area alone. FTIR analysis suggested that hydrogen bonding, π-π electron donor-acceptor interactions, and pore filling contributed to CBZ adsorption. HTC hydrochars retained abundant oxygen-containing functional groups that promoted rapid and stable adsorption, whereas pyrolysis-derived biochars exhibited weaker adsorption interactions despite possessing higher surface areas. The findings demonstrate that hydrothermal carbonization provides an effective low-temperature route for valorising potato peel waste into efficient adsorbents for rapid pharmaceutical removal from water and highlight the critical role of adsorbent surface chemistry in determining adsorption performance.

PMID:42451593 | DOI:10.3390/molecules31132222

Foods. 2026 Jul 7;15(13):2406. doi: 10.3390/foods15132406.

ABSTRACT

This review critically analyzes bioactive compounds derived from agro-industrial by-products, including polyphenols, natural pigments, dietary fiber, prebiotics, lipids, proteins, and bioactive peptides. The review examines their chemical characteristics, major agro-industrial sources, and recovery strategies, highlighting both conventional technologies and emerging green technologies, such as ultrasound-assisted extraction, supercritical fluids, and natural deep eutectic solvents (NADESs). Across compound classes, common patterns are identified, including the importance of external plant tissues as primary biological reservoirs, as well as a methodological convergence in extraction processes despite the wide chemical diversity of the molecules. Shared challenges related to compound stability, scalability, and process efficiency are also discussed. The results demonstrate that agro-industrial by-products should be understood as complex, integrated matrices rather than isolated sources of individual compounds, thereby supporting the development of unified biorefinery schemes. Unlike previous reviews focused on individual compound classes, this review integrates multiple classes of bioactive compounds, green extraction technologies, analytical characterization strategies, and industrial valorization approaches within a circular biorefinery framework. In conclusion, this review helps bridge the current fragmented understanding of waste valorization and highlights key opportunities for the sustainable development of high-value-added functional ingredients within the framework of the circular economy.

PMID:42450523 | DOI:10.3390/foods15132406

Molecules. 2026 Jul 1;31(13):2318. doi: 10.3390/molecules31132318.

ABSTRACT

This study investigated the rheological, structural, barrier, mechanical, optical, and thermal properties of composite edible films based on citrus pectin and vegetable purées derived from broccoli, cauliflower, pumpkin, carrot, and their blends. Film-forming formulations were characterized in terms of rheological behavior, thickness, microstructure, gas and water vapor permeability, optical and mechanical properties, water contact angle, and thermal stability. The incorporation of vegetable purées significantly modified the properties of the pectin-based matrices. All film-forming solutions exhibited non-Newtonian shear-thinning behavior, with flow behavior index values below unity. The addition of vegetable purées markedly increased viscosity and flow resistance, indicating the formation of more structured systems with stronger intermolecular interactions. Apparent viscosity increased from 0.19 Pa·s in the control sample to 1.41 Pa·s and 1.19 Pa·s in the broccoli (B) and broccoli-cauliflower (B-CF) formulations, respectively, while the consistency coefficient increased from 0.29 to 51.38 Pa·sⁿ. Composite films exhibited lower water contents (0.090-0.114 gH₂O·g_d.m.^-1) than the control film (0.179 gH₂O·g_d.m.^-1) and were thicker (170-282 μm) than the pure pectin film (125 μm). Barrier analysis revealed a reduction in water vapor permeability from 18.99·10^-10 to 10.74-14.69·10^-10 g·m^-1·s^-1·Pa^-1 and a decrease in carbon dioxide permeability from 21.95 to 10.47-17.91 GRT. The carrot-containing film exhibited the highest tensile strength (62.17 MPa), whereas the pumpkin-carrot film demonstrated the most favorable combination of barrier and mechanical properties, including the lowest oxygen permeability (6.95 GRT), low water vapor permeability (10.74·10^-10 g·m^-1·s^-1·Pa^-1), and high tensile strength (51.02 MPa). Thermogravimetric analysis revealed similar three-stage degradation profiles for all samples, while vegetable incorporation modified moisture release and increased residual mass. The obtained results confirmed the research hypothesis that vegetable-processing by-products can serve as valuable structure-forming components of pectin-based composite films and that interactions between vegetable-derived biopolymers and citrus pectin improve the mechanical, barrier, and functional properties of the resulting materials. Among the tested formulations, the pumpkin-carrot film demonstrated the greatest potential for further development as a biodegradable packaging material. The utilization of vegetable by-products in pectin-based films represents a sustainable approach supporting circular economy principles and the development of environmentally friendly packaging systems.

PMID:42451685 | DOI:10.3390/molecules31132318

Molecules. 2026 Jun 26;31(13):2253. doi: 10.3390/molecules31132253.

ABSTRACT

Agro-industrial by-products represent a sustainable and underutilized source of bioactive compounds with potential applications in human health. Among them, papaya (Carica papaya L.) peel, typically discarded during industrial processing, constitutes a promising and underexploited matrix for carotenoid recovery and valorization. In this study, different extraction strategies were evaluated and compared to identify the most efficient approach for carotenoid recovery. Total carotenoid contents of 7.13 ± 0.32, 5.35 ± 0.24, and 4.44 ± 0.38 µg β-carotene/100 g dry weight (DW) were obtained, respectively. The conventional extraction was further optimized using response surface methodology (RSM) to maximize carotenoid recovery and antioxidant activity. The extracts obtained under the optimized conditions were characterized by spectrophotometric analysis, HPLC-DAD, and in vitro antioxidant assays (DPPH and ORAC-FL), exhibiting antioxidant capacities of 528.4 ± 43.3 µmol TE/100 g DW and 5.0 ± 0.5 mmol TE/100 g DW, respectively. The carotenoid profile revealed lutein as the predominant compound (1414.28 µg/100 g fresh weight (FW)), followed by violaxanthin (629.55 µg/100 g FW), zeaxanthin (624.58 µg/100 g FW), β-cryptoxanthin (531.23 µg/100 g FW), and β-carotene (278.82 µg/100 g FW), while lycopene was not detected. The predominance of xanthophylls, particularly lutein, highlights the potential of papaya peel as a source of carotenoids that have been associated with visual health in previous studies, supported by its significant antioxidant activity. Overall, papaya peel is confirmed as a valuable and sustainable source of carotenoids, particularly xanthophylls associated with visual health, supporting its potential use in the development of functional ingredients. These findings contribute to circular economy strategies and support the sustainable production of bioactive compounds with potential applications in functional food and nutraceutical formulations.

PMID:42451622 | DOI:10.3390/molecules31132253

Materials (Basel). 2026 Jun 23;19(13):2686. doi: 10.3390/ma19132686.

ABSTRACT

This study (Part B) examines the potential utilization of municipal solid waste (MSW) ash, produced in a semi-industrial incinerator in Israel, as a partial substitute for cement and natural sand in industrial concrete mixtures. The ash was produced at the temperature range 600-850 °C, and the ash was characterized using XRD and SEM to determine its mineralogical composition and morphology. The results indicate that ash composition is dominated by calcium-rich phases, with hatrurite (Ca₃SiO₅) representing approximately 51-66 wt.% of the identified crystalline phases, along with calcite, MgO, and silica phases. The ash consists of irregular, porous particles with a broad distribution. Concrete performance was evaluated in both fresh and hardened states. In terms of fresh concrete properties, it is observed that concrete containing ash showed improved workability, better workability retention, and better concrete density compared to concrete without ash. In terms of hardened concrete properties, the use of MSW ash as a partial sand replacement preserved the mechanical performance of the concrete, with compressive strength remaining within approximately 2% of the reference mixture. These findings suggest that semi-industrially produced MSW ash is more suitable as a fine aggregate replacement than as a supplementary cementitious material and represents a promising route for reducing landfill disposal and promoting circular economy practices in the construction industry.

PMID:42451769 | DOI:10.3390/ma19132686

Molecules. 2026 Jul 6;31(13):2374. doi: 10.3390/molecules31132374.

ABSTRACT

The persistence of refractory organic pollutants (e.g., antibiotics) in aquatic environments necessitates efficient and sustainable remediation strategies. In this study, a circular economy approach was adopted to convert iron sludge into a value-added carbon residue (CR) composite via one-step co-pyrolysis. The resulting material was designed as dual-functional, enabling synergistic pollutant removal through adsorption and catalytic oxidation. Experimental results demonstrated that the CR composite effectively adsorbed and degraded organic pollutants. The primary adsorption sites were attributed to surface functional groups, porous structure, and electrostatic interactions. Meanwhile, iron species, surface functional groups, and persistent free radicals facilitated the generation of singlet oxygen (¹O₂) and hydroxyl radicals (·OH), which in turn promoted pollutant degradation. The CR/PDS system exhibited excellent performance in real wastewater remediation, which was attributed to the high interference resistance of ¹O₂. Furthermore, the application of CR did not pose any significant environmental risk in aqueous solutions. Taken together, these findings present a novel material for pollutant removal and provide a cost-effective strategy for the valorization of waste iron sludge.

PMID:42451741 | DOI:10.3390/molecules31132374

Materials (Basel). 2026 Jul 2;19(13):2808. doi: 10.3390/ma19132808.

ABSTRACT

Battery housings are critical structural and safety components in electric vehicles, fulfilling multiple functions related to mechanical protection, crashworthiness, thermal management, fire resistance, electromagnetic shielding, and integration of battery modules into the vehicle body. While metallic housings, particularly aluminum and steel, remain dominant in industrial applications, increasing attention is being given to composite materials as lightweight alternatives capable of improving energy efficiency and extending driving range. However, the growing use of composites in battery enclosures raises important questions regarding recyclability, end-of-life management, and compatibility with circular economy principles. This review critically examines the current state of the art in composite materials used for electric vehicle battery housings, with particular emphasis on glass- and carbon-fiber-reinforced thermoplastics, thermoset composites, sandwich structures, and hybrid multi-material systems. The paper discusses the functional requirements imposed on battery housings and analyzes how these requirements influence material selection and design strategies. Particular attention is devoted to recycling pathways applicable to composite battery enclosures, including mechanical recycling, thermal treatment, chemical recycling, and reuse-oriented approaches, as well as to the limitations associated with mixed-material assemblies, adhesives, coatings, and integrated functions. The review also addresses circular design strategies for battery housings, including design for disassembly, material traceability, modularity, and the incorporation of recycled polymers and secondary reinforcements into new housing systems. Current research gaps are identified in the integration of structural performance, fire safety, manufacturability, and recyclability within a single design framework. The analysis shows that thermoplastic composites currently offer the most promising route toward circular battery enclosures, while thermoset-based systems still face significant challenges in high-value recycling. The paper concludes by outlining future research directions required for the development of lightweight, safe and recyclable composite battery housings aligned with sustainable mobility and circular economy goals.

PMID:42451888 | DOI:10.3390/ma19132808

Materials (Basel). 2026 Jun 26;19(13):2743. doi: 10.3390/ma19132743.

ABSTRACT

Biomass-derived activated carbons (ACs) are promising sustainable adsorbents for water polishing; however, their performance in real aqueous matrices cannot always be predicted from BET surface area alone. In this study, chemically activated biomass-derived carbonaceous adsorbents were prepared from Cocoa Pod Husk (CPH), Watermelon Peel (WP), and Pineapple Crown (PC) and evaluated for Chemical Oxygen Demand (COD) removal from real eutrophic lagoon water. The materials were characterized by N₂ adsorption-desorption analysis, including BET surface area and BJH pore-size assessment, XRD, Raman spectroscopy, FTIR, UV-Vis diffuse reflectance spectroscopy, and pH_PZC analysis. Although all adsorbents exhibited low N₂-BET surface areas, adsorption performance was governed by apparent functional pore accessibility inferred from adsorption behavior, pore size distribution, surface chemistry, structural disorder, electronic delocalization, and surface charge. Among the acid-activated samples, ACPCSA5 showed a narrow average pore size of 1.720 nm and achieved near-complete COD removal. Its superior performance was associated with oxygen-containing functional groups, partially developed sp² carbon domains, lower optical band gap, BJH-derived pore architecture, and favorable surface charge at lagoon pH. The Microbial Regrowth Potential Index (MRPI) was introduced only as a conservative COD-based proxy, not as a validated biological indicator. Overall, this work demonstrates that adsorption in real-water matrices depends on accessible pore architecture and multifunctional surface chemistry rather than BET surface area alone.

PMID:42451824 | DOI:10.3390/ma19132743

Polymers (Basel). 2026 Jun 29;18(13):1615. doi: 10.3390/polym18131615.

ABSTRACT

The increasing demand for sustainable materials has intensified efforts to enhance the performance of recycled polymers for engineering applications. This study investigates the effect of nanoclay reinforcement on the mechanical properties of recycled high-density polyethylene (rHDPE). Nanoclay was incorporated into rHDPE at varying loadings through melt blending, and the resulting composites were evaluated in terms of tensile, flexural, impact, and hardness properties. The tensile strength and tensile modulus improved significantly with increasing nanoclay content, reaching maximum values of 31.27 MPa and 2.39 GPa, respectively, at 1.5 wt% nanoclay, corresponding to increases of 23.11% and 47.53% relative to unreinforced rHDPE. Similarly, the flexural strength and flexural modulus attained peak values of 25.88 MPa and 1105.08 MPa at 1.5 wt% nanoclay, representing improvements of 12.57% and 15.49%, respectively. Impact strength exhibited a different trend, achieving a maximum value of 73.58 kJ/m² at 0.5 wt% nanoclay before decreasing at higher loadings, indicating a transition towards more brittle behaviour. Hardness increased progressively with nanoclay addition and reached a maximum value of 68.06 Shore D at 1.5 wt%, exceeding both unreinforced rHDPE and virgin HDPE. The overall results demonstrate that nanoclay effectively compensates for the mechanical degradation associated with recycling by enhancing stiffness, strength, and surface hardness. Among the investigated formulations, 1.5 wt% nanoclay provided the optimum balance of mechanical performance, while higher loadings led to reduced reinforcement efficiency due to particle agglomeration. These findings highlight the potential of nanoclay-reinforced rHDPE as a sustainable, high-performance material for applications in packaging, construction, and automotive components, thereby supporting circular economy initiatives and resource-efficient material development.

PMID:42452072 | DOI:10.3390/polym18131615

Waste Manag. 2026 Jul 15;224:115729. doi: 10.1016/j.wasman.2026.115729. Online ahead of print.

ABSTRACT

Circular economy practices have elevated the role of reverse logistics in resource-intensive industries, where the recovery of high-value materials such as scrap steel is central to resource efficiency and environmental performance. This study develops an integrated multi-criteria framework addressing three questions typically treated in isolation: which reverse logistics strategy is most appropriate, which barriers shape its implementation, and which actions should be prioritised. The framework combines the Best-Worst Method (BWM) for criterion weighting, THOR II for ranking alternatives, the Decision-Making Trial and Evaluation Laboratory (DEMATEL) for distinguishing driving from dependent barriers, and Quality Function Deployment (QFD) for translating the diagnosis into prioritised solutions. The empirical application draws on five senior practitioners in the Turkish automotive industry, supported by two academic consultants during criteria validation; the same panel contributed to all four quantitative stages. THOR II is implemented with criterion-specific indifference, preference, and discordance thresholds derived from the empirical dispersion of each criterion, departing from the uniform-threshold practice shown to yield non-robust rankings. Economic and regulatory criteria carry the highest priorities, and in-house operation emerges as the leading strategy across all dominance scenarios, with outsourcing and the digital lean model as complements and public-private partnership ranking last. The informal scrap economy, the absence of a clear regulatory framework, and gaps in technology, incentives, and operational knowledge are the most influential driving barriers; prioritised actions converge on strategic embedding, regulatory clarity, and digital monitoring. The contribution is the demonstration that strategy desirability in emerging manufacturing economies cannot be separated from implementation feasibility.

PMID:42456597 | DOI:10.1016/j.wasman.2026.115729

Sci Total Environ. 2026 Jul 15;1047:182041. doi: 10.1016/j.scitotenv.2026.182041. Online ahead of print.

ABSTRACT

Securing sustainable phosphorus (P) resources from municipal sewage sludge is critical for circular nutrient management. This study investigates the effects of hydrothermal carbonization (HTC, 180 °C) and pyrolysis (450 °C and 600 °C) on two different sewage sludges: Stabilized Sewage Sludge (SSS) derived from an extended aeration activated sludge (EAAS) system, and Sludge Cake (SC) obtained from an anaerobic-anoxic-oxic (A/A/O) treatment process. Feedstock origin strongly governed phosphorus speciation, transformation pathways, and char properties during thermochemical processing. The two raw sludges were influenced by their original treatment, with SSS showing higher total phosphorus (TP = 39.04 mg g^-1) but a lower Ca/P molar ratio (0.20) compared with SC (TP = 26.10 mg g^-1, Ca/P = 0.50), indicating distinct P partitioning between mineral and organic fractions. Hydrochars (SH from SSS, CH from SC) showed moderate total P concentrations (TP) and retained some organic P (OP), whereas pyrolysis produced biochars with higher TP: 59.7 mg g^-1 in SB600 (SSS) and 46.0 mg g^-1 in CB600 (SC). OP decreased significantly from 6.38 mg g^-1 (SSS) and 8.15 mg g^-1 (SC) to below 2.5 mg g^-1, while inorganic P (IP) became dominant. In SSS biochars, apatite phosphorus (AP) was the main fraction, while in SC biochars, non-apatite inorganic P (NAIP) remained significant. These contrasting behaviors are attributed to feedstock-dependent mineral compositions, where Fe- and Al-associated fractions in SSS promoted conversion of NAIP into AP, whereas the higher initial Ca content in SC favored NAIP retention. Solid-state ³¹P NMR confirmed that orthophosphate (Ortho-P) is the main P species, highlighting its bioavailability and thermal stability. Pyrolysis increased carbonization, decreased H/C and O/C ratios (down to 0.44 and 0.33 at 600 °C), and generated highly porous, thermally stable chars. Overall, these results demonstrate that both sludge type and thermochemical pathway critically influence char properties and phosphorus forms.

PMID:42456625 | DOI:10.1016/j.scitotenv.2026.182041

Sci Rep. 2026 Jul 15. doi: 10.1038/s41598-026-58946-5. Online ahead of print.

ABSTRACT

Hazardous municipal solid waste incineration (MSWI) fly ash poses a global environmental challenge, with millions of tons annually ending up in landfills and risking heavy metal contamination of stormwater. Herein, for the first time in unwashed, high‑chlorine MSWI fly ash, we demonstrate a metal‑selective dual stabilization mechanism: lead (Pb) is chemically immobilized via covalent Pb-O-Si/Al bonding (XPS shift: - 0.6 eV), while cadmium and zinc are physically encapsulated. This mechanism enables a foamed geopolymer filter with four synergistic functions: (i) high Pb²⁺ adsorption capacity (200.6 mg·g⁻¹ at pH 6.0), (ii) steady water flux (0.082 mL·cm⁻²·s⁻¹) under continuous flow, (iii) low thermal conductivity (0.092 W·m⁻¹·K⁻¹), and (iv) intrinsic immobilization of the fly ash's own heavy metals. The filter maintained effluent Pb concentrations as low as 0.003 mg·L⁻¹ over five filtration cycles, well below national drinking water thresholds. This waste‑to‑value strategy provides a robust framework for upcycling hazardous byproducts into high‑performance environmental materials, advancing circular economy and sustainable water management.

PMID:42457750 | DOI:10.1038/s41598-026-58946-5

BMC Chem. 2026 Jul 14. doi: 10.1186/s13065-026-01880-4. Online ahead of print.

ABSTRACT

Citrus processing generates large amounts of by-products-mainly peels, pomace, and seeds-that are abundant in valuable bioactive compounds such as polyphenols, carotenoids, essential oils, pectin, and vitamin C. Efficient recovery of these compounds not only supports the production of functional ingredients but also aligns with circular economy and zero-waste objectives. Traditional extraction methods, including maceration, Soxhlet extraction, hydrodistillation, and solvent extraction, remain widely used but often require long processing times, consume significant energy and solvents, and can degrade heat-sensitive molecules. In recent years, greener and more innovative technologies-such as ultrasound-assisted, microwave-assisted, enzyme-assisted, supercritical fluid, pressurized liquid, pulsed electric fields, and deep eutectic solvent extractions-have emerged as sustainable alternatives, achieving higher yields and better compound stability with lower environmental impact. This review provides a critical comparison of conventional and emerging extraction methods, evaluating their efficiency, selectivity, scalability, and environmental performance. It also explores how these techniques influence the bioavailability and bioaccessibility of extracted compounds. Furthermore, potential applications of citrus by-product extracts in the food, nutraceutical, cosmetic, and agricultural sectors are discussed. Finally, the review addresses key technological, economic, and regulatory challenges related to industrial implementation and highlights future opportunities for integrating these extraction strategies into circular bioeconomy models.

PMID:42449430 | DOI:10.1186/s13065-026-01880-4

J Hazard Mater. 2026 Jul 13;515:142989. doi: 10.1016/j.jhazmat.2026.142989. Online ahead of print.

ABSTRACT

Tyre-related chemicals are emerging environmental pollutants. They can reach the aquatic environment via sustainable drainage systems (e.g., retention ponds). However, little is known about tyre chemicals in these engineered environments which themselves are important ecosystems. A key challenge of monitoring tyre chemicals is their changeable concentrations caused by road runoff. Therefore, it was proposed to establish a longer-term monitoring approach (e.g., ≥ 7 days) to complement low frequency grab sampling for improved fate and exposure assessments. A hydrophilic-lipophilic balance-Chemcatcher passive sampler configuration was assessed for uptake of 11 tyre-related chemicals including 1,3-diphenylguanidine, hexamethoxymethylmelamine (HMMM), and N-(1,3-dimethylbutyl)-N'-phenyl-p-phenylenediamine-quinone (6PPD-quinone). Ex-situ 14-day uptake calibrations showed linear uptake (r² values ≥ 0.9) in pond water with sampling uptake rates (R_S) in the range 0.0073 - 0.054 L/d. Both water temperature and flow velocity had a significant effect (p-value < 0.05) on R_S value for some chemicals. Subsequent in-situ monitoring revealed little reduction in tyre chemical concentrations through two retention pond systems. Nevertheless, 7-day and 14-day time weighted average concentrations were below the provisional predicted no effect concentration (PNEC) for most chemicals. However, all samples exceeded the current PNEC for HMMM (1.7 × 10^-2 µg/L) and by ≥ 20 times for some samples suggesting need for 'upstream' or within pond intervention. Non-targeted analysis tentatively identified a further 20 potential chemicals of interest in Chemcatcher extracts including vulcanisation accelerators, plasticisers and transformation products. Overall, the proposed Chemcatcher passive sampler can complement grab sampling to better monitor tyre-related chemicals in surface waters for their improved management.

PMID:42456583 | DOI:10.1016/j.jhazmat.2026.142989