Clean Technol., Volume 8, Issue 3 (June 2026) – 28 articles

In this work, ZnO nanoparticles were synthesized via a plant-mediated green route using Prosopis tamaulipana extract as a reducing and stabilizing agent and subsequently modified with silver to obtain Ag-modified ZnO powders. Structural and morphological characterization techniques confirmed the formation of nanocrystalline ZnO with a hexagonal wurtzite structure, submicrometric agglomerates composed of nanosized primary particles and a high degree of phase purity, indicating the effectiveness of the synthesis approach. The photocatalytic performance of the Ag-modified ZnO materials was evaluated under natural solar irradiation using methylene blue as a model organic contaminant in aqueous solution. Visual observations, together with absorbance, temperature and electrical conductivity measurements, demonstrated an effective and progressive degradation of the dye over a 5 h irradiation period. The observed increase in electrical conductivity under illumination was associated with enhanced charge carrier generation and improved separation efficiency, as well as the formation of reactive oxygen species, promoted by the presence of Ag as an electron sink. These results confirm that green-synthesized Ag-modified ZnO nanoparticles exhibit enhanced photocatalytic activity and are promising multifunctional materials for sustainable water sanitation applications. Full article

This study aims to develop sustainable conductive nanocomposites based on poly(lactic acid) (PLA)/poly(ε-caprolactone) (PCL) blends reinforced with multi-walled carbon nanotubes (MWCNT) and graphene nanoplatelets (G), focusing on their multifunctional performance. The novelty lies in the production of hybrid nanocomposites based on PLA/PCL blends with MWCNT/G using conventional industrial processing techniques, enabling the development of eco-friendly nanocomposites with tailored electrical, mechanical, and electromagnetic properties. The nanocomposites were prepared by twin-screw extrusion followed by injection molding. Rheological, scanning electron microscopy (SEM), mechanical, thermal, thermomechanical, electrical conductivity, and electromagnetic shielding properties were systematically evaluated. From a rheological perspective, the PLA/PCL/MWCNT and PLA/PCL/MWCNT/G nanocomposites exhibited a plateau at low frequencies, associated with the formation of a percolated network. This was confirmed by the significant increase in electrical conductivity and electromagnetic shielding response. The morphology observed by SEM showed a refinement of the PCL phase in the PLA matrix with the incorporation of MWCNT. The PLA/PCL/MWCNT/G (4/2 parts per hundred resin, phr) nanocomposite showed a 309% increase in impact strength compared to neat PLA, while maintaining the heat deflection temperature (HDT). The elastic modulus exceeded 2300 MPa and accelerated the crystallization process by more than 15 °C compared to PLA, which makes it important to reduce injection molding time. Additionally, it exhibited the highest electrical conductivity level, around 6.79 × 10⁻⁵ S/cm, which resulted in improved electromagnetic shielding performance in the 8.2–18 GHz range, highlighting the synergistic effect between 1D and 2D fillers. The developed PLA/PCL/MWCNT and PLA/PCL/MWCNT/G nanocomposites demonstrate potential for antistatic applications, combining sustainability with multifunctional performance and industrial scalability. Full article

This study investigates how the hydrogen supply chain should be designed under alternative carbon tax scenarios to decarbonize heavy-duty freight transportation. A bi-objective, multi-period optimization model is developed to minimize the total daily system cost while constraining CO₂ emissions using the Augmented ε-constraint approach, thereby revealing the trade-off between economic and environmental objectives. The model was applied to Türkiye’s heavy-duty transportation sector and solved under zero, moderate, and aggressive carbon tax scenarios. The results show that the levelized cost of hydrogen (LCOH) ranges from 2.06 to 14.06 $/kg H₂. High carbon pricing increases the LCOH by 29.06% in hybrid designs, while raising the renewable energy share from 2.04% to 46.97% in centralized supply chains. Sensitivity analysis reveals that a ±20% variation in electrolyzer-based production costs does not alter the network topology but shifts the LCOH between 13.10 and 15.02 $/kg H₂ in emission-focused solutions. The findings indicate that in renewable-energy-based decentralized structures, higher carbon tax policies primarily increase the LCOH. Still, the overall technology mix and network topology remain largely unchanged compared to the no-tax case. However, in centralized supply chains, carbon pricing affects both the energy sources and selected technologies. By integrating Türkiye’s 2030–2053 policy milestones into a multi-period framework, this study distinguishes itself by providing a comprehensive, multi-period planning framework tailored to the economic and logistical realities of developing countries. Unlike existing models, our approach quantifies how evolving carbon tax trajectories decisively drive infrastructure investment by analyzing the direct impact of different tax levels on the operational and strategic decisions of heavy-duty transport. This research represents the first joint assessment of carbon tax policy instruments and the evolution of long-term hydrogen supply chains, offering a decision-making framework for policy-driven energy transitions in similar emerging economies. Full article

Ammonia, as a carbonless carrier of energy, presents considerable potential for hydrogen storage and production, as well as for power generation, thanks to its high energy density and relatively easy transportability. However, the practical adoption of ammonia in combustion systems faces major stability challenges—chiefly its low reactivity, slow laminar burning velocity, narrow flammability envelope, and high ignition temperature. These attributes increase the risks of flame instability, misfire, and incomplete combustion, which, in turn, can elevate levels of unburned ammonia and greenhouse gas emissions such as NOx—posing significant health and climate concerns. Stable ammonia combustion demands optimization of several interrelated factors: the air–fuel equivalence ratio, flame temperature, flow regime, and combustor design are critical for maintaining reliable operation. Particularly pivotal is the control of the air–fuel equivalence ratio; excessively lean conditions can trigger flameout. Modern systems utilize real-time monitoring of flame and exhaust properties to diagnose and prevent instabilities. Advanced combustion strategies, such as transitioning to diffusion or flameless (MILD) regimes, substantially expand the stable operating window, especially under lean conditions. Overall, sustaining stable ammonia combustion is essential for maximizing efficiency and emission control, and integrating aftertreatment (deNOx) technologies is crucial for sustainable, clean-energy implementation. Full article

Soil cadmium (Cd) pollution has emerged as one of the key environmental issues threatening the safety of agricultural products worldwide, yet clean and low-cost intervention strategies that reduce Cd accumulation in edible crops without disrupting agricultural production remain scarce. Grafting onto tolerant rootstocks represents an emerging clean agronomic technology that achieves in situ Cd risk reduction within a single growing season. However, the molecular mechanisms by which rootstocks regulate scion phenotypes remain poorly understood. MicroRNAs (miRNAs) act as critical long-distance signals in plants, yet their roles in rootstock-mediated growth promotion and Cd reduction remain largely unclear. In this study, we used Solanum torvum as rootstock and purple eggplant (Solanum melongena) as scion to investigate growth, fruit quality, Cd accumulation, and miRNA-mediated regulatory mechanisms. Grafting significantly increased plant height (by 18%), stem diameter (by 12%), and yield without obvious effects on fruit quality. Under Cd stress, the Cd content in grafted eggplant fruits was reduced by 76%, whereas leaf potassium (K), calcium (Ca), and magnesium (Mg) contents were elevated by 21%, 17%, and 10%, respectively. High-throughput sequencing and quantitative real-time polymerase chain reaction identified five key differentially expressed miRNAs, including miR164a and miR166b, four of which were related to Cd stress. Gene Ontology (GO) enrichment analyzes that their target genes were mainly involved in hormone signal transduction and ion transport. Further validation suggested that grafting improved growth and reduced Cd accumulation by regulating genes of the NAC, SPL, and HD-ZIP III families. These results suggested that suitable rootstocks can enhance crop productivity and reduce toxic metal accumulation in edible parts through miRNA-mediated regulation. Full article

The rapid expansion of the hydrogen economy has intensified the need for accessible production technologies. This study presents a comparative assessment of two next-generation hydrogen production systems showcased at the Hydrogen Expo Hamburg 2025: the containerised HyPro electrolyser and the modular Enapter EL 4.1. The analysis focuses on their technical specifications, operational philosophies, and indicative costs. Data were gathered through technical consultations with exhibitors and catalogue analyses. The evaluation highlights key differences in system architecture, production capacity, and installation requirements within academic research environments. The results demonstrate how suitability depends on the intended scale of application, contrasting a laboratory-ready modular approach with an industrial-oriented turnkey configuration. This study provides practical insights to support universities and research institutions in selecting hydrogen production equipment that aligns with their specific infrastructural and budgetary conditions. Full article

The adsorption of H₂S impurity in the gas flow on carbon adsorbents produced from coconut shells and sugarcane bagasse was studied. The runs were carried out in pulse mode. An original chromatographic method for determining the degree of H₂S absorption on carbon adsorbents has been developed, which makes it possible to determine the amount of absorbed H₂S in air and water environments. The results obtained show that the successive treatment of carbon adsorbents first with a solution of a strong oxidizer (HNO₃, KMnO₄) and then, after washing, with an alkali solution (KOH) leads to a sharp increase in the amount of H₂S adsorbed. The efficiency of H₂S absorption on the obtained adsorbent reaches 85.5%, which corresponds to 27.7 mg/g H₂S and is comparable to the results obtained on commercial coconut carbon (CAU). The data allow one to conclude that the rise in the H₂S adsorption on the carbon sorbents studied can be due to the increase in the micropores’ volume in the activated carbon, as well as the formation of surface functional groups containing an alkali metal (i.e., C-OK, C-COOK) that promotes irreversible chemisorption of H₂S impurity on the carbon adsorbent. The absorption of H₂S occurs through the chemisorption mechanism, which is confirmed by IR spectroscopy data. Full article

This study proposes an integrated and more circular management approach, grounded in the principles of sustainable and green chemical processes, for the food waste leachates management, combining the assessment of biomethane production potential via anaerobic digestion with the evaluation of value-added compound recovery through extraction processes. The food waste leachates were characterized, while total carotenoid profile and total phenolic content were quantified using liquid–liquid extraction with mixed organic solvents. An HS-SPME coupled with GC–MS was employed to identify volatile organic compounds present in the leachates. Prior to the extraction procedure, D-limonene exhibited the highest abundance among identified volatiles. Crucially, the subsequent solvent extraction is highly likely to have effectively removed this inhibitory terpene from the liquid matrix. Extracted leachates exhibited a total carotenoid content of 0.64 mg/100 g and a total phenolic content of 127.0 μg/g, acting as preliminary indicators of significant potential for recovery and utilization in pharmaceutical and cosmetic applications. Biomethane potential tests were conducted in laboratory-scale anaerobic bioreactors using both raw food waste leachate and extracted food waste leachate. Comparable biomethane yields were obtained for both substrates, with FWL yielding 442.5 NmL/g VS_added and FWL_extr yielding 452.2 NmL/g VS_added. These results demonstrate that the liquid–liquid extraction of value-added compounds does not adversely affect biomethane production from food waste leachates enabling the recovery of valuable by-products. Full article

Topics related to renewable and sustainable energy have been addressed by several scientific studies over the last few decades. Nonetheless, it is important to highlight what has already been done by the scientific community and what remains to be done in these fields to provide more insights for stakeholders, including policymakers, researchers, and economic operators. The literature survey showed that there are still gaps to be considered in the literature and novelties to be brought through different approaches, particularly those that take into account the several dimensions of these issues. From this perspective, this research aims to present the dimensions of renewable and sustainable energy explored in scientific documents, benchmarking past and future pathways in these domains. To achieve these objectives, a bibliometric analysis (focusing on scientific maturity) was carried out separately across different dimensions associated with this topic (this is one of the novelties of this study). Additionally, a targeted literature analysis based on bibliometric analysis was done, considering the most relevant documents. This research adopts a broad perspective in order to capture the context of energy transition, clean energy, and low-carbon development. The findings obtained show that the subject of renewable and sustainable energy has several topics and subtopics with different dynamics. Within these subtopics, it is worth mentioning the following: solar and wind energy are almost in the saturation phase (85.1% of potential development has already occurred); bioenergy, biomass, and hydroelectric power are at the beginning of the maturity phase (59.7% progress to saturation); tidal and wave energy are in the middle of the maturity phase (71.5% progress to saturation); green hydrogen and clean energy are in the saturation phase (99.0%); renewable energy and sustainable development goals are in the saturation phase (99.0%), and energy policy and technological innovation in renewable energy are in the middle of the maturity phase 68.0%). These results reflect the overlap between different topics rather than the individual scope of each field of research. Full article

Purified terephthalic acid (PTA) is an extremely important bulk organic raw material; it plays a central connecting role in the PX–PTA–polyester industry chain, while its significant carbon intensity remains poorly quantified. Through process-level life cycle assessment (LCA) based on in situ industrial data, this study establishes a comprehensive material-energy inventory for PTA production. The results show that the total greenhouse gas (GHG) emissions of the entire PTA process reached 1600.9 kg of CO₂ eq·t⁻¹, exceeding those of common primary chemicals, like aromatics, butadiene and styrene. The end process of the PTA unit (PU) dominates GHG emissions, reaching 365.6 kg CO₂ eq·t⁻¹, accounting for 22.3%, driven by extra xylene input, various catalyst consumption, auxiliary chemicals, and energy intensity. After allocating steam-related emissions from coal-fired power stations, the GHG emissions of the PU rise to 400.9 kg CO₂ eq·t⁻¹. Sensitivity analysis demonstrates that replacing conventional hydrogen with green hydrogen slashes hydrogen-related global warming potential (GWP) contribution by 61.5%. In addition, a 10% increase in electricity, coal, or steam elevates system GWP by 0.80%, 0.036% and 2.48%, respectively. The findings demonstrate that energy structure optimization and green hydrogen integration represent decisive levers for PTA decarbonization, providing data-driven insights for industrial transition under a carbon reduction policy framework. Full article

Given the large natural gas (NG) reserves of the Intermountain West (I-WEST) region in the USA, it can emerge as a leader in hydrogen (H₂) production. Currently, H₂ production via steam methane reforming (SMR) of NG releases carbon dioxide (CO₂) and the natural gas infrastructure has fugitive NG and H₂ losses during production, conversion and transportation. Integrated carbon capture and sequestration (CCS) is a promising approach for producing hydrogen and CO₂ from the SMR process for industrial uses including power, chemicals and fuels. However, the NG losses and regional water availability can be limiting factors for H₂ production. H₂ production assessments are often made at the global scale and neglect regional factors such as abundant gas and limited water in the I-WEST. We demonstrate that a regional SMR process unit sitting near NG wells offers opportunities to significantly reduce fugitive NG losses. We show that regional H₂ production by SMR has a lower emissions profile than widespread natural gas combustion in the I-WEST and reduces the H₂ production cost as well. Replacing the I-WEST transportation sector with H₂ fuel cell vehicles and using 100% H₂-powered electricity can provide substantial reductions in water consumption and fuel costs. This is better than blending H₂ with NG which is more expensive. The captured CO₂ can be effectively used for enhanced oil recovery in I-WEST. Finally, the potential of utilizing produced, brackish and treated impaired water sources is assessed to meet the water needs for H₂ production in the I-WEST. Full article

This study presents an experimental engine map investigation of waste swine oil biodiesel (WSO B100) in a single-cylinder, four-stroke variable compression ratio compression ignition engine, quantifying the coupled effects of compression ratio and load on brake thermal efficiency, brake-specific fuel consumption, torque, brake power, and regulated emissions of NOx, CO, HC, and CO₂. Compression ratios of 12, 14, 16, and 18 were evaluated at dynamometer loads of 25%, 50%, and 75% under steady-state operation. The study’s primary contribution is a structured compression ratio–load mapping framework that produces consistent performance emission response surfaces and, supported by statistical modeling and sensitivity analysis, resolves main and interaction effects to identify operating regions that balance efficiency and emissions. Methodological traceability is strengthened by attaching fuel energy and mass flow calculations to batch-specific fuel properties, including viscosity and density, and by using calorimetry-derived heating value in efficiency calculations. Increasing the compression ratio from 12 to 18 improved brake thermal efficiency by 3–10% at low load and reduced brake-specific fuel consumption, while NOx increased by 20–30% across the load range. Increasing load raised brake thermal efficiency from 29% at 25% load to 42% at 75% load and reduced brake-specific fuel consumption from 309 to 215 g/kWh; NOx peaked at 488 ppm at 75% load and compression ratio 18. CO and HC decreased with both load and compression ratio, reaching minima of 0.15% and 30 ppm, whereas CO₂ increased primarily with load. Relative to diesel, WSO biodiesel showed 8–12% higher brake-specific fuel consumption and 2–4% lower peak brake thermal efficiency, but achieved substantial CO and HC reductions. Generally, WSO biodiesel operates effectively across a wide compression ratio range with broadly comparable performance to diesel. However, increased NOx and reduced low-load efficiency indicate the need for targeted calibration or emission control. Full article

Compared with previous analytical models that mostly neglect air–lining coupled heat transfer, the proposed model innovatively introduces this mechanism and achieves a maximum error reduction of 0.5% against experimental data. The analytical solution of the model is obtained by using the Green’s function method. The reliability and accuracy of this model are confirmed through comparisons with existing experimental data. Research indicates that adjusting the tunnel air temperature improves the ground heat exchanger’s heat exchange efficiency more significantly than modifying the thermal conductivity of the lining. In the tested range, as the flow velocity increases, its influence on the heat transfer effect gradually weakens. The simulation results indicate that under summer operating conditions, only approximately 5–8% of the heat transferred by the ground heat exchanger is dissipated to the tunnel air-side environment, while the vast majority (92–95%) is conducted to the surrounding rock. Full article

Accurate and rapid determination of moisture content in waste sludge is essential for optimizing dewatering processes, reducing disposal costs, and minimizing environmental impact. This study investigates the use of Fourier Transform Near-Infrared (FT-NIR) spectroscopy combined with Partial Least Squares Regression (PLS-R) for predicting the moisture content of dewatered sludge. A total of 96 sludge samples, with dry matter contents ranging from 12.4% to 24.6%, were collected from two treatment plants. FT-NIR spectra were acquired over the 800–2500 nm range, and chemometric models were developed to correlate spectral information with gravimetrically determined moisture content. The optimized PLS-R model demonstrated strong predictive performance, achieving a cross-validated coefficient of determination (R²_CV) of 0.87, a root mean square error of cross-validation (RMSECV) of 0.92%, and a residual predictive deviation (RPD) of 2.73. Independent test set validation confirmed the robustness of the model (R²_Test = 0.88, RMSEP = 0.88%, RPD = 2.92), supported by strong calibration results (R²_CT = 0.95, RMSEE = 0.60%, RPD = 4.46). Principal component analysis indicated that spectral variability observed in sludge samples was primarily associated with wastewater treatment plant (WWTP)-specific characteristics, reflecting moisture–organic matter interactions. These results demonstrate that FT-NIR spectroscopy is a promising tool for sludge moisture prediction. Full article

Domestic wastewater is a chemically complex and highly variable mixture of pollutants generated by everyday household activities, yet its contribution to environmental contamination is still frequently underestimated and only 56% of wastewater worldwide is being treated. This review provides a structured and quantitative assessment of major domestic wastewater pollutant groups, their principal exposure pathways, and current and emerging treatment technologies. Beyond a conventional narrative synthesis, the review derives per capita annual emission estimates from published data and uses these to compare pollutant groups by mass flow and environmental relevance. The analysis shows that high-volume household inputs, particularly sodium chloride from domestic water softening, toilet paper, personal-care products, detergents, and cleaning agents, can contribute substantially to overall pollutant loads, whereas lower-mass contaminants such as pharmaceuticals, antibiotics, PFAS, heavy metals, and microplastics remain critical because of their persistence, biological activity, and incomplete removal during treatment. The review further highlights that conventional wastewater treatment systems are often poorly equipped to remove many of these emerging contaminants effectively, especially under decentralised or only partially advanced treatment conditions. Advanced and hybrid technologies, including membrane bioreactors, nanofiltration, reverse osmosis, adsorption, photocatalysis, and electrochemical processes, offer clear potential, but their broader implementation remains constrained by cost, energy demand, fouling, and concentrate management. Overall, the added value of this review lies in linking mass-based pollutant prioritisation with treatment performance, thereby providing a more systematic basis for identifying dominant household emission pathways and for guiding targeted mitigation and technology selection in future wastewater management. Full article

Chile is widely regarded as a key global player in green hydrogen production due to its exceptional renewable energy potential, which enables low-carbon and competitive production costs. This article provides a comprehensive review of Chile’s green hydrogen sector, evaluating the transition from early strategic goals to the current phase of industrial scaling. It offers an integrated analysis of the regulatory framework, infrastructure deployment, and the techno-economic variables essential for integrating Chilean derivatives into global markets. The country has established a supportive framework through its National Green Hydrogen Strategy (NGHS), which sets out goals of 25 GW of installed electrolyzer capacity and USD 2.5 billion in annual exports by 2030. Despite these ambitious targets, actual deployment remains in the early stages, with only 3.9 GW currently in the implementation phase and a lack of fully operational industrial-scale facilities. Furthermore, initial NGHS projections suggested a levelized cost of hydrogen (LCOH) of USD 1.3–1.4/kg by 2030. However, current calculations point to a more complex reality of approximately USD 3.1/kg due to infrastructure bottlenecks and global supply chain pressures. While Chile’s renewable resources ensure low production-stage emissions, the absence of explicit regulatory carbon targets underscores the need for comprehensive life-cycle assessments encompassing manufacturing and global distribution. Overall, this review concludes that Chile should overcome persistent regulatory and logistical constraints to consolidate a robust and internationally competitive green hydrogen sector, aligned with its 2050 carbon neutrality objectives. Full article

The construction sector is a major consumer of raw materials and a significant source of greenhouse gas emissions, necessitating data-driven approaches to support circular economy implementation and sustainable project management. This study develops an integrated framework combining machine learning-based material stock prediction, carbon footprint assessment, and Environmental, Social, and Governance (ESG) performance evaluation for construction projects. A dataset of 128 residential buildings was compiled from official use-permit documentation. After dimensionality reduction using variance filtering and Spearman correlation analysis, 25 regression algorithms were evaluated to estimate quantities of concrete, reinforcement, and brick products. The K-Nearest Neighbor (KNN) Regressor achieved the best predictive performance, with mean absolute percentage errors of 10.64% for concrete, 10.23% for reinforcement, and 16.05% for brick products. Predicted material quantities were used to calculate CO₂ emissions across materialization, demolition, and disposal phases under linear and circular scenarios. The results indicate that circular economy implementation significantly reduces total emissions, particularly for concrete, with reductions of up to 97% under idealized full-substitution conditions, representing an upper-bound estimate. ESG assessment using the Delphi method identified environmental indicators as the most significant sustainability dimension. The proposed framework enables early-stage emission estimation and supports informed decision-making toward low-carbon and resource-efficient construction practices. Full article

Rapid global urbanization is driving a surge in solid waste generation, while conventional treatment systems face both environmental risks and operational uncertainty. Digital twins, which enable real-time mapping between physical assets and virtual spaces, offer a computable and verifiable route toward low-carbon, resource-efficient, and intelligent waste management when deeply integrated with the Internet of Things, big data, and artificial intelligence. This study develops a comprehensive review tracing the digital twins from static geometric mirroring to dynamic, cognitive co-symbiosis, and summarizes a multidimensional architecture spanning physical, virtual, data, service, and connectivity layers, together with coupling mechanisms involving IoT sensing, federated learning, multimodal big data, and large model agents. The study aims to provide a theoretical framework and methodological references for advancing digital twin-enabled solid waste valorization. Building on this framework, we examine recent progress in three representative application scenarios for solid waste treatment, and identify key technical bottlenecks, including heterogeneous data fusion, model generalization across facilities and contexts, and real-time computation under constrained resources. We highlight the need for standardization, uncertainty quantification, cybersecurity, and lifecycle evaluation to support reliable prediction, optimization, and decision-making in real operations. Finally, we discuss future directions such as edge intelligence and the integration of city-scale material and energy networks. Full article

Eggshell waste generated by the poultry processing industry represents a significant yet underutilized biogenic resource with substantial potential for sustainable agricultural and environmental applications. Globally, several million metric tons of eggshell residues are produced annually, consisting predominantly of calcium carbonate (CaCO₃) in the form of calcite, along with minor quantities of organic matrices and trace minerals. These physicochemical characteristics make eggshells a promising renewable alternative to conventional mineral sources for use as fertilizers, soil amendments, and biomaterials. Recent studies have shown that finely ground eggshell powder (ESP) is an effective liming material that can regulate soil chemical conditions and improve agronomic performance under acidic soil conditions. Furthermore, eggshell-derived materials have been incorporated into composting systems, biochar composites, and nanostructured fertilizers to enhance nutrient dynamics, immobilization of contaminants, and microbial activity. Advances in nanotechnology have facilitated the synthesis of nano-calcium carbonate (NCC) and nanohydroxyapatite (nHAP) fertilizers with improved nutrient supply and controlled-release properties. However, challenges associated with nanosafety evaluation, large-scale processing technologies, regulatory harmonization, and long-term field validation remain. Therefore, this review critically synthesizes the structural, biochemical, and physicochemical properties of eggshells and eggshell membranes, examines their applications in sustainable agriculture and environmental remediation, and identifies the key research priorities required to advance eggshell valorization within circular bioeconomy strategies. Full article

Propyl-paraben (PrP) is a common preservative found in cosmetics and pharmaceutical products. It is classified as a category 1 endocrine-disrupting compound, which highlights the importance of efficiently removing it from water during treatment processes. This study investigates the potential of using Leptolyngbya sp. dominated cyanobacterial biomass residues, in both their raw and hydrothermally treated (hydrochar) forms, for the removal of PrP from aqueous media. Batch and fixed-bed column experiments were carried out under varying conditions to assess adsorption kinetics and equilibrium behavior. Both raw biomass and hydrochar exhibited satisfactory PrP removal, achieving maximum adsorption capacities of 224.58 and 258.55 mg/g respectively, at 10 mg/L initial PrP concentration and 23.33 mg/L adsorbent dosage. Equilibrium data were best described by the Freundlich isotherm model, indicating a heterogeneous surface and multilayer adsorption. The kinetic analysis revealed that the adsorption behavior, for both adsorbents, was best described by the pseudo-second-order model, while the thermodynamic evaluation revealed negative ΔH° and ΔS° values, confirming an exothermic, physisorption-driven process. The adsorption mechanism was further investigated through surface characterization techniques, including Fourier Transform Infrared Spectroscopy, Scanning Electron Microscopy, N₂ physisorption, and zeta potential analysis. The findings demonstrate the potential of microalgal biomass as a low-cost, sustainable biosorbent, for emerging contaminants, reinforcing its role in advanced water treatment and circular economy strategies. Full article

Emerging compounds in water, ranging from dyes to pharmaceuticals, negatively impact living organisms and challenge the industries responsible for their release. These pollutants exhibit chemical persistence and resistance to conventional treatment processes. Adsorption is considered an effective and accessible approach, particularly when low-cost and renewable materials are employed. The Problem-Intervention-Comparison-Outcome (PICO) framework and Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) 2020 guidelines were followed. A structured search of Scopus was conducted to identify English-language original peer-reviewed articles published between 2016 and 2025 addressing the use of fruit waste (FW)-derived adsorbents for water decontamination. After independent screening, 528 studies were included. Risk of bias was assessed qualitatively. Due to substantial heterogeneity in materials, contaminants, and experimental designs, findings were synthesized narratively. FW-derived adsorbents were evaluated in terms of synthesis routes, physicochemical characteristics, adsorption mechanisms, kinetic and equilibrium behavior, process optimization and regeneration performance. Correlations were observed between surface functionalization, material properties and contaminant-specific removal efficiency, while limitations were noted for multi-component systems, regeneration stability, standardization and scale-up. By integrating material design with process-level considerations, this review outlines priorities for advancing FW valorization toward practical and sustainable water treatment applications. Full article

This study investigates the use of type A zeolite as a filtering material for the removal of toxic and carcinogenic compounds from cigarette smoke, which contains nicotine and other harmful substances produced by tobacco combustion. The aim is to evaluate the effectiveness of zeolite in reducing exposure to secondhand smoke, with particular attention to health and environmental impacts. The zeolite was characterized using SEM-EDS, XRD, DSC, and TGA to determine its morphology, chemical composition, crystalline structure, and thermal stability. An experimental setup was designed to simulate realistic smoking conditions and test filter efficiency based on the active mass. The system allowed identification of harmful substances trapped in the filter and those remaining in the air. Performance was assessed through gravimetric analysis and GC-MS, enabling identification of adsorbed and non-adsorbed compounds. Results demonstrate significant efficiency in selective removal of toxic components. Finally, filter performance was compared with carbon nanotubes, tested under the same experimental protocol. Full article

Maritime transport is energy-efficient but remains heavily dependent on fossil fuels. Renewable electricity-based ammonia (e-NH₃) has emerged as a promising alternative, particularly through small-scale, modular production. Assessing its economic viability is essential for future adoption, and techno-economic analysis offers a structured way to evaluate its feasibility. This study investigates the cost performance of a small-scale offshore e-NH₃ plant of 2.4 tons per day (tpd) at the Port of Santander, Spain, based on nitrogen obtained via membrane separation and hydrogen from electrolysis of pretreated seawater. The results are based on process simulation outcomes obtained using ASPEN v14, and the detailed cost breakdown is derived from modular costing methodologies applied to preliminary process designs and sensitivity analyses of the levelized cost of ammonia (LCOA) with respect to the main variables. A comparative review of LCOA values reported in the literature for offshore and onshore e-NH₃ plants is provided. An estimated CAPEX of 5.99 M EUR (equivalent to 0.53 M EUR/y), OPEX of 1.58 M EUR/y, and an LCOA of 2408 EUR/tNH₃ are obtained, with equipment investment and operating costs identified as the most influential parameters. The results highlight the need for supraregional techno-economic studies considering optimal offshore wind availability within a collaborative interregional framework. Full article

The valorization of agro-industrial by-products through sustainable extraction of bio-compounds is a key challenge within circular economy and clean-processing frameworks, as large volumes of tomato and artichoke residues are generated by the food industry. This study evaluated the impact of non-thermal technologies on the recovery of biocompounds from tomato peels and blanched artichoke bracts using single green solvents instead of solvent mixtures. Ultrasound-assisted extraction (sonication), high-pressure processing (pressurization), and dual processing (pressurization + sonication) were compared with conventional extraction. Ethanol was used for lycopene extraction, while water was employed for inulin-type fructan recovery. Lycopene, total phenolic content, antioxidant activity, and inulin-type fructans were quantified. Non-thermal treatments significantly influenced extraction yields (p < 0.05). The dual processing provided the highest lycopene and inulin-type fructan contents (1440.09 ± 0.71 µg/g DW and 5.17 ± 0.51 g/100 g DW, respectively) and enhanced antioxidant activity in tomato peels and blanched artichoke bracts (25.50 ± 0.20% and 66.11 ± 2.03%), and phenolic co-extraction (1783.2 ± 215.3 μg GAE/g DW and 27.68 ± 1.29 mg GAE/g DW) outperformed individual technologies and conventional extraction. Compared with the conventional process, dual processing improved the extraction yields of lycopene (20.60 ± 0.44%) and inulin (26.40 ± 13.95%). The findings prove that non-thermal processes, particularly when combined, intensify mass transfer and enable efficient extraction using green solvents, offering a sustainable strategy for recovering bioactive compounds from tomato and artichoke by-products. Full article

The continuous increase in atmospheric CO₂ concentration exacerbates global climate change, making carbon reduction an urgent global priority. Carbonic anhydrase (CA), a highly efficient biocatalyst that converts CO₂ into bicarbonate, demonstrates significant potential for carbon capture and resource utilization. However, the stability and catalytic efficiency of native CA in industrial environments are limited, particularly its poor thermal tolerance under flue gas conditions and its sensitivity to impurities, hindering its direct large-scale application. This review systematically summarizes recent advances in modifying microbial CA through protein engineering (e.g., directed evolution, rational design) and immobilization techniques, which have markedly enhanced its thermal stability, adaptability, and reusability. Among these, the integration of machine learning with high-throughput experimentation has emerged as a transformative strategy for CA engineering. Furthermore, we outline CA-driven pathways for CO₂ conversion into high-value chemicals and bioenergy. Finally, future prospects are discussed, including interdisciplinary integration, computational modeling coupled with experimental validation, and comprehensive life-cycle and techno-economic assessments, to facilitate the scaled application of engineered microbial CA in carbon neutrality pathways. Collectively, this review highlights the critical role of engineered CA in bridging biocatalysis with industrial carbon management, offering a viable and sustainable pathway toward carbon neutrality. Full article

The transition toward low-carbon and circular Municipal Solid Waste (MSW) systems requires integrated evaluation approaches that consider environmental performance, technological maturity, and governance capacity. This study presents a structured, systematic review of MSW disposal and treatment practices published between 2018 and 2026, following the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) 2020 guidelines. A total of 71 studies were included and analyzed. Due to heterogeneity in methodologies, system boundaries, and reported indicators, no formal meta-analysis was conducted. Instead, the review provides a comparative and qualitative synthesis of key environmental indicators and structural determinants. Results indicate a transition from open dumping toward engineered landfills and advanced treatment technologies, including waste-to-energy and biological processes. Open dumping is consistently associated with high greenhouse gas emissions and environmental risks, while engineered systems improve containment and enable partial resource recovery. The findings highlight that environmental performance is not determined solely by technology but by the interaction between infrastructure design, operational quality, governance capacity, and economic conditions. The proposed analytical framework supports context-sensitive waste management strategies aligned with circular economy principles and climate mitigation objectives. Full article

Polyunsaturated fatty acids, particularly γ-linolenic acid, are recognized for their therapeutic and nutritional properties. Zygomycetes, such as Cunninghamellaelegans, represent a promising microbial platform for sustainable gamma-linolenic acid (GLA) production as an alternative to conventional sources. Despite this potential, the immunomodulatory activity of metabolites from C. elegans has not been previously explored. In this study, C. elegans was cultivated on hydrolysates from discarded residues of Pleurotus spp. cultures (DRPC-HL), optimized to release assimilable compounds, promoting valorization of low-value biomass within a circular bioeconomy. Dry mycelial biomass, lipid-free biomass, and intracellular lipids from these cultures, alongside previously reported C. elegans cultures grown under nitrogen-excess (N-Xs) and nitrogen-limited (N-Lim) conditions, were tested on THP-1-derived macrophages, under lipopolysaccharide (LPS)-induced inflammatory conditions. Following in vitro gastrointestinal digestion, dry biomass and lipid-free dry biomass fractions upregulated the anti-inflammatory cytokine IL10 and downregulated IL1B and TNF, particularly from N-Xs and DRPC-HL cultures. Lipids mainly enhanced IL10 expression, especially when derived from N-Xs cultures. No changes were observed in upstream regulators (TLR2, TLR4, NFKB1, RELA), suggesting a feasible post-receptor immunomodulatory action. Overall, these findings highlight the dual value of fungal bioproducts derived from agro-industrial residues, combining sustainable bioprocessing with bioactive compound generation, supporting environmentally friendly microbial platforms for industrial applications. Full article

With the rapid growth of the medicinal cannabis sector, there is a growing concern regarding its environmental impact and sustainability. In recent years, life cycle assessment (LCA) studies on medicinal cannabis cultivation and processing have been conducted since 2021. However, there is a lack of comprehensive LCA studies that include all stages of medicinal cannabis cultivation and processing. In this systematic review, various LCA studies conducted from 2021 to 2025 using the ISO 14040/44 methodology are reviewed and discussed in terms of their goal and scope, life cycle inventory (LCI), life cycle impact assessment (LCIA), and result interpretation. Various environmental impact indicators are considered in this review, such as greenhouse gas emissions, energy demand, water usage, eutrophication, acidification, and resource depletion. All of these impact indicators point to a significant environmental impact of indoor cultivation in terms of greenhouse gas emissions, which vary from 2.3 × 10³ to 5.2 × 10³ kg CO₂ eq kg⁻¹ of dried cannabis product. Nevertheless, it is important to note that this is significantly influenced by regional electricity sources. Low-carbon-based electricity sources, especially hydro-based sources, can reduce emissions to a significant level. Cultivation outdoors presents significantly lower emissions of (60–110 kg CO₂ eq kg⁻¹), but fertilizers and substrates used in cultivation contribute significantly to emissions. Also, outdoor plants use 22.7 L plant⁻¹ d⁻¹ water at peak growth, while indoor plants use 9–11 L plant⁻¹ d⁻¹ water. Improvements in the life cycle of cannabis cultivation can be achieved through renewable energy use, water and fertilizers, substrate use and reuse, and inventories for post-harvesting activities like drying and extraction. Botanical parameters including genotype, planting density, and harvesting frequency are identified as significant but under-characterized determinants of LCA outcomes. Ethical and legal barriers are shown to be structural drivers of the LCA data gap. A SWOT analysis contextualizes the opportunities and constraints of the sector. Future research should focus on cradle-to-grave LCA and incorporate socio-economic factors for sustainability in the medicinal cannabis sector. Full article