Search Results (577)

The global cement industry remains a significant contributor to carbon dioxide (CO₂) emissions, prompting substantial research efforts toward sustainable construction materials. Lithium slag (LS), a by-product of lithium extraction, has attracted attention as a supplementary cementitious material (SCM). This review synthesizes experimental findings on LS replacement levels, fresh-state behavior, mechanical performance (compressive, tensile, and flexural strengths), time-dependent deformation (shrinkage and creep), and durability (sulfate, acid, abrasion, and thermal) of LS-modified concretes. Statistical analysis identifies an optimal LS dosage of 20–30% (average 24%) for maximizing compressive strength and long-term durability, with 40% as a practical upper limit for tensile and flexural performance. Fresh-state tests show that workability losses at high LS content can be mitigated via superplasticizers. Drying shrinkage and creep strains decrease in a dose-dependent manner with up to 30% LS. High-volume (40%) LS blends achieve up to an 18% gain in 180-day compressive strength and >30% reduction in permeability metrics. Under elevated temperatures, 20% LS mixes retain up to 50% more residual strength than controls. In advanced systems—autoclaved aerated concrete (AAC), one-part geopolymers, and recycled aggregate composites—LS further enhances both microstructural densification and durability. In particular, LS emerges as a versatile SCM that optimizes mechanical and durability performance, supports material circularity, and reduces the carbon footprint. Full article

Against the backdrop of global energy transition and strict environmental regulations, supercritical carbon dioxide (scCO₂) fracturing and oil displacement technologies have emerged as pivotal green approaches in shale gas exploitation, offering the dual advantages of zero water consumption and carbon sequestration. However, the inherent low viscosity of scCO₂ severely restricts its sand-carrying capacity, fracture propagation efficiency, and oil recovery rate, necessitating the urgent development of high-performance thickeners. The current research on scCO₂ thickeners faces a critical trade-off: traditional fluorinated polymers exhibit excellent philicity CO₂, but suffer from high costs and environmental hazards, while non-fluorinated systems often struggle to balance solubility and thickening performance. The development of new thickeners primarily involves two directions. On one hand, efforts focus on modifying non-fluorinated polymers, driven by environmental protection needs—traditional fluorinated thickeners may cause environmental pollution, and improving non-fluorinated polymers can maintain good thickening performance while reducing environmental impacts. On the other hand, there is a commitment to developing non-noble metal-catalyzed siloxane modification and synthesis processes, aiming to enhance the technical and economic feasibility of scCO₂ thickeners. Compared with noble metal catalysts like platinum, non-noble metal catalysts can reduce production costs, making the synthesis process more economically viable for large-scale industrial applications. These studies are crucial for promoting the practical application of scCO₂ technology in unconventional oil and gas development, including improving fracturing efficiency and oil displacement efficiency, and providing new technical support for the sustainable development of the energy industry. This study innovatively designed an amphiphilic modified amino silicone oil polymer (MA-co-MPEGA-AS) by combining maleic anhydride (MA), methoxy polyethylene glycol acrylate (MPEGA), and amino silicone oil (AS) through a molecular bridge strategy. The synthesis process involved three key steps: radical polymerization of MA and MPEGA, amidation with AS, and in situ network formation. Fourier transform infrared spectroscopy (FT-IR) confirmed the successful introduction of ether-based CO₂-philic groups. Rheological tests conducted under scCO₂ conditions demonstrated a 114-fold increase in viscosity for MA-co-MPEGA-AS. Mechanistic studies revealed that the ether oxygen atoms (Lewis base) in MPEGA formed dipole–quadrupole interactions with CO₂ (Lewis acid), enhancing solubility by 47%. Simultaneously, the self-assembly of siloxane chains into a three-dimensional network suppressed interlayer sliding in scCO₂ and maintained over 90% viscosity retention at 80 °C. This fluorine-free design eliminates the need for platinum-based catalysts and reduces production costs compared to fluorinated polymers. The hierarchical interactions (coordination bonds and hydrogen bonds) within the system provide a novel synthetic paradigm for scCO₂ thickeners. This research lays the foundation for green CO₂-based energy extraction technologies. Full article

In this study, we comprehensively analyzed material consumption (fuel, hydraulic oil, lubricants, and AdBlue fluid) and estimated carbon dioxide emissions during logging operations. This study was carried out in the northeastern part of Poland. Four harvesters and four forwarders representing two manufacturers (John Deere-Deere & Co., Moline, USA, and Komatsu Forest AB, Umeå, Sweden) were analyzed to compare their operational efficiency and constructional influences on overall operating costs. Due to differences in engine emission standards, approximate greenhouse gas emissions were estimated. The results indicate that harvesters equipped with Stage V engines have lower fuel consumption, while large forwarders use more consumables than small ones per hour and cubic meter of harvested and extracted timber. A strong positive correlation was observed between total machine time and fuel consumption (r = 0.81), as well as between machine time and total volume of timber harvested (r = 0.72). Older and larger machines showed about 40% higher combustion per unit of wood processed. Newer machines meeting higher emission standards (Stage V) generally achieved lower CO₂ and other GHG emissions compared to older models. Machines with Stage V engines emitted about 2.07 kg CO₂ per processing of 1 m³ of wood, while machines with older engine types emitted as much as 4.35 kg CO₂ per 1 m³—roughly half as much. These differences are even more pronounced in the context of nitrogen oxide (NO_x) emissions: the estimated NO_x emissions for the older engine types were as high as ~85 g per m³, while those for Stage V engines were only about 5 g per m³ of harvested wood. Continuing the study would need to expand the number of machines analyzed, as well as acquire more detailed performance data on individual operators. A tool that could make this possible would be fleet monitoring services offered by the manufacturers of the surveyed harvesters and forwards, such as Smart Forestry or Timber Manager. Full article

Light Detection and Ranging (LiDAR) provides three-dimensional information that can be used to extract tree parameter measurements such as height (H), canopy volume (CV), canopy diameter (CD), canopy area (CA), and tree stand density. LiDAR data does not directly give diameter at breast height (DBH), an important input into allometric equations to estimate biomass. The main objective of this study is to estimate tree DBH using existing allometric models. Specifically, it compares three global DBH pantropical models to calculate DBH and to estimate the aboveground biomass (AGB) of the Lake Broadwater Forest located in Southeast (SE) Queensland, Australia. LiDAR data collected in mid-2022 was used to test these models, with field validation data collected at the beginning of 2024. The three DBH estimation models—the Jucker model, Gonzalez-Benecke model 1, and Gonzalez-Benecke model 2—all used tree H, and the Jucker and Gonzalez-Benecke model 2 additionally used CD and CA, respectively. Model performance was assessed using five statistical metrics: root mean squared error (RMSE), mean absolute error (MAE), mean absolute percentage error (MAPE), percentage bias (MBias), and the coefficient of determination (R²). The Jucker model was the best-performing model, followed by Gonzalez-Benecke model 2 and Gonzalez-Benecke model 1. The Jucker model had an RMSE of 8.7 cm, an MAE of −13.54 cm, an MAPE of 7%, an MBias of 13.73 cm, and an R² of 0.9005. The Chave AGB model was used to estimate the AGB at the tree, plot, and per hectare levels using the Jucker model-calculated DBH and the field-measured DBH. AGB was used to estimate total biomass, dry weight, carbon (C), and carbon dioxide (CO₂) sequestered per hectare. The Lake Broadwater Forest was estimated to have an AGB of 161.5 Mg/ha in 2022, a Total C of 65.6 Mg/ha, and a CO₂ sequestered of 240.7 Mg/ha in 2022. These findings highlight the substantial carbon storage potential of the Lake Broadwater Forest, reinforcing the opportunity for landholders to participate in the carbon credit systems, which offer financial benefits and enable contributions to carbon mitigation programs, thereby helping to meet national and global carbon reduction targets. Full article

The present study investigated the efficacy of edible coatings formulated with gellan gum and lemon peel extract (LPE) in preserving the postharvest quality of cherry tomatoes (Solanum lycopersicum var. cerasiforme). Selected fruits exhibiting uniform ripeness and free from defects were sanitized and coated with solutions containing different HAG/LAG (high- and low-acyl gellan gum) ratios, incorporating 4.0% (w/v) LPE. Physicochemical and physiological parameters, including soluble solids content, weight loss, pH, titratable acidity, oxygen consumption, carbon dioxide and ethylene production, skin redness (a*/b* ratio), and decay incidence, were systematically assessed under storage conditions of 25 °C and 70% relative humidity. HAG-coated fruits showed the lowest weight loss (1.08%), higher soluble solids (7.11 °Brix), and greater firmness (3.11 N/mm²) compared to uncoated controls. Moreover, they exhibited reduced oxygen consumption (0.06 mg·kg⁻¹·h⁻¹), ethylene production (3.10 mg·kg⁻¹·h⁻¹), and decay rate (2%). Redness was better preserved, and decay rates were substantially (p < 0.05) reduced throughout the storage period. These findings highlight the potential of HAG-based edible coatings enriched with LPE as an innovative postharvest technology to extend shelf life, maintain quality attributes, and reduce postharvest losses in cherry tomatoes. Full article

According to the literature, Schinus molle (SM) is an important source of bioactive phytochemicals, but the phytochemical content and composition of this species, which grows in high Andean geographic zones such as Tarma (Peru), is not known. In an effort to fill this gap, our work investigated the supercritical carbon dioxide extraction of SM leaves at three temperature levels (35, 45, and 55 °C) and three pressure levels (150, 250, and 350 bar). The results revealed the highest yield of extract at 150 bar, 45 °C, and 3.28 g CO₂/min. Under these conditions, the overall extraction curves (OEC) were modeled using the Spline, logistic, and Esquível models, allowing the generation of mass transfer parameters for SFE at the optimized conditions, resulting in a similar correlation with experimental data. Twenty-six compounds were identified in the SFE extract of SM leaves. The most abundant compound classes were sesquiterpenoids (57.17%), sesquiterpenes (24.50%), and triterpenoids (10.48%); of each class, the most abundant compounds were shyobunol (33.60%), bicyclogermacrene (12.68%), and lupeone (6.58%), respectively. The compounds detected possess bioactive properties that support further studies on the application of SFE extracts of SM as a functional ingredient in commercial products. Full article

This study investigates the sequential extraction of lipids and saponins from C. frondosa viscera. Lipids were extracted using supercritical carbon dioxide (scCO₂) in the presence of ethanol (EtOH) as a co-solvent. Subsequently, the lipid-extracted viscera underwent three saponin extraction approaches, scCO₂-scCO₂, scCO₂-EtOH, and scCO₂-hot water, resulting in saponin-rich extracts. Process parameter investigation for saponin extraction from scCO₂-defatted viscera revealed minimal effects of temperature, pressure, extraction time, static extraction, and EtOH concentration on saponin yields, allowing for milder operational conditions (35 °C, 20 MPa, 30 min dynamic extraction, 75% EtOH at 0.5 mL/min) to achieve energy-efficient recovery. Continuous EtOH feeding predominates the scCO₂ extraction of saponins. The sequential scCO₂ extraction of lipid and saponins yielded saponins at 9.13 mg OAE/g, while scCO₂ extraction of lipid followed by a 24 h 70% EtOH extraction of saponins achieved 16.26 mg OAE/g, closely matching the optimized ultrasonic-assisted extraction of saponins (17.31 mg OAE/g) from hexane-defatted samples. Antioxidant activities of saponin-rich extracts obtained in the sequential scCO₂-EtOH extraction (17.12 ± 4.20% DPPH scavenging) and the sequential scCO₂-scCO₂ extraction (16.14 ± 1.98%) were comparable to BHT (20.39 ± 0.68%), surpassing that of hexane-defatted ultrasonic extracts (8.11 ± 1.16%). The optimized scCO₂-EtOH method offers a sustainable alternative, eliminating toxic solvents while maintaining high saponin yields and bioactivity. Full article

The aim of this study was to use high-pressure extraction methods to obtain compounds of different classes from the leaves of Pereskia aculeata Mill. For this purpose, Supercritical Fluid Extraction (SFE) and Pressurized Liquid Extraction (PLE) were used. SFE was performed with Pereskia aculeata leaves to evaluate the application of propane and carbon dioxide as solvents, and the residual biomass from this stage was used in PLE with hydroethanolic solvent. The extracts were characterized in relation to the content of phenolic compounds, antioxidant potential and content of nonpolar compounds. In the first stage, despite the low yield (1.09–1.94%) compared to PLE (16.56–19.26%), the extracts presented a high content of lipophilic compounds (squalene, octacosanol, α-tocopherol and β-sitosterol) compared to the PLE technique. The sequential extraction process benefited the greater recovery of phenolic compounds and extracts with greater antioxidant potential. Caffeic and nicotinic acids were the major compounds identified in the phenolic profile. The processes applied did not influence the protein content of the final extraction residue, which was similar to that of the in natura leaf. The results and approach demonstrate that sequential extraction is an excellent alternative for the use of Pereskia aculeata, which allows for the production of extracts with varied composition and/or extracts with greater recovery of compounds available in the plant. Full article

Offshore synthetic fuel production and marine carbon dioxide removal can be enabled by direct ocean capture, which extracts carbon dioxide from the ocean that then can be used as a feedstock for fuel production or sequestered underground. To maximize carbon capture, plants require a variety of low-carbon energy sources to operate, such as variable renewable energy. However, the impacts of variable power on direct ocean capture have not yet been thoroughly investigated. To facilitate future deployments, a generalizable model for electrodialysis-based direct ocean capture plants is created to evaluate plant performance and electricity costs under intermittent power availability. This open-source Python-based model captures key aspects of the electrochemistry, ocean chemistry, post-processing, and operation scenarios under various conditions. To incorporate realistic energy supply dynamics and cost estimates, the model is coupled with the National Renewable Energy Laboratory’s H2Integrate tool, which simulates hybrid energy system performance profiles and costs. This integrated framework is designed to provide system-level insights while maintaining computational efficiency and flexibility for scenario exploration. Initial evaluations show similar results to those predicted by the industry, and demonstrate how a given plant could function with variable power in different deployment locations, such as with wind energy off the coast of Texas and with wind and wave energy off the coast of Oregon. The results suggest that electrochemical systems with greater tolerances for power variability and low minimum power requirements may offer operational advantages in variable-energy contexts. However, further research is needed to quantify these benefits and evaluate their implications across different deployment scenarios. Full article

This study investigated the use of supercritical carbon dioxide (CO₂) to extract bioactive compounds from Thai fingerroot (Boesenbergia rotunda), focusing on the effects of pressure, temperature, CO₂ flow rate, and ethanol co-solvent concentration. A central composite design within a response surface methodology framework was employed to optimize the total extraction yield, total phenolic content (TPC), and total flavonoid content (TFC). Conventional ethanol maceration was used as a benchmark. High-performance liquid chromatography identified the major compounds in the extracts, such as pinostrobin and pinocembrin. The results showed that the yield, TPC, and TFC increased with higher pressure, CO₂ flow rate, and co-solvent levels, whereas higher temperatures had a negative effect (p ≤ 0.05). Interactions between pressure and temperature favored the yield and TPC but not TFC. The optimal conditions—250 bar, 45 °C, 3 L/min CO₂ flow rate, and 100% ethanol—produced a yield of 28.67%, TPC of 354.578 mg GAE/g, and TFC of 273.479 mg QE/g. These values exceeded those obtained using conventional extraction (9.91% yield, 332.86 mg GAE/g TPC, and 77.57 mg QE/g TFC at 60 min). The regression models showed strong predictive accuracy (R² > 0.9). Pinostrobin and pinocembrin were the dominant phenolic compounds. These findings demonstrate the superior efficiency of supercritical CO₂ extraction for isolating phenolic compounds from B. rotunda. Full article

This study systematically investigates the pore–fracture architecture of deep coal seams in the JiaTan (JT) block of the Ordos Basin using an integrated suite of advanced techniques, including nuclear magnetic resonance (NMR), high-pressure mercury intrusion, low-temperature nitrogen adsorption, low-pressure carbon dioxide adsorption, and micro-computed tomography (micro-CT). These complementary methods enable a quantitative assessment of pore structures spanning nano- to microscale dimensions. The results reveal a pore system overwhelmingly dominated by micropores—accounting for more than 98% of the total pore volume—which play a central role in coalbed methane (CBM) storage. Microfractures, although limited in volumetric proportion, markedly enhance permeability by forming critical flow pathways. Together, these features establish a dual-porosity system that governs methane transport and recovery in deep coal reservoirs. The multiscale characterization employed here proves essential for resolving reservoir heterogeneity and designing effective stimulation strategies. Notably, enhancing methane desorption in micropore-rich matrices and improving fracture connectivity are identified as key levers for optimizing deep CBM extraction. These insights offer a valuable foundation for the development of deep coalbed methane (DCBM) resources in the Ordos Basin and similar geological settings. Full article

Natural gas with a high carbon dioxide (CO₂) content presents significant operational and environmental challenges when used as a fuel. A high CO₂ content lowers the calorific value of natural gas, reducing its fuel efficiency and increasing the risk of corrosion in pipelines and processing equipment. Consequently, such natural gas must be purified to reduce the CO₂ content to acceptable levels before it can be effectively used as a fuel. Various technologies for natural gas purification are currently employed, primarily focusing on CO₂ removal. This research explores an innovative approach where highly contaminated natural gas is utilized to synthesize hydrogen for subsequent methanol production. Methanol synthesis necessitates both hydrogen and CO₂, integrating the use of by-products effectively in the production chain. Following the production of methanol, it is then converted into dimethyl ether (DME), a compound with considerable value as a clean fuel alternative due to its lower emissions when burnt. The open-source COCO simulator was used to model and simulate these processes, allowing for the creation of a detailed process flowsheet. The simulation covered four main stages: (1) purification of the natural gas to remove excess CO₂, (2) production of hydrogen, (3) synthesis of methanol using the hydrogen and captured CO₂, and (4) conversion of methanol to DME. This integrated approach mitigates the issues associated with high CO₂ content in natural gas and leverages this component as a valuable feedstock, demonstrating a comprehensive use of all extracted compounds. The proposed process illustrates a promising route for utilizing highly contaminated natural gas, potentially transforming an environmental liability into valuable chemical commodities. Full article

Air pollution is the world’s greatest environmental health risk. Pollutants that pose large health concerns are particulate matter (PM_2.5 and PM₁₀), ozone (O₃), carbon monoxide (CO), nitrogen dioxide (NO₂), and sulphur dioxide (SO₂). These compounds (especially PM_2.5 and PM₁₀) contribute to the onset of diseases, such as respiratory diseases (e.g., asthma, chronic obstructive pulmonary disease (COPD), or lung cancer) and cardiovascular diseases. Abatement interventions are implemented to reduce air pollution and thereby the risk of these diseases. This systematic review examined the published scientific evidence on the cost-effectiveness of strategies aimed at reducing or controlling air pollution and assessed the reporting quality of included studies. It employed rigorous data extraction and quality scoring procedures to ensure the reliability and validity of our findings. Overall, there is substantial evidence supporting the cost-effectiveness of interventions aimed at reducing air pollution. Seventy-four studies and four policy reports were included in this review. Predominantly, cost–benefit analyses have been reported (n = 40), reflecting the multisectoral impacts and associated costs of air pollution. Only four cost–utility analyses were found, indicating the need for more research within this domain. Additionally, eight articles reported one or more non-economic results. Thirty-nine studies focused on particulate matter (PM), and eleven focused on nitrogen oxides (NOx). The quality assessment yielded moderate results. The heterogeneity of studies and moderate quality of reporting make it difficult to compare results and draw definitive conclusions. Full article

Reducing carbon dioxide emissions is a key priority in the European Union, which aims to achieve carbon neutrality by 2050. Construction has a key role to play in this effort, as it is responsible for a significant proportion of greenhouse gas emissions, especially due to cement production. At the same time, waste reuse emerges as a key strategy within the circular economy, another pillar of European policies. By valuing byproducts and waste, such as construction and demolition waste (CDW), it is possible to reduce the extraction of natural resources, amount of waste sent to landfills, and emissions associated with the production of new materials. This study, with the main objective of evaluating the possibility of using CDW as supplementary cementitious materials, emerges as a possible solution to reduce these problems. Two CDW treatment methods were used: (i) mechanical grinding and (ii) calcination. The mechanical grinding method, even with the use of laboratory equipment, has shown that it is possible to obtain CDW particles with characteristics suitable for replacing cement. For the calcination process, temperatures between 600 °C and 800 °C were the most suitable. The results proved that the replacement of cement by CDW in pastes resulted in suitable behavior for the construction industry, having revealed an incorporation content of up to 25% CDW, a compressive strength and strength activity index higher than that found for pastes developed with fly ash. Regarding the calcination process, this revealed an improvement in the compressive strength of the developed pastes, resulting in an increase in strength activity index of between 7 and 10%. Full article

In rocketry today, conventional hypergolic propellant combinations typically use hydrazine-derived fuels and oxidizers based on nitrogen tetroxide. Due to their high toxicity and consequently expensive handling, safer alternatives, so-called “green hypergolics”, are currently being developed. The ionic liquid-based fuels [EMIM][SCN], HIP_11 and HIM_30, paired with highly concentrated hydrogen peroxide as an oxidizer, are three candidates for such green hypergolics, which are currently under research at the German Aerospace Center (DLR). These combinations have been shown to exhibit reliable hypergolic ignition. For a better understanding of the reaction process and to assess the risks in working with these propellants, it is desirable to determine their combustion products. A test setup was designed to extract the gaseous combustion products from hypergolic drop tests. The gas samples were analyzed using Fourier-transform infrared spectroscopy and the gaseous combustion products were determined from the infrared spectra. Additional tests with varied oxidizer concentration or alternative fuels were conducted to further investigate detailed aspects of the findings. It was concluded that [EMIM][SCN], HIP_11 and HIM_30 produce very similar sets of combustion products with hydrogen peroxide, including water vapor, carbon dioxide, carbon monoxide, hydrogen cyanide and sulfur dioxide. Finally, the combustion products were compared to the substances produced when thermally decomposing the fuels. This confirmed that the previously detected substances were caused by a reaction between hydrogen peroxide and the fuels, rather than by their thermal decomposition due to heating. Full article