Search Results (1,799)

A rigorous rate-based absorption model integrated with an improved thermodynamic framework was developed to simulate natural gas desulfurization using TMS–MDEA (Tetramethylene Sulfone–Methyldiethanolamine) aqueous solutions. The model was validated against 50 sets of industrial and experimental data, achieving R² values above 0.98 and average deviations within 5%. The model was formulated for steady-state operation of a trayed absorber integrated with flash and packed-bed regeneration and applicable over industrially relevant ranges (absorber pressure 3–6.4 MPa; gas–liquid ratio 350–720; flash pressure 0.3–0.6 MPa; packing height ≥ 3 m). The results indicate that H₂S can be removed almost completely (>99.9%); CO₂ and COS achieve 70–85% and 75–83% removal, respectively; and CH₃SH removal exceeds 90% under typical conditions. Parametric analysis revealed that higher tray numbers, weir heights, and pressures enhance absorption efficiency, whereas hydrocarbon solubility increases with carbon number and is strongly affected by pressure and the gas–liquid ratio. In the desorption section, flash regeneration efficiently strips light hydrocarbons, with decreasing desorption efficiency from CH₄ to C₆H₁₄. This study provides quantitative insights into the coupled absorption–desorption process and offers practical guidance for process design, solvent selection, and energy-efficient operation in natural gas purification. Full article

With the goal of achieving carbon neutrality, promoting the clean and low-carbon transformation of energy assets, as exemplified by existing thermal power units, has emerged as a pivotal challenge in addressing climate change and achieving sustainable development. Arrangements and technologies such as the electricity–carbon–certificate multi-market, microgrids with direct green power connections, and carbon capture and storage (CCS) retrofitting provide favorable conditions for facing the aforementioned challenge. Based on an analysis of how liquid-storage CCS retrofitting affects the flexibility of thermal power units, this manuscript proposes a bi-level optimization model and solution method for capacity allocation for grid-connected microgrids, while considering CCS retrofits under multi-markets. This approach overcomes two key deficiencies in the existing research: first, neglecting the relationship between electricity–carbon coupling characteristics and unit flexibility and its potential impacts, and second, the significant deviation of scenarios constructed from real policy and market environments, which limits its ability to provide timely and relevant references. A case study in southern China demonstrates that first, multi-market implementation significantly boosts microgrids’ investment in and absolute consumption of renewable energy. However, its effect on reducing carbon emissions is limited, and renewable power curtailment may surge, potentially deviating from the original intent of carbon neutrality policies. In this case study, renewable energy installed capacity and consumption rose by 17.09% and 22.64%, respectively, while net carbon emissions decreased by only 3.32%, and curtailed power nearly doubled. Second, introducing liquid-storage CCS, which decouples the CO₂ absorption and desorption processes, into the capacity allocation significantly enhances microgrid flexibility, markedly reduces the risk of overcapacity in renewable energy units, and enhances investment efficiency. In this case study, following CCS retrofits, renewable energy unit installed capacity decreased by 24%, while consumption dropped by only 7.28%, utilization hours increased by 22%, and the curtailment declined by 78.05%. Third, although CCS retrofitting can significantly reduce microgrid carbon emissions, factors such as current carbon prices, technological efficiency, and economic characteristics hinder large-scale adoption. In this case study, under multi-markets, CCS retrofitting reduced net carbon emissions by 86.16%, but the annualized total cost rose by 3.68%. Finally, based on the aforementioned findings, this manuscript discusses implications for microgrid development decision making, CCS industrialization, and market mechanisms from the perspectives of research directions, policy formulation, and practical work. Full article

To address the issues of insufficient capacity and difficult regeneration of adsorbents for phosphate removal from wastewater, in this study, FeOOH/Al₂O₃ adsorbents were successfully developed by in situ growing amorphous iron oxyhydroxide (FeOOH) within the pores of alumina (Al₂O₃) using a simple method. The physicochemical properties of FeOOH/Al₂O₃ adsorbents were characterized using X-ray Diffraction (XRD), N₂ adsorption/desorption analysis, and scanning electron microscopy (SEM). Additionally, their phosphate adsorption properties were comparatively investigated. The results revealed that FO-A-3, one of the FeOOH/Al₂O₃ samples prepared with Fe/Al molar ratio of 0.47, exhibited excellent adsorption capacity and a relatively fast adsorption rate, surpassing those of Al₂O₃ and amorphous FeOOH alone. The adsorption process of phosphate using FO-A-3 conformed to the pseudo-second-order kinetic model and the Langmuir isotherm model, with a maximum adsorption capacity of 131.00 mg/g. To tackle the problem of poor regeneration performance, this study innovatively proposed a repeatable and simple regeneration strategy. Experiments demonstrated that FO-A-3 maintained a relatively high adsorption capacity after four cycles of regeneration. Full article

Mitigating climate change through the reduction of atmospheric CO₂ emissions remains a critical global priority. Solid adsorbents, particularly shales, have become promising options for CO₂ storage due to their favorable structural and chemical properties. In this study, a solid sorbent was developed by pyrolyzing shale at 800 °C under a nitrogen (N₂) atmospheric condition, yielding spent shale. The key physicochemical properties influencing CO₂ sorption were characterized using X-ray diffraction (XRD), Field Emission Scanning Electron Microscopy (FESEM), Brunauer–Emmett–Teller (BET) surface area analysis, and Temperature-Programmed Desorption (TPD). Mineralogical analysis revealed the presence of quartz, feldspars, clays, and carbonate minerals. The spent shale exhibited surface areas of 30–34 m²/g and pore diameters ranging from 3 to 10 nm. TPD results confirmed the presence of active adsorption sites, with a maximum CO₂ sorption capacity of about 1.62 mmol/g—surpassing several commercial sorbents. Adsorption behavior was best described by the Sips and Toth isotherm models (R² > 0.99), indicating multilayer and heterogeneous adsorption processes. Kinetic modeling using both pseudo-first-order and pseudo-second-order equations revealed that CO₂ uptake was governed by both diffusion and chemisorption mechanisms. These findings positioned spent shale as a low-cost, efficient sorbent for CO₂ storage, promoting circular resource utilization and advancing sustainable carbon management strategies. This novel shale-derived material offers a competitive pathway for carbon capture, storage, and sequestration applications. Full article

Coalbed-methane (CBM) extraction involves complex processes such as desorption, diffusion, and seepage, significantly increasing the difficulty of numerical simulation. To enable efficient CBM development, this study establishes an integrated simulation workflow for CBM, encompassing geological modeling, geomechanical modeling, hydraulic fracture simulation, and production dynamic simulation. Specifically, the unconventional fracture model (UFM), integrated within the Petrel commercial software, is applied for fracture simulation, with an unstructured grid constructing the CBM production model. Subsequently, based on the case study of well pad A in the Daning–Jixian block, the effects of well spacing and hydraulic fractures on gas production were analyzed. The results indicate that the significant stress difference between the coal seam and the top/bottom strata constrains fracture height, with simulated hydraulic fractures ranging from 169.79 to 215.84 m in length, 8.91 to 10.45 m in height, and 121.92 to 248.71 mD·m in conductivity. Due to the low matrix permeability, pressure drop and desorption primarily occur in the stimulated reservoir volume (SRV) region. The calibrated model predicts a 10-year cumulative gas production of 616 × 10⁴ m³ for the well group, with a recovery rate of 10.17%, indicating significant potential for enhancing recovery rates. Maximum cumulative gas production occurs when well spacing slightly exceeds fracture length. Beyond 200 mD·m, fracture conductivity has diminishing returns on production. Fracture length increases from 100 to 250 m show near-linear growth in production, but further increases yield smaller gains. These findings provide valuable insights for evaluating development performance and exploiting remaining gas resources for CBM. Full article

Bottom sediments play a central role in regulating contaminant dynamics in aquatic systems. They act as both storage sites and reactive zones where contaminants undergo transformation, sequestration, or remobilization. Contaminants primarily enter sediments through anthropogenic activities, including agricultural runoff, industrial effluents, wastewater discharge, urban runoff, and mining operations. This review focuses on six major contaminant groups, including nutrients, heavy metals, pharmaceutical residues, pesticides, polycyclic aromatic hydrocarbons, and microplastics, and examines the mechanistic processes that govern their fate in sediments. The main mechanisms includesorption–desorption on minerals and organic materials, sedimentation, and redox processes that regulate metal immobilization and sulfide formation. The persistence and mobility of contaminants are also influenced by synergistic or antagonistic interactions among pollutants, microbial transformation of organic compounds, and oxidative degradation of microplastics by reactive oxygen species. Contaminants can affect benthic communities by causing toxic effects and oxygen depletion. They also may alter microbial and macrofaunal populations and contribute to bioaccumulation and biomagnification. Ultimately, these insights are important for predicting contaminant behavior and assessing ecological risks, which directly informs the development of effective environmental monitoring programs and sustainable sediment remediation strategies for the long-term protection of aquatic ecosystems. Full article

The urgent global issue of climate change caused by rising carbon dioxide (CO₂) levels has led to the widespread use of gas separation processes. Among the available processes, chemical absorption has received more attention due to its maturity and higher efficiency compared to others. However, the high energy consumption during the desorption step poses several technical challenges, limiting its industrial applications. To overcome those challenges, several research studies have been conducted to improve the performance of the desorption process. In particular, various types of catalysts have been tested to improve the performance of the CO₂ desorption process. Among the available catalysts, Titanium Oxyhydrate (TiO(OH)₂) has shown remarkable characteristics for replacing conventional catalysts, mainly due to its stability and the potential for increasing the CO₂ desorption rate. However, limited studies have been conducted to evaluate the performance of the CO₂ desorption process, especially by utilizing commercial solvents such as piperazine (PZ) promoted methyldiethanolamine (MDEA). Hence, this study aims to evaluate the stability of TiO(OH)₂ as a catalyst during the CO₂ desorption process using various characterization techniques. The CO₂ desorption performance is also assessed under different operating conditions. Moreover, the regeneration energy is determined and reported as the sensible heat duty per released CO₂. The results show no significant difference between fresh and cycled TiO(OH)₂, indicating its substantial thermal stability. Furthermore, a notable rise of 19.58% is observed in desorption rate while utilizing TiO(OH)₂ with a mass concentration of 5 wt%, reflecting less energy consumption. These findings suggest that TiO(OH)₂ could serve as a transformative catalyst in industrial-scale CO₂ desorption processes, potentially paving the way for more sustainable CO₂ capture technologies. Full article

Acetamiprid (ACE) and thiacloprid (THIA) are the dominant cyano-substituted neonicotinoids detected in fruit juices and bottled water, which raises food-safety concerns and regulatory scrutiny. Conventional purification with activated carbon or advanced oxidation shows limited selectivity and has a high energy demand. Covalent organic frameworks (COFs) offer tunable chemistry for targeted adsorption, yet no strategy exists to engineer COF sites that preferentially recognize the cyano group of ACE/THIA. Here, we synthesized a magnetic core-shell adsorbent, Fe₃O₄@COF(TBTD-BD)-Au, by growing cyano-affinitive Au nanoparticles on a Cl-decorated COF shell surrounding a Fe₃O₄ core. Under optimized conditions (pH 6.0, 25 °C), the Fe₃O₄@COF(TBTD-BD)-Au achieved maximum adsorption capacities of 157 mg g⁻¹ (ACE) and 156 mg g⁻¹ (THIA). Uptake followed pseudo-second-order kinetics and the Freundlich isotherm; thermodynamic analysis confirmed an endothermic, spontaneous process. Competitive tests showed >80% removal of ACE and THIA in the presence of four co-occurring neonicotinoids, and the adsorbent retained 91.5% of its initial capacity after six adsorption–desorption cycles. Synergistic Au-cyano coordination, Cl-mediated hydrogen bonding, and π–π stacking confinement confer high selectivity and capacity. This ligand-guided, post-functionalized COF provides promising potential in the field of food sample treatment for contaminant removal. Full article

Carbon dioxide (CO₂)-enhanced coalbed methane recovery involves a complex process of mixed-gas adsorption, desorption, and diffusion–transport. The literature suggests that an appropriate range of CO₂ injection pressure and an optimal injection time window are critical for coal seams with varying reservoir conditions. That is, higher pressure and longer injection periods do not necessarily lead to better displacement performance. Therefore, in this study, experimental research was conducted on the time-varying characteristics of the displacement–replacement effect of CO₂-enhanced methane (CH₄) extraction from coal seams, and the following results were obtained. (1) The process of displacement–replacement of CH₄ by CO₂ in coal seams can be divided into five stages: a stage of spontaneous CH₄ desorption caused by partial-pressure effects, a replacement-dominated stage, a stage where replacement and displacement act jointly, a displacement-dominated stage, and a stabilization stage. (2) For all three coal samples (anthracite, coking coal, and long-flame coal), cumulative CH₄ desorption increases with increasing CO₂ injection pressure below 5 MPa and finally stabilizes. However, when CO₂ injection pressure exceeds 5 MPa, the effect weakens, possibly due to the dynamic changes in CO₂ partial pressure. (3) The displacement–replacement ratio decreases with increasing CH₄ equilibrium pressure. Additionally, the larger the difference between the CO₂ injection pressure and the CH₄ equilibrium pressure, the better the displacement–replacement effect. Full article

Eco-friendly clay-based adsorbents with low cost and high adsorption capacity for toxic dyes have attracted significant attention. In this study, a novel citric acid-modified sepiolite (CA-SEP) composite was developed for the efficient removal of methylene blue (MB) from aqueous solutions. The morphological, crystalline, and structural properties of the composite were characterized using XRD, FTIR, SEM, and BET analyses. Compared to pristine SEP, CA-SEP exhibited a 2.6-fold increase in adsorption capacity for MB and demonstrated excellent reusability. The effects of key parameters—including solution pH (2.0–10.0), contact time (0–300 min), adsorbent dosage (0.2–2.0 g/L), and initial MB concentration (10–150 mg/L)—on adsorption performance were systematically investigated. Modeling results indicated that the Sips isotherm provided the optimal fit for the equilibrium data. In kinetic studies, the adsorption process was best described by the pseudo-second-order model. The maximum adsorption capacity of CA-SEP for MB was estimated to be 40.61 mg/g. Moreover, the adsorbent retained high removal efficiency after five adsorption-desorption cycles, demonstrating good regenerability. These results indicate that CA-SEP is a highly efficient, sustainable, and economically viable adsorbent for the elimination of MB from contaminated water. Full article

Magnetic biochar (Zn/Fe-BC) was prepared from jujube branches via an impregnation pyrolysis–coprecipitation technique to eliminate Cr(VI) from water. ZnFe₂O₄ was introduced through ZnCl₂-based impregnation and pyrolysis, which can regulate the microstructure of hydrocarbon frameworks. Furthermore, FeSO₄·7H₂O was used as the precursor for co-precipitation to embed Fe₃O₄ into the material, improving its reducibility and magnetism. The results demonstrated that Zn/Fe-BC exhibited excellent Cr(VI) removal efficiency. Under optimal conditions (an initial Cr(VI) concentration of 50 mg/L, pH 2, and an adsorbent dosage of 2 g/L), the maximum adsorption capacity of Zn/Fe-BC reached 27.85 mg/g, which was significantly higher than that of unmodified biochar (23.20 mg/g). Following five cycles of adsorption and desorption, the desorption efficiency was still higher than 60.35%. The following were the inhibitory effects of coexisting anions on the elimination of Cr(VI): CO₃²⁻ > PO₄³⁻ > SO₄²⁻ > NO₃⁻. According to kinetic and isothermal adsorption experiments, the adsorption process adhered to the Freundlich isotherm and followed a pseudo-second-order kinetic model, indicating a multilayer adsorption process. Cr(VI) removal by Zn/Fe-BC was driven by physical adsorption and chemical reduction, involving a synergistic combination of electrostatic attraction, reduction, complexation, precipitation, and pore filling. These findings demonstrate the potential of the Zn/Fe-BC magnetic biochar as an effective adsorbent for Cr(VI) remediation in water treatment applications. Full article

Alkylic molecules are found as some of the main components of natural essential oils. These essential oils offer several therapeutic properties in skin treatments and cosmetics. Systems providing controlled release of these molecules through the skin tissue are a challenge for their applications. This work explores some properties of the crystal structure of α-pinene and the adsorption and desorption of five terpenoid components of essential oils, such as α-pinene, limonene, β-ocimene, β-caryophyllene, and β-elemene, in the confined surfaces provided by natural clay minerals, particularly montmorillonite (MNT). These terpenoids have a methyl-ethenyl group as their common structural feature. Molecular modelling calculations have been applied at the atomic scale, including force fields, quantum mechanical methods, and molecular dynamics simulations. We calculated the crystallographic and spectroscopic properties of the α-pinene crystal via density functional theory (DFT)-level calculations, which were very close to the known experimental data. Moreover, this work explored the adsorption and desorption of these molecules in confined surfaces provided by MNT. Molecular dynamics simulations also showed the adsorption of these organics in the confined interlayer space of MNT at room temperature and allowed us to know the diffusion coefficient of these adsorbates in this material. The direct adsorption process of these molecules in the vapour phase is not energetically favourable, suggesting the use of non-aqueous solvents and kinetics and thermodynamic conditions for this process. However, the release of these molecules into aqueous media are energetically favourable, predicting that MNT–essential oil can be an excellent pharmaceutical formulation to be delivered in skin as a bioactive preparation with anti-inflammatory or cosmetic power. This research was performed to predict possible therapeutic applications for future experimental works. Full article

The dehydration of fructose and glucose to 5-hydroxymethylfurfural (HMF) in water solution was carried out in the presence of functionalized heteropolyanion-based heterogeneous catalysts. Two catalysts were prepared by immobilizing the Keggin polyoxometalate H₃PW₁₂O₄₀ (PW₁₂) onto nanoSiO₂ by the use of imidazoline and -SO₃⁻ surface species through acid–base reactions. The catalysts were characterized by N₂ adsorption–desorption isotherms, XRD, TGA, FTIR, solid-state NMR, SEM, and acidity–basicity measurements. Catalytic reactions in batch conditions were performed at 165 °C in the presence of suspended catalysts, and the yield of furfural and 5-hydroxymethylfurfural (5-HMF) was determined. The catalytic activity of the materials was tested for sugars at 1M concentration in a water solution. The valorization of sugars (fructose and glucose) was found to be more effective in the case of fructose. Furthermore, the two catalysts in which the heteropolyacid was immobilized showed activity similar to that observed for naked PW₁₂ (reaction in homogeneous phase), despite the heterogeneous nature of the process, but with the advantage of easier separation at the end of the reaction by simple filtration. The material’s substantial stability was demonstrated through three consecutive catalytic test cycles, in which the same catalyst was recovered after each experiment and washed several times with hot water. Finally, tests devoted to the valorization of sugars contained in wastewater from the brewing industry provided a poor yield in 5-HMF, indicating that the catalysts prepared here were, unfortunately, not suitable for this transformation under the conditions tested. This was because the catalysts prepared in this work showed a low capacity to transform glucose (the most present sugar in the carbohydrate fraction of this biomass) into furans. Full article

To address the imbalance in energy supply and demand across different regions and seasons, the thermochemical conversion process was selected to efficiently utilize surplus energy. In the search for suitable novel materials, this study developed a porous matrix “in-salt” composite using a carbonized metal-organic framework as the carrier and LiCl as the primary reactant. When exposed to water vapor, the innovative material enabled both adsorption and desorption of water vapor, leading to the release and storage of thermal energy, thereby achieving effective energy storage. Using Zn(NO₃)₂·6H₂O and Co(NO₃)₂·6H₂O as metal ion sources and 2-methylimidazole as the ligand, bimetallic zeolitic imidazolate frameworks (BMZIFs) were fabricated via the liquid-phase precipitation method. The composite specimen prepared at a carbonization temperature of 1000 °C with a 20% LiCl mass concentration exhibited the most promising thermal storage performance, achieving the highest capacity, with a final water loss of 53.56% and a stable water adsorption capacity of about 0.831 g·g⁻¹. Full article

Background/Objectives: Antimicrobial resistance is a critical global health challenge. Among resistant pathogens, the group of bacteria collectively referred to as ESKAPE (Enterococcus faecium, Staphylococcus aureus, Klebsiella pneumoniae, Acinetobacter baumannii, Pseudomonas aeruginosa, and Enterobacter spp.) is of particular concern due to their ability to evade multiple classes of antimicrobials. This study aimed to investigate the occurrence and resistance patterns of ESKAPE bacteria in wild birds from Northern and Central Italy sites, and to assess the presence of other bacteria of public health relevance. Methods: Cloacal swabs were collected from 141 wild birds. Samples were processed on selective and differential media, and bacterial identification was performed using Matrix-Assisted Laser Desorption/Ionization Time-of-Flight Mass Spectrometry. Antimicrobial susceptibility was evaluated through Minimum Inhibitory Concentration assays and interpreted according to international guidelines. Results: Thirty-seven isolates belonging to the ESKAPE group were identified: E. faecium (n = 10), K. pneumoniae (n = 9), P. aeruginosa (n = 8), Enterobacter spp. (n = 7), S. aureus (n = 2), and A. baumannii (n = 1). Multidrug-resistant isolates were observed among K. pneumoniae and Enterobacter hormaechei. Escherichia coli, although not included in the ESKAPE group, was frequently detected and often co-isolated with clinically relevant bacteria, highlighting its potential role as a reservoir of resistance genes. Conclusions: Wild birds can harbor resistant bacteria of clinical importance, including multidrug-resistant ESKAPE species. Their presence in avian populations underscores the role of wildlife in the environmental dissemination of antimicrobial resistance, with implications for both animal and human health. Full article