Search Results (6,392)

Phosphorus-based compounds play a crucial role in agricultural productivity. However, excessive phosphorus discharge into water bodies contributes to eutrophication. This study proposes a circular approach for phosphorus recovery and reuse through the thermal valorization of Posidonia oceanica residues, an abundant marine biomass along Mediterranean coasts. After energy recovery from this waste (12.3 MJ kg⁻¹), the resulting ash was assessed as an effective adsorbent for aqueous phosphorus removal. Batch experiments were conducted to evaluate adsorption kinetics and equilibrium, considering the influence of key operational variables, such as temperature, pH, and adsorbent dosage. Under optimal conditions, the material achieved a maximum retention of approximately 55–60 mgP g⁻¹. The Freundlich model successfully describes the equilibrium isotherm data, indicating a heterogeneous adsorbent and an overall endothermic process. Phosphorus removal was favored at basic pH values (9.5–10.5), where the monohydrogen phosphate predominates. Leaching tests further revealed that saturated material releases phosphorus and other minerals in a manner clearly dependent on the final pH, with higher phosphorus release under more acidic conditions. These results suggest that Posidonia ash could serve as a low-cost adsorbent while also acting as a potential phosphorus source in soils. Full article

As the production of electric vehicles grows, the rare earth elements Pr and Nd become increasingly significant, as they are key in magnetic materials production. In order to achieve the green and efficient recovery of Pr and Nd from the rare earth leachate, this paper selected kaolinite and halloysite as adsorbents to conduct rare earth solution adsorption experiments for exploring the effects of the initial leachate concentration, the solution pH, and the adsorption temperature on the adsorption process. The adsorption characteristics of Pr and Nd by clay minerals were analyzed by quantum chemical calculation. The results showed that the adsorption effects of clay minerals on Pr and Nd decreased with the rise of leachate concentration. When leachate pH increased, the adsorption efficiency of kaolinite and halloysite for Pr firstly increased and then decreased, and the optimal adsorption efficiency was 13.33% and 24.778% at pH 6, respectively. The adsorption effects of kaolinite and halloysite on Nd enhanced gradually with the increase in pH, which increased to 15.925% and 30.482% at pH 7, respectively. With temperature increased, the adsorption of Pr and Nd by kaolinite and halloysite was positively correlated. The isothermal adsorption model was fitted to the experimental data, and it was found that the adsorption of Pr and Nd by kaolinite and halloysite was consistent with the Langmuir model, with R² above 0.96, indicating that the adsorption process was a single molecular layer adsorption. The results provide theoretical support for the effective recycling of Pr and Nd, which is of great significance for the utilization of rare earth resources in permanent magnets. Full article

Crop diseases cause significant losses in agricultural production; early capture and identification of disease spores enable disease monitoring and prevention. This study experimentally optimized the preparation of Au@Ag NRS (Gold core@Silver shell Nanorods) sol as a Surface-Enhanced Raman Scattering (SERS) enhancement reagent via a modified seed-mediated growth method. Using an existing microfluidic chip developed by the research group, disease spores were separated and enriched, followed by combining Au@Ag NRS with Crop Disease Spores through electrostatic adsorption. Raman spectroscopy was employed to collect SERS fingerprint spectra of Crop Disease Spores. The spectra underwent baseline correction using Adaptive Least Squares (ALS) and standardization via Standard Normal Variate (SNV). Dimensionality reduction preprocessing was performed using Principal Component Analysis (PCA) and Successive Projections Algorithm combined with Competitive Adaptive Reweighted Sampling (SCARS). Classification was then executed using Support Vector Machine (SVM) and Multilayer Perceptron (MLP). The SCARS-MLP model achieved the highest accuracy at 97.92% on the test set, while SCARS-SVM, PCA-SVM, and SCARS-MLP models attained test set accuracy of 95.83%, 95.24%, and 96.55%, respectively. Thus, the proposed Au@Ag NRS-based SERS technology can be applied to detect airborne disease spores, establishing an early and precise method for Crop Disease detection. Full article

Leaching mining of ion-adsorption rare earths degrades soil organic matter and hampers vegetation recovery. High-resolution UAV remote sensing enables large-scale monitoring of reclamation, yet vegetation detection accuracy is constrained by key challenges. Conventional three-channel detection struggles with terrain complexity, illumination variation, and shadow effects. Fixed UAV altitude and missing topographic data further cause resolution inconsistencies, posing major challenges for accurate vegetation detection in reclaimed land. To enhance multi-spectral vegetation detection, the model input is expanded from the traditional three channels to six channels, enabling full utilization of multi-spectral information. Furthermore, the Channel Attention and Global Pooling SPPF (CAGP-SPPF) module is introduced for multi-scale feature extraction, integrating global pooling and channel attention to capture multi-channel semantic information. In addition, the C2f_DynamicConv module replaces conventional convolutions in the neck network to strengthen high-dimensional feature transmission and reduce information loss, thereby improving detection accuracy. On the self-constructed reclaimed vegetation dataset, MRV-YOLO outperformed YOLOv8, with mAP@0.5 and mAP@0.5:0.95 increasing by 4.6% and 10.8%, respectively. Compared with RT-DETR, YOLOv3, YOLOv5, YOLOv6, YOLOv7, yolov7-tiny, YOLOv8-AS, YOLOv10, and YOLOv11, mAP@0.5 improved by 6.8%, 9.7%, 5.3%, 6.5%, 6.4%, 8.9%, 4.6%, 2.1%, and 5.4%, respectively. The results demonstrate that multichannel inputs incorporating near-infrared and dual red-edge bands significantly enhance detection accuracy for reclaimed vegetation in rare earth mining areas, providing technical support for ecological restoration monitoring. Full article

A versatile, clear, and accurate method for determining the steady states of multi-component diffusion through composite membranes is presented in this study. This method can be used for simulating and designing membranes with any support orientation with respect to the zeolite film. In the mathematical model of the membrane, it was assumed that mass transport in the zeolite layer occurs by surface diffusion in accordance with the generalized Maxwell–Stefan model. Diffusion in the macroporous support was described by the dusty gas model (DGM). An alternative model of diffusion in the zeolite was proposed to the universally accepted model, which uses a matrix of thermodynamic factors G. Thus, the difficulty of analytically determining this matrix for more complex adsorption equilibria was eliminated. This article is dedicated to methodological and cognitive aspects. The practical features of the method are illustrated using two gas mixtures as examples, namely {H₂, CO₂} and {H₂, n-C₄H₁₀}. The roles of zeolite and support in the separation of these mixtures are discussed. It was demonstrated under what circumstances the presence of the support can be neglected in the steady-state analysis of the membrane. The effect of the alternative application of the dusty gas model or viscous flow only in the microporous support was discussed. Full article

Molecular dynamics simulations were conducted using the attachment energy (AE) model to investigate the growth morphology of lead 2,4,6-trinitrororesorcinate (LTNR, lead styphnate) under vacuum and different solvents. The adsorption energy of LTNR on (001), (110), (011), (020), (111), (200), and (201) crystal planes were calculated. Meanwhile, the crystal morphology in solvents of ethanol, toluene, dichloromethane, acetone, dimethyl sulfoxide (DMSO), and water at 298 K was predicted by calculating the interaction energies between the solvents and crystal planes. The calculated results show that the morphology of LTNR crystals in different solvents is significantly different. In toluene, LTNR crystal morphologies are flat, while in pure solvents of ethanol, acetone, and DMSO, the number of crystal planes increases, and the crystal thickness is larger. In the water, LTNR tends to form tabular crystals, which is similar to the experimental results. Both radial distribution function (RDF) and mean squared displacement (MSD) analyses reveal that hydrogen bonding dominates the interactions between LTNR and solvent molecules. Solvent molecules with higher diffusion coefficients exhibit increased desorption tendencies from crystal surfaces, which may reduce their inhibitory effects on specific crystallographic planes. However, no direct correlation exists between solvent diffusion coefficients and crystal plane growth rates, suggesting that surface attachment kinetics or interfacial energy barriers play a more critical role in crystal growth. Full article

The accurate prediction of single-well production performance necessitates considering the multiple factors influencing the dynamic changes in coal seam permeability during deep coalbed methane (CBM) extraction. This study focuses on Block D of the Ordos Basin. The Langmuir monolayer adsorption model was selected to describe gas adsorption behavior, and a productivity prediction model for deep CBM was developed by coupling multiple dynamic effects, including stress sensitivity, matrix shrinkage, gas slippage, and coal fines production and blockage. The results indicate that the stress sensitivity coefficients of artificial fracture networks and cleat fractures are key factors affecting the accuracy of CBM productivity predictions. Under accurate stress sensitivity coefficients, the predicted daily gas production rates of the productivity model for single wells showed errors ranging from 1.89% to 14.22%, with a mean error of 8.15%, while the predicted daily water production rates had errors between 0.35% and 17.66%, with a mean error of 8.68%. This demonstrates that the established productivity prediction model for deep CBM aligns with field observations. The findings can provide valuable references for production performance analysis and development planning for deep CBM wells. Full article

Membranes were assessed on a bench scale for their performance in methylene blue dye separation. The sawdust, along with Brazilian clay and kaolin, were mixed and compacted by uniaxial pressing and sintered at 650 °C. The membranes were characterized by several techniques, including X-ray diffraction, scanning electron microscopy, porosity, mechanical strength, water uptake, and membrane hydrodynamic permeability. The results demonstrated that the incorporation of sawdust not only altered the pore morphology but also significantly improved water permeation and dye removal efficiency. The ceramic membrane had an average pore diameter of 0.346–0.622 µm and porosities ranging from 40.85 to 42.96%. The membranes were applied to the microfiltration of synthetic effluent containing methylene blue (MB) and, additionally, subjected to investigation of their adsorptive capacity. All membrane variants showed high hydrophilicity (contact angles < 60°) and achieved MB rejection efficiencies higher than 96%, demonstrating their efficiency in treating dye-contaminated effluents. Batch adsorption using ceramic membranes (M0–M3) removed 34.0–41.2% of methylene blue. Adsorption behavior fitted both Langmuir and Freundlich models, indicating mixed mono- and multilayer mechanisms. FTIR confirmed electrostatic interactions, hydrogen bonding, and possible π–π interactions in dye retention. Full article

The present study aims to develop 3D-structured adsorbents for carbon capture with the utilization of coal ash after its conversion into zeolites. For this purpose, printing paste mixtures with a viscosity of 800 Pa·s were developed based on an environmentally friendly and safe polymer binder filled with coal ash zeolite with the addition of bentonite as a filler. The optimal consistency of the printing mixtures for preserving the shape and dimensions of the 3D-printed structures was established. Various model configurations of the macrostructure of 3D adsorbents were developed, and the optimal settings of the extruding system for their printing were established. After calcination, the resulting 3D structures were studied using instrumental analysis techniques, investigating the influence of 3D structuring on the phase composition, surface characteristics, and adsorption capacity for CO₂ capture in comparison with the initial powder coal ash zeolite adsorbents. The role of compensating cations in terms of the adsorption ability of powders in 3D-printed adsorbents was investigated. The current study offers an innovative and previously unexplored approach to a more expedient and practically significant utilization of aluminosilicate solid waste and, in particular, coal ash, through their 3D structuring and outlines a new research and technological direction in the development of economically advantageous, technologically feasible, and environmentally friendly 3D adsorbents. Full article

Hydrogen has been explored as a greener alternative for greenhouse gas emissions reduction. Sodium borohydride (NaBH₄) is a favorable hydrogen carrier due to its high hydrogen content, safe handling, and rapid hydrogen release. This work presents a novel synthesis of the catalyst CoFe₂O₄/Fe₂O₃ using nanocellulose fibers (TCNF) as reactive templates for metal adsorption and subsequent calcination. The resulting material was tested for H₂ production from basic NaBH₄ aqueous solutions (10–55 °C). The catalyst’s composition is 74.8 wt% CoFe₂O₄, 25 wt% Fe₂O₃, and 0.2 wt% Fe₂(SO₄)₃ with agglomerated spheroidal particles (15–20 nm) and homogeneous Fe and Co distribution. The catalyst produced 1785 mL of H₂ in 15 min at 25 °C (50 mg catalyst, 4.0% NaBH₄, and 2.5 wt% NaOH), close to the stoichiometric maximum (2086 mL). The maximum H₂ generation rate (HGR) reached 3.55 L min⁻¹ g_cat⁻¹ at 40 °C. Activation energies were determined using empirical (38.4 ± 5.3 kJ mol⁻¹) and Langmuir–Hinshelwood (L–H) models (42.2 ± 5.8 kJ mol⁻¹), consistent with values for other Co-ferrite catalysts. Kinetic data fitted better to the L–H model, suggesting that boron complex adsorption precedes H₂ evolution. Full article

Over the past decade, two-dimensional materials have become a research hotspot in chemistry, physics, materials science, and electrical and optical engineering due to their excellent properties. Graphene is one of the earliest discovered 2D materials. The absence of a bandgap in pure graphene limits its application in digital electronics where switching behavior is essential. In the present study, researchers have proposed a variety of methods for tuning the graphene bandgap. Machine learning methodologies have demonstrated the capability to enhance the efficiency of materials research by automating the recording of characteristic parameters from the discovery and preparation of 2D materials, property calculations, and simulations, as well as by facilitating the extraction and summarization of governing principles. In this work, we use first principle calculations to build a dataset of graphene band gaps under various conditions, including the application of a perpendicular external electric field, nitrogen doping, and hydrogen atom adsorption. Support Vector Machine (SVM), Random Forest (RF), and Multi-Layer Perceptron (MLP) Regression were utilized to successfully predict the graphene bandgap, and the accuracy of the models was verified using first principles. Finally, the advantages and limitations of the three models were compared. Full article

In this work, the removal of Cu(II) ions from an aqueous effluent was studied using an Mg/Fe layered double hydroxide (LDH) as the adsorbent. The material was synthesized and characterized before and after the adsorption process to identify structural and morphological changes induced by copper uptake. Techniques such as X-ray diffraction (XRD), scanning electron microscopy with energy-dispersive spectroscopy (SEM-EDS), ultraviolet-visible spectroscopy (UV-Vis), Raman spectroscopy, and nitrogen physisorption (BET) were employed to confirm the interaction between the metal ions and the LDH surface. The LDH-Mg/Fe exhibited a high maximum adsorption capacity of 526 mg/g, and the adsorption kinetics followed a pseudo-second-order model, achieving over 90% removal of Cu(II) within 2.5 h. The Cu(II)-loaded material was subsequently evaluated as a sustainable catalyst in two applications: (i) an organic synthesis via “click” chemistry, reaching yields of up to 85%, and (ii) the decoloration of Congo Red via a Fenton-like process, achieving a decoloration efficiency of at least 84%. These dual uses demonstrate the potential of Cu(II)-loaded LDH as a cost-effective and environmentally friendly approach to simultaneous pollutant removal and catalytic valorization. Full article

Developing highly permeable and selective membranes for energy-efficient CO₂/CH₄ separation remains challenging. Mixed-matrix membranes (MMMs) integrating polymer matrices with metal–organic frameworks (MOFs) offer significant potential. However, rational filler–matrix matching presents substantial difficulties, constraining separation performance. In this work, defects were engineered within fluorinated MOF ZU-61 through the partial replacement of 4,4′-bipyridine linkers with pyridine modulators, producing high-porosity HP-ZU-61 nanoparticles exhibiting a 267% BET surface area enhancement (992.9 m² g⁻¹) over low-porosity ZU-61 (LP-ZU-61) (372.2 m² g⁻¹). The HP-ZU-61/6FDA-DAM MMMs (30 wt.%) demonstrated homogeneous filler dispersion and pre-served crystallinity, achieving a CO₂ permeability of 1626 barrer and CO₂/CH₄ selectivity (33), surpassing the 2008 Robeson upper bound. Solution-diffusion modeling indicated ligand deficiencies generated accelerated diffusion pathways, while defect-induced unsaturated metal sites functioned as strong CO₂ adsorption centers that maintained solubility selectivity. This study establishes defect engineering in fluorinated MOF-based MMMs as a practical strategy to concurrently overcome the permeability–selectivity trade-off for efficient CO₂ capture. Full article

In this paper, the interfacial bonding properties between (110)_NiTi and (200)_TiN interfaces, as well as the adsorption capacity of Cl⁻ on the surfaces of (110)_NiTi and (200)_TiN, were investigated using the first-principles computational method based on density functional theory (DFT). Four types of interfacial models between (110)_NiTi and (200)_TiN were developed. It was found that the interfacial bonding energies of the four interface models are greater than zero, indicating stable interface bonding between (110)_NiTi and (200)_TiN. For comparison, model III (N of (200)_TiN is located at the bridge size between Ti and Ni in (110)_NiTi) has the largest Wad value of 9.773 J/m², which is attributed to stronger N-Ti bonding at the interface. Based on interface model III, an interfacial model of Cl⁻ at three different adsorption locations (top, bridge, and hole) on the (110)_NiTi and (200)_TiN surfaces, respectively, was constructed. The results reveal that the adsorption energies of Cl⁻ on the surface of (110)_NiTi are significantly less than those of the Cl⁻ on the surface of (200)_TiN. This suggests that (110)_NiTi is more likely to react with Cl⁻. Hence, the introduction of a TiN layer on the surface of NiTi alloy can effectively improve its corrosion resistance. Full article

Excessive release of ammonium (NH₄⁺) into aquatic ecosystems can promote eutrophication. In this study, the natural adsorbents, coal (C) prepared from Hawthorn (Acacia caven) and coal fly ash obtained from C, were used to remove NH₄⁺ from aqueous systems through batch adsorption–desorption studies. Both adsorbents were physically and chemically characterized, while Fourier-transform infrared spectroscopy and zeta potential were used to understand the surface functional groups and surface charge characteristics. CFA showed a higher pH, BET specific surface area, electrical conductivity and higher % values for CaO and MgO than C. Kinetic studies of NH₄⁺ adsorption at pH = 4.5 for both materials fitted the pseudo-second-order model giving the r² of 0.970–0.983 and the χ² of 0.008–0.005 and at pH = 6.5 only for C with the r² of 0.986 and the χ² of 0.013. Meanwhile, the adsorption isotherm data at pH = 4.5 for both materials and 6.5 for CFA complied with the Freundlich model (r² > 0.965 and χ² < 0.012), suggesting that NH₄⁺ adsorption onto both adsorbents at those pH values occurred through the formation of a multilayer adsorption on heterogeneous surfaces. This indicates that the dominant adsorption of both adsorbents was physisorption with no site-specific interaction. Based on these results, CFA is proposed as a promising and economical material for the removal of NH₄⁺ from aqueous systems. Full article