Search Results (79)

Accurate prediction of soil phosphorus (P) adsorption capacity is essential for efficient fertilizer management and environmental protection. Traditional isotherm models, such as the Langmuir equation, have been widely used to quantify P sorption, but they do not adequately capture the nonlinear and multivariate nature of soil systems. This study evaluates the performance of a multi-output XGBoost regression model trained on laboratory-measured P adsorption data from 147 soils, representing a wide range of textures, pH levels, and CaCO₃ contents. The model was developed to simultaneously predict P adsorption at five different equilibrium concentrations (1, 2, 4, 6, and 10 mg/L). SHAP analysis and causal discovery via DirectLiNGAM revealed that initial Olsen P concentration and sand content are the primary factors reducing P adsorption. The multi-output XGBoost model was compared against classical Langmuir isotherms using an extended dataset of 10,389 soil samples. The extended dataset was binned into four groups based on Olsen P concentrations and four groups based on sand content. This binning was based on the identification of these variables as highly influential by the XGBoost model, and on their demonstrated causal relationship with soil P sorption capacity through causal inference analysis. The XGBoost model outperformed the Langmuir model in capturing the effect of Olsen P and sand content, as it predicted a 12.6% drop in P adsorption in the very high Olsen P group and a 19.2% drop in the very high sand content groups, which are substantially higher than the reductions estimated by Langmuir isotherms. These results demonstrate that machine learning models, trained on well-designed experimental data, offer a superior alternative to classical isotherms for modeling P sorption dynamics. Full article

Porous CaCO₃ vaterite particles have been widely used as drug carriers for biomedical applications due to their high biocompatibility and low production costs. However, controlling the particle size and porosity of CaCO₃ nanoparticles with the desired crystalline phase is still challenging. In this study, we have systematically investigated the preparation of CaCO₃ nanoparticles under various conditions including precursor types/ratios/concentrations, additive concentrations (ethylene glycol), and temperatures. The materials were fully characterized by optical microscopy, scanning and transmission electron microscopy, infrared spectroscopy, powder X-ray diffraction, dynamic laser scattering, thermogravimetric analysis, and gas sorption. The impacts of the reaction parameters were rationalized and the mechanism for the formation of porous vaterite particles was suggested. It was possible to produce porous vaterite nanoparticles (200 nm) under the optimized conditions, which were further used as drug carrier to upload a model drug curcumin. The potential of using these vaterite particles for controlled drug release was demonstrated. Full article

In this study, we present a comprehensive theoretical analysis of modifications in the physical and chemical properties of MoSe₂ upon the introduction of substitutional transition metal impurities, specifically, Ti, V, Cr, Fe, Co, Ni, Cu, W, Pd, and Pt. Wet systematically calculated the adsorption enthalpies for various representative analytes, including O₂, H₂, CO, CO₂, H₂O, NO₂, formaldehyde, and ethanol, and further evaluated their free energies across a range of temperatures. By employing the formula for probabilities, we accounted for the competition among molecules for active adsorption sites during simultaneous adsorption events. Our findings underscore the importance of integrating temperature effects and competitive adsorption dynamics to predict the performance of highly selective sensors accurately. Additionally, we investigated the influence of temperature and analyte concentration on sensor performance by analyzing the saturation of active sites for specific scenarios using Langmuir sorption theory. Building on our calculated adsorption energies, we screened the catalytic potential of doped MoSe₂ for CO₂-to-methanol conversion reactions. This paper also examines the correlations between the electronic structure of active sites and their associated sensing and catalytic capabilities, offering insights that can inform the design of advanced materials for sensors and catalytic applications. Full article

This work presents the recent development of a fiber-coupled multipass near-infrared (NIR) gas sensor used to monitor water vapor desorption of small material coupons. The gas sensor design employs a White cell topology to maximize the optical path length over a compact, hand-size footprint. Water vapor concentrations are quantified over a large dynamic range by simultaneously applying wavelength modulation and tunable diode laser absorption spectroscopy techniques. A custom headspace optimized for material desorption experiments is assembled using commercially available vacuum chamber components. We provide in situ measurements of water vapor desorption from two geometries of the industrially important silicone elastomer Sylgard-184 as a case study for sensor viability. To corroborate the results, the gas sensor data are compared to numerical simulations based on a triple-mode diffusion–sorption model, consisting of Henry, Langmuir, and Pooling modes. Full article

This review reports some aspects of soil contaminant chemistry and its fundamental role in shaping the soil–human health relationship. Exposure to soil contaminants can occur through direct pathways, such as ingestion, inhalation, and dermal contact, as well as indirect pathways, including food chain contamination via plant uptake or groundwater leaching. The mobility and persistence of organic and inorganic pollutants in soil are primarily controlled by sorption–desorption processes, which involve a complex interplay of physical and chemical mechanisms. Soil properties, such as pH, organic matter content, clay minerals, and oxide hydroxides, play a crucial role in regulating these processes and determining contaminant behavior. A high sorption capacity enhances the soil’s ability to mitigate pollutant mobility, thereby reducing their infiltration into groundwater and accumulation in the food chain. Soils rich in organic matter and fine-textured minerals, such as clay, can effectively immobilize contaminants, limiting their bioavailability and potential harm to human health. A deeper understanding of how soil characteristics influence contaminant mobility and bioavailability is critical to addressing the hazards of soil pollution for human health. Beyond merely assessing contaminant concentrations, it is essential to consider the dynamic processes governing pollutant fate in soil, as they ultimately shape exposure pathways and health risks. This knowledge is the key to developing more effective strategies for mitigating soil contamination and protecting public health. Full article

Seasonal variability significantly influences the fate and transport of antibiotics (Abs) in wastewater stabilization ponds by affecting their concentration, degradation kinetics, sorption behavior, and ecological interactions. This study investigated the influence of seasonal variability for a large number of Ab classes—eleven sulfonamides (SAs), eight fluoroquinolones (FQs), five macrolides (MLs), one diaminopyrimidine (DIA), two tetracyclines (TETs), two lincosamides (LICs), and three phenicols (Phens)—on their fate and transport in an artificial stabilization pond system (SPS) receiving treated WWTP effluent. Two sampling campaigns were conducted during China’s long-lasting seasons (summer and winter). The detection frequency for sulfamethoxazole (SMX), sulfapyridine (SPY), and ofloxacin (OFX) was 100%, for sulfamethazine (SMZ) 63.3%, and for clindamycin (CLN) 83.3% in both seasons. The detection frequency for the other Abs was equal or below 50% in both seasons. In addition, the maximum concentration of SMX, SMZ, SPY, OFX, and CLN in summer was 10.51, 19.37, 6.93, 22, and 4.04 ng/L, respectively, and 4.27, 0.14, 3.15, 9.29, and 8.78, respectively, in winter). The rest of the Abs were either detected in summer or winter. It was observed that environmental fluctuations (such as temperature, precipitation, SPS flow patterns, light intensity), differences in antibiotic use and consumption between seasons, and differences in physicochemical properties of the Abs were the main factors influencing their fate and transport within the SPS. The potential environmental risks of Abs detected in the SPS were assessed using the risk quotient (RQ) approach. Typically, RQs in summer were remarkably higher than in winter. Norfloxacin and chlortetracycline posed a medium risk in summer; however, ofloxacin posed a medium risk in winter and a high risk in summer. Therefore, management strategies should consider the dynamic nature of antibiotic contamination, accounting for seasonal influences on fate and transport within the studied SPS and maybe for other wastewater stabilization ponds by adjusting operational practices, optimizing treatment processes, and implementing source control measures to mitigate the environmental impacts of seasonal antibiotic variability. Full article

This research aims to understand the experimental results on the high selectivity of Pb²⁺ removal over Cd²⁺ in natural and dealuminated rich-clinoptilolite. For this purpose, we have considered the results of experimental and Density Functional Theory (DFT)-based simulated annealing (SA) on sorption of Pb²⁺ and Cd²⁺ from aqueous solution. The dealumination process of natural clinoptilolite (Nat-CLI) was done by H₂SO₄ solutions at different concentrations (0.1–1.0 M). The results show that the maximum sorption capacity (q_,max) of Pb²⁺ and Cd²⁺ varied from 224.554 × 10⁻³ to 53.827 × 10⁻³ meq/g, and between 39.044 × 10⁻³ to 20.529 × 10⁻³ meq/g, respectively, when the values of Si/Al ratio change from 4.36 to 9.50. From a theoretical point of view, the global minimum energies of natural and dealuminated clinoptilolites before and after sorption of Pb²⁺ and Cd²⁺ were calculated by an SA method, where heating-cooling cycles were modeled by ab initio Molecular Dynamics followed by energy minimization. The theoretical results confirmed that for all Si/Al ratios, the sorption of Pb²⁺ and Cd²⁺ takes place, and for dealuminated systems, the exchange energy outcomes are more favorable for the Pb²⁺ cations. Since such energy differences are very small, it is not explained from a thermodynamic point of view. On the other hand, it could be understood from a kinetic perspective. In this way, we set that the atomic structural properties of the zeolite modify the first hydration coordination sphere of metal cations. Full article

This study aimed to investigate the effect of dip coating and the composition of the applied coating on the structure and sorption properties of freeze-dried carrot bars. The scope of the work included preparing freeze-dried carrot bars, coating them with coatings of different gelatin concentrations, and then analysing the sorption properties based on sorption isotherms. Additionally, the structure was assessed based on porosity, shrinkage, and microscopic observations. Water activity and dry matter content were also measured. Analysis of the obtained results showed that coating caused a significant increase in water activity and a decrease in the dry matter content of freeze-dried carrot bars. There was also a decrease in porosity and volume compared to the control sample, which was confirmed by microscopic analysis. The study of sorption kinetics showed that the coatings limited the hygroscopicity of the samples, reducing the dynamics of moisture adsorption and accelerating the stabilisation of water content. The best model describing the sorption isotherms was the Peleg model, and the isotherms themselves were classified as type IIb according to the Blahovec and Yanniotis classification. The composition of the coating significantly affects the structure and selected physical properties of the bars. FT-IR analysis did not show any significant changes in the bars’ chemical structure. Full article

Irbesartan (IRB) is a commonly used BCS Class II antihypertensive drug requiring dissolving capacity enhancement to address oral bioavailability limitations. In this work, seven new IRB salts were successfully synthesized, including one carboxylate (IRB-MAL) and six sulfonate salts (IRB-TOSA, IRB-BSA, IRB-4-CBSA, IRB-2, 5-CBSA, IRB-MSA, and IRB-CPSA). Their vitro dissolution, intrinsic dissolution rates (IDRs), thermal/hygroscopic stability (via thermal analysis, dynamic vapor sorption, and accelerated stability tests), and phase transition process (monitored by in situ Raman spectroscopy) were evaluated. The results revealed that IRB-TOSA, IRB-MAL, IRB-BSA, IRB-4-CBSA, and IRB-MSA salts exhibited IDRs of 0.3194–0.7383 mg/(cm²·min), all significantly higher than IRB, with dissolution concentrations increased by 14.9–113.6%. IRB-TOSA and IRB-4-CBSA salts demonstrated excellent hydrothermal stability. Single crystal structure analysis confirmed proton transfer from coformers’ sulfonic/carboxylic acids (deprotonation site, H-out) to IRB’s diazaheterocycles (protonation site, H-in) in IRB salts. Six sulfonate salts exhibited N_H-in–H···O_H-out and N_non-H-in–H···O_H-out hydrogen bonds, with the former absent in IRB-MAL. Furthermore, supramolecular synthon studies revealed distinct hydrogen-bonding patterns (e.g., bifurcated bonds in 2,5-CBSA and CPSA salts) that correlate with moisture resistance. Quantitative analysis of IRB salts suggested hydrogen bond strengths may influence their melting points (decomposition temperatures). This study demonstrates that IRB salts hold promise for advanced pharmaceutical applications. Full article

Dehydration is the principal conservation process for waterlogged archaeological wood (WAW), with the aim of preventing shrinkage and cracking. For well-preserved WAW, shrinkage mainly takes place when the moisture content is below the fiber saturation point. Here, we conduct a new trial using ionic liquid as a dimensional stabilizer to maintain a stable swollen state of WAW. Molecular dynamics simulation (MD), shrinkage measurement, Fourier transform infrared spectroscopy (FTIR), and dynamic vapor sorption (DVS) were adopted to investigate the interactions and effects of 1-Butyl-3-methylimidazolium chloride ([Bmim][Cl]) on WAW (Dipterocarpaceae Dipterocarpus sp. with a maximum moisture content of 80.3%) in comparison with the conventional material polyethylene glycol (PEG). The results show that [Bmim][Cl] and its water mixtures have a comparable or slightly greater ability to swell amorphous cellulose than does water at room temperature, while crystalline cellulose is left intact. The samples treated with [Bmim][Cl] show less shrinkage than the PEG 300- and PEG 2000-treated samples at all tested concentrations after air-drying. The best dimension control was achieved by 40 wt% [Bmim][Cl], with volumetric shrinkage reduced from 5.03% to 0.47%. DVS analysis reveals that [Bmim][Cl] reduces moisture contents at moderate and low relative humidity (<80%) when the concentration is at or below 20 wt%, which suggests that good dimensional stability was not achieved by simply preserving the moisture content but possibly through the interaction of the ionic liquid with the wood polymers. Full article

With an output of more than two million tons of alumina per year, Venezuela is an important producer. As observed, this mining extraction activity generates a large number of by-products poorly valorized for many reasons (economic, technical, and due to environmental standards and regulations) Venezuela production generates wastes (more than 15 million of m³) called red muds, which are dumped in old lagoons near the Orinoco river or stored. This sludge has a high alkalinity (pH between 10 and 13) and a chemical composition containing some heavy metals (40 ppm Cr, 107 ppm La, 178 ppm Ce) that means it is considered environmentally problematic waste. However, their mineralogical, textural and structural characteristics make them adsorption materials. So, the aim of the study presented here was to investigate the sorption properties of these residues in the case of treatment of water from acid mine drainage. In fact, with an important reactive surface, their capacities to trap by adsorption trace elements such as cadmium, lead or zinc has been studied. Batch sorption tests revealed significant retention of contaminants such as Pb, Zn and As. These retention processes were interpreted using the Langmuir isotherm model. The promising first results indicate that the red mud named Venezuelan bauxite residue (VBR) reveals its great potential as a sorbent of inorganic pollutants. The sorption process is chemically dependent and efficient for certain pH and IS ranges. In addition, the material showed a strong affinity for the adsorption of arsenate (As⁵⁺). This was observed during post adsorption chemical speciation experiments, through the very high affinity of this element for the least mobile fractions, including oxyhydroxides mobile fractions, including Fe oxyhydroxides (amorphous). Nevertheless, these mining by-products could be considered as valuable absorbent materials. Despite this promising results, further studies are required to evaluate their potential in different conditions (dynamic tests, pH, IS, inorganic and organic contaminants, concentration and time effect). Full article

4-Acylpyrazolones are important ligands in analytical chemistry and technologies used for the separation and concentration of various metals. We have proposed a novel method for obtaining a material that consists of covalently immobilized functionalized ionic liquid on the surface of a mineral carrier featuring a coordination-active fragment of 4-acylpyrazolone. For its synthesis, we have introduced a strategy based on the quaternization of surface azolyl groups from 3-(1H-imidazol-1-yl)propyl silica with an alkylating reagent containing a 4-acylpyrazolone motif-4-(6-bromohexanoyl)-5-methyl-2-phenyl-2,4-dihydro-3H-pyrazol-3-one. This method of covalent immobilization preserves the 1,3-dioxo fragment, which ensures the effective binding of metal ions. The success of this functionalization has been confirmed by IR and ¹³C NMR spectroscopy data, as well as by thermogravimetric analysis. The overall functional capacity was found to be 0.3 mmol/g. The potential of the synthesized organomineral material to concentrate five rare earth elements (REEs) representing the cerium (Eu(III), Sm(III)) and yttrium groups (Gd(III), Dy(III), Er(III)) has been demonstrated. It was shown that during extraction from multicomponent systems, both under static and dynamic preconcentration conditions, there is a competitive influence of analytes, and their separation can be evaluated under dynamic conditions based on dynamic output curves and calculated distribution coefficients. It was shown that for systems where Kd > 1.8, quantitative separation can be performed in a dynamic mode of sorption under selected conditions. Full article

Under varying flow rate conditions, the transport and retention of polydisperse microplastics (MPls), with an average particle size of 16 ± 6 µm, were investigated in saturated porous media. First-order reversible and irreversible kinetic sorption models were used to describe the sorption kinetics. Sensitivity analyses provided insight into the effects of each sorption parameter. Both numerical modeling and experimental measurements were utilized to evaluate the retention rates of sand filters. The influence of flow rate on sorption was reflected in variations in the distribution coefficient (K_d), the mass transfer coefficient (β), and the irreversible sorption rate (K₁). Lower flow rates were associated with higher K_d and β values, indicating increased sorption and reduced mass transfer rates. An increase in K_d resulted in a more gradual sorption process, with a decrease in peak concentration, whereas changes in β had a comparatively smaller impact on sorption rate and peak concentration. Lower K₁ values were linked to higher peak concentrations and decreased retention efficiency. Numerical modeling revealed retention rates of 28 ± 1% at a flow rate of 31 mL min⁻¹ and 17 ± 1% at 65 mL min⁻¹. The introduction of MPls into saturated sand environments modifies the transport dynamics within the medium. Consequently, these alterations affect the hydrological characteristics of porous media, impacting groundwater quality and agricultural output. The mean absolute error (MAE) of 6% between the modeled and observed retention rates indicated a high level of accuracy. This study underscores the importance of examining retention efficiency and the accuracy of numerical models in understanding MPl transport in porous media. Full article

One of the key environmental problems underlying climate change and global warming is the persistent increase in atmospheric carbon dioxide concentration. Carbon capture and storage (CCS) systems can be based on, among others, solid porous sorbents (e.g., zeolites). A promising alternative to traditionally used sorbents may be appropriately structured hybrid adsorbents. With the proper geometry and synergistic combination of the sorbent with another material, e.g., a catalyst or a substance with certain useful physical features, they can gain new properties. The present study examined the dynamics of CO₂ sorption in core–shell particles and, as a reference, in particles with a uniform structure. It was assumed that the sorbent (zeolite 5A) incorporated in a single particle had the form of microcrystals, which implies a bidisperse particle structure. As a second particle-forming material, a nickel catalyst (behaving as an inert) was adopted. The computational results confirmed that particle structure can provide an additional design parameter for adsorption columns and adsorptive reactors. The sorption-inactive shell proved to play a protective role when thermal waves moved through the bed. In addition, an important element determining sorption dynamics in core–shell particles was revealed to be the structure (e.g., mean pore diameter) controlling intraparticle mass transport. Full article

This study investigates the applicability of the Peleg model to the osmotic dehydration of various sweet potato variety samples in sugar beet molasses, addressing a notable gap in the existing literature. The osmotic dehydration was performed using an 80% sugar beet molasses solution at temperatures of 20 °C, 35 °C, and 50 °C for periods of 1, 3, and 5 h. The sample-to-solution ratio was 1:5. The objectives encompassed evaluating the Peleg equation’s suitability for modeling mass transfer during osmotic dehydration and determining equilibrium water and solid contents at various temperatures. With its modified equation, the Peleg model accurately described water loss and solid gain dynamics during osmotic treatment, as evidenced by a high coefficient of determination value (r²) ranging from 0.990 to 1.000. Analysis of Peleg constants revealed temperature and concentration dependencies, aligning with previous observations. The Guggenheim, Anderson, and de Boer (GAB) model was employed to characterize sorption isotherms, yielding coefficients comparable to prior studies. Effective moisture diffusivity and activation energy calculations further elucidated the drying kinetics, with effective moisture diffusivity values ranging from 1.85 × 10⁻⁸ to 4.83 × 10⁻⁸ m²/s and activation energy between 7.096 and 16.652 kJ/mol. These findings contribute to understanding the complex kinetics of osmotic dehydration and provide insights into the modeling and optimization of dehydration processes for sweet potato samples, with implications for food processing and preservation methodologies. Full article