Search Results (132)

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

The competitive retention of pollutants in water tables determines their environmental fate and guides routes for their removal. To distinguish the fine differences in competitive binding at zeolite adsorption centers, a group of neonicotinoid pesticides is compared, relying on theoretical (energy of adsorption, orientation, charge distribution) and experimental (spectroscopic and thermogravimetric) analyses for quick, inexpensive, and reliable screening. The MOPAC/QuantumEspresso platform was used for theoretical calculation, indicating close adsorption energy values for acetamiprid and imidacloprid (−2.2 eV), with thiamethoxam having a lower binding energy of −1.7 eV. FTIR analysis confirmed hydrogen bonding, among different dipole-dipole interactions, as the dominant adsorption mechanism. Due to their comparable binding energies, when the mixture of all three pesticides is examined, comparative adsorption capacities are evident at low concentrations, owing to the excellent adsorption performance of the FAU zeotype. At higher concentrations, competition for adsorption centers occurs, with the expected thiamethoxam binding being diminished due to the lower bonding energy. The catalytic impact of zeolite on the thermal degradation of pesticides is evidenced through TG analysis, confirming the adsorption capacities found by UV/VIS and HPLC/UV measurements. Detailed analysis of spectroscopic results in conjunction with theoretical calculation, thermal profiles, and UV detection offers a comprehensive understanding of neonicotinoids’ adsorption and can help with the design of future adsorbents. Full article

Divinylisoprene rubber, a copolymer of butadiene and isoprene, is used as raw material for rubber technical products, combining isoprene rubber’s elasticity and butadiene rubber’s wear resistance. These properties depend quantitatively on the copolymer composition, which depends on the kinetics of its synthesis. This work aims to theoretically describe how the monomer mixture composition in the butadiene–isoprene copolymerization affects the activity of the TiCl₄-Al(i-C₄H₉)₃ catalytic system (expressed by active sites concentration) via kinetic modeling. This enables development of a reliable kinetic model for divinylisoprene rubber synthesis, predicting reaction rate, molecular weight, and composition, applicable to reactor design and process intensification. Active sites concentrations were calculated from experimental copolymerization rates and known chain propagation constants for various monomer compositions. Kinetic equations for active sites formation were based on mass-action law and Langmuir monomolecular adsorption theory. An analytical equation relating active sites concentration to monomer composition was derived, analyzed, and optimized with experimental data. The results show that monomer composition’s influence on active sites concentration is well described by a two-step kinetic model (physical adsorption followed by Ti–C bond formation), accounting for competitive adsorption: isoprene adsorbs more readily, while butadiene forms more stable active sites. Full article

This study presents the synthesis, characterization, and application of magnetic magnetite–zirconium dioxide (Fe₃O₄–ZrO₂) nanoparticles as an efficient nanoadsorbent for fluoride removal from water. The nanoparticles were synthesized using a wet chemical co-precipitation method with Fe/Zr molar ratios of 1:1, 1:2, and 1:4, and characterized using Fourier-transform infrared (FTIR) spectroscopy, scanning electron microscopy (SEM), X-ray diffraction (XRD), and energy-dispersive X-ray spectroscopy (EDS). FTIR analysis confirmed the presence of Fe₃O₄ and ZrO₂ functional groups, while XRD showed that increased Zr content led to a dominant amorphous phase. SEM and EDS analyses revealed quasi-spherical and elongated morphologies with uniform elemental distribution, maintaining the designed Fe/Zr ratios. Preliminary adsorption tests identified the Fe/Zr = 1:1 (M1) nanoadsorbent as the most effective due to its high surface homogeneity and optimal fluoride-binding characteristics. Adsorption experiments demonstrated that the material achieved a maximum fluoride adsorption capacity of 70.4 mg/g at pH 3, with the adsorption process best fitting the Temkin isotherm model (R² = 0.987), suggesting strong adsorbate–adsorbent interactions. pH-dependent studies confirmed that adsorption efficiency decreased at higher pH values due to electrostatic repulsion and competition with hydroxyl ions. Competitive ion experiments revealed that common anions such as nitrate, chloride, and sulfate had negligible effects on fluoride adsorption, whereas bicarbonate, carbonate, and phosphate reduced removal efficiency due to their strong interactions with active adsorption sites. The Fe₃O₄–ZrO₂ nanoadsorbent exhibited excellent magnetic properties, facilitating rapid and efficient separation using an external magnetic field, making it a promising candidate for practical water treatment applications. Full article

Zeolite adsorption followed by NaCl-NaClO regeneration is an effective method for the on-site treatment of ammonia in initial stormwater. However, the formation and toxicity of chlorine species during the zeolite regeneration process need to be investigated. In this study, under intermittent and continuous operations, zeolites adsorbed NH₄Cl + HA (humic acid) and actual stormwater, then regenerated with NaCl-NaClO (0.5 g/L NaCl, ClO⁻:N molar ratio of 1.8, pH = 10). This technology was assessed from the following three aspects: adsorption and regeneration, chlorine species formation, and toxicity. The results showed that zeolites exhibited a greater adsorption capacity for HA in stormwater compared to that in an NH4Cl + HA solution, and the presence of ammonia had a minimal impact on this process. During zeolite regeneration, ammonia had a competitive advantage over HA for ClO⁻. ClO₃⁻ was inevitably formed in regeneration. The formation of chlorinated organic compounds (COPs) increased over time. The order of chlorine species toxicity in zeolite regeneration solution was free chlorine > COPs > ClO₃⁻. Controlled regeneration time was required to minimize the formation and toxicity of chlorine species. During the 10 cycles of regeneration, chlorine species continued to form and caused high toxicity hazards. Full article

Levelers are indispensable additives for achieving void-free, bottom-up superconformal copper filling of microvias. Establishing the molecular-level correlation between leveler structure and performance is therefore essential to the continued advancement of microelectronic copper-plating technology. Herein, nitro blue tetrazolium chloride (NBT) is identified as an efficient leveler for copper microvia superfilling. A multiscale strategy—combining electrochemical measurements, X-ray photoelectron spectroscopy (XPS), density functional theory (DFT) calculations, and molecular dynamics (MD) simulations—is employed to elucidate the action mechanism of NBT and pinpoint its electroactive sites. Electrochemical tests show that NBT markedly suppresses copper deposition and, together with polyethylene glycol (PEG), effectively resists competitive adsorption by bis-(3-sulfopropyl) disulfide (SPS), thereby enhancing the microvia superfilling performance of the PEG–SPS–NBT additive system. DFT results reveal that the nitro groups and tetrazolium rings constitute the primary adsorption centers on the copper surface; the nitro groups additionally strengthen intermolecular interactions between NBT and PEG. MD simulations further confirm that NBT anchors onto the Cu(111) surface predominantly through these NO₂ groups and the tetrazolium ring, while co-adsorbed PEG enhances the overall adsorption strength of NBT. The electroplating experiment demonstrates that NBT can act as an effective leveler for microvia superfilling. Moreover, XPS analyses further confirm the synergistic co-adsorption of NBT and PEG and verify that the NO₂ groups and tetrazolium rings are the dominant adsorption sites of NBT. Collectively, the electroplating, XPS, electrochemical, DFT, and MD findings clarify the structure–activity relationship of NBT and provide rational guidelines for designing next-generation copper-plating levelers. Full article

Owing to global energy demands and climate change resulting from fossil fuel use, technologies capable of converting greenhouse gases into renewable energy resources are needed. One such technology is photocatalytic CO₂ reduction, which utilises solar energy to transform CO₂ into value-added hydrocarbons. However, the application of photocatalytic CO₂ reduction is limited by the inefficiency of existing photocatalysts. In this study, we developed a nitrogen-deficient g-C₃N₄-confined PtCu dual-atom catalyst (PtCu/V_N-C₃N₄) for photocatalytic CO₂ reduction. Aberration-corrected high-angle annular dark-field scanning transmission electron microscopy and X-ray absorption fine structure spectroscopy confirmed the atomic-level anchoring of PtCu pairs onto the nitrogen-vacancy-rich g-C₃N₄ nanosheets. The optimised PtCu/V_N-C₃N₄ exhibited superior photocatalytic performance, with CO and CH₄ evolution rates of 13.3 µmol/g/h and 2.5 µmol/g/h, respectively, under visible-light irradiation. Mechanistic investigations revealed that CO₂ molecules were preferentially adsorbed onto the PtCu dual sites, initiating a stepwise reduction pathway. In situ diffuse reflectance infrared Fourier-transform spectroscopy identified the formation of a key intermediate (HCOO*), whereas interfacial wettability studies demonstrated efficient H₂O adsorption on PtCu sites, providing essential proton sources for CO₂ protonation. Photoelectrochemical characterisation further confirmed the enhanced charge-transfer kinetics in PtCu/V_N-C₃N₄, which were attributed to the synergistic interplay between the nitrogen vacancies and dual-atom sites. Notably, the dual-active-site architecture minimised the competitive adsorption between CO₂ and H₂O molecules, thereby optimising the surface reaction pathways. This study establishes a rational strategy for designing atomically precise dual-atom catalysts through defect engineering, achieving concurrent improvements in activity, selectivity, and charge carrier utilisation for solar-driven CO₂ conversion. Full article

CO₂-enhanced coalbed methane recovery (CO₂-ECBM) represents a promising pathway within carbon capture, utilization, and storage (CCUS) technologies, offering dual benefits of methane production and long-term CO₂ sequestration. This review provides a comprehensive analysis of CO₂-ECBM from a full-chain perspective (Mechanism, Practices, and Outlook), covering fundamental mechanisms and key engineering practices. It highlights the complex multi-physics processes involved, including competitive adsorption–desorption, diffusion and seepage, thermal effects, stress responses, and geochemical interactions. Recent progress in laboratory experiments, capacity assessments, site evaluations, monitoring techniques, and numerical simulations are systematically reviewed. Field studies indicate that CO₂-ECBM performance is strongly influenced by reservoir pressure, temperature, injection rate, and coal seam properties. Structural conditions and multi-field coupling further affect storage efficiency and long-term security. This work also addresses major technical challenges such as real-time monitoring limitations, environmental risks, injection-induced seismicity, and economic constraints. Future research directions emphasize the need to deepen understanding of coupling mechanisms, improve monitoring frameworks, and advance integrated engineering optimization. By synthesizing recent advances and identifying research priorities, this review aims to provide theoretical support and practical guidance for the scalable deployment of CO₂-ECBM, contributing to global energy transition and carbon neutrality goals. Full article

The excessive input of nitrogen and phosphorus pollutants into surface water bodies poses a serious threat to the aquatic ecosystem. As an efficient porous adsorbent material, ceramsite shows remarkable potential in the field of simultaneous nitrogen and phosphorus removal. In this study, Fe₂O₃ catalyzed the decomposition of K₂CO₃ to generate CO and CO₂ gases, leading to the formation of a large number of pore structures in the composite ceramsite. Subsequently, adsorption experiments were conducted on the obtained ceramsite. The regulatory mechanisms of the ceramsite dosage and solution pH on its adsorption performance were revealed. The experiments show that as the ceramsite dosage increased from 2.1 g/L to 9.6 g/L, the adsorption capacities of ammonia–nitrogen and phosphorus decreased from 0.4521 mg/g and 0.4280 mg/g to 0.1430 mg/g and 0.1819 mg/g, respectively, while the removal rates increased to 68.66% and 58.22%, respectively. This indicates that the competition between the utilization efficiency of adsorption sites and the mass-transfer limitation between particles dominates this process. An analysis of the pH effect reveals that the adsorption of ammonia–nitrogen reached a peak at pH = 10 (adsorption capacity of 0.4429 mg/g and removal rate of 81.58%), while the optimal adsorption of phosphorus occurred at pH = 7 (adsorption capacity of 0.3446 mg/g and removal rate of 86.40%). This phenomenon is closely related to the interaction between the existing forms of pollutants and the surface charge. Kinetic and thermodynamic studies show that the pseudo-second-order kinetic model (R² > 0.99) and the Langmuir isothermal model can accurately describe the adsorption behavior of the ceramsite for ammonia–nitrogen and phosphorus, confirming that the adsorption is dominated by a monolayer chemical adsorption mechanism. This study explores the dosage–efficiency relationship and pH response mechanism of Fe₂O₃-catalyzed porous ceramsite for nitrogen and phosphorus adsorption, revealing the interface reaction pathway dominated by Fe₂O₃ catalysis and chemical adsorption. It provides theoretical support for the construction of porous ceramsite and the development of an efficient technology system for the synergistic removal of nitrogen and phosphorus. Full article

With the worsening global water pollution crisis, pharmaceuticals and personal care products (PPCPs) have been increasingly detected in aquatic environments. The effective removal of PPCPs remains challenging for conventional water treatment technologies, whereas photocatalytic technology has shown distinct promise. Dissolved organic matter (DOM), a ubiquitous component of aquatic ecosystems, exerts multifaceted effects on the photocatalytic oxidation of PPCPs. In this article, the influence of DOM on the performance of various photocatalysts in PPCP removal is systematically summarized and analyzed. This review highlights DOM’s role in altering the migration and transformation of PPCPs via processes including adsorption and complexation. The adsorption of PPCPs on photocatalysts is achieved by competitive adsorption or by providing more adsorption sites. DOM modifies the structural properties of photocatalysts through mechanisms such as ligand exchange, intermolecular forces, electrostatic forces, and hydrophobic interactions. DOM inhibits the formation of active species via light attenuation and shielding effects while simultaneously enhancing their generation through photosensitization and electron transfer facilitation. In this review, the interaction mechanism among DOM, PPCPs, and photocatalysts within the PPCP photocatalytic oxidation system is expounded on. These findings provide novel insights into optimizing photocatalytic reaction conditions and enhancing treatment efficiency, while providing a theoretical foundation for advancing efficient, eco-friendly PPCPs remediation technologies. Full article

This study presents a novel ion-imprinted fiber material, I-(PP-g-GMA-NMDG), designed for the rapid and selective adsorption of borate ions. Leveraging low-temperature plasma graft polymerization, polypropylene (PP) melt-blown fibers were functionalized with glycidyl methacrylate (GMA) and N-methyl-D-glucamine (NMDG) to introduce tailored recognition sites. Systematic optimization of plasma parameters (100 W discharge power, O₂ atmosphere) and liquid-phase grafting conditions (28.5% GMA, 85 °C, 2.5 h) achieved a grafting rate of 203.26%. The imprinted fibers exhibited exceptional adsorption performance, with a maximum capacity of 35.85 mg/g at pH 9, reaching 90% saturation within 60 min. Adsorption kinetics adhered to a pseudo-second-order model, while the Freundlich isotherm indicated multilayer adsorption. Competitive ion experiments demonstrated high selectivity for B(OH)₄⁻ over anions (SO₄²⁻ and Cl⁻) and cations (Na⁺, K⁺, Ca²⁺, and Mg²⁺), which was attributed to the precise spatial and charge complementarity of the imprinted cavities. Characterization via FT-IR, XRD, and SEM confirmed successful synthesis and structural stability. The material retained 78.1% adsorption efficiency after five regeneration cycles, showcasing its practicality for boron recovery from wastewater. This work advances boron-selective adsorption technology by combining plasma modification with ion imprinting, offering a sustainable solution for industrial and environmental applications. Full article

The presence of abundant water vapor in industrial organic waste gases greatly reduces the selective adsorption of volatile organic pollutants (VOCs). The polarity of the adsorbent and VOC molecules plays an important role in the adsorption process, especially in the presence of water vapor. In this paper, commercial coconut shell activated carbon (CSC) was modified by a thermal reduction treatment to obtain heat-treated coconut shell activated carbon (HCSC). CSC and HCSC exhibited similar pore structure characteristics but differed significantly in surface oxygen content (10.97% and 7.55%, respectively). Dynamic adsorption breakthrough experiments were conducted to determine the dynamic adsorption capacities of toluene on both adsorbents under varying relative humidity levels. HCSC demonstrated superior toluene/water vapor adsorption selectivity. Further analyses of toluene adsorption kinetics, activation energy, and water vapor adsorption isotherms revealed that the lower surface oxygen functional group content of HCSC resulted in a weaker surface polarity, facilitating the adsorption of weakly polar toluene. This was attributed to stronger toluene–HCSC interactions and weaker water–HCSC interactions. The dynamic adsorption capacities of three VOCs with varying polarities were also tested on HCSC. The observed VOC/water vapor adsorption selectivity had the following order: toluene > n-heptane > 1,2-dichloroethane. Grand Canonical Monte Carlo (GCMC) simulations were employed to quantify the relationship between the adsorption selectivity of eight VOCs with varying polarities and their molecular polarity. The results indicated a decrease in adsorption selectivity with increasing VOC polarity. A mechanistic analysis suggests that more polar VOCs prefer to adsorb polar oxygen-containing functional groups, competing with water molecules for adsorption sites. Under high humidity, hydrogen bonding leads to the formation of water clusters, exacerbating this competition. This research holds significant implications for the efficient selective adsorption of VOCs with varying polarities in humid industrial conditions. Full article

The selective adsorption and separation of benzene from structurally similar six-membered hydrocarbons and fluorocarbons remain a significant challenge due to their comparable physical properties. In this study, we investigated the molecular recognition and separation properties of a perfluorinated triketonate Cu(II) complex (1) as a Nonporous Adaptive Crystal (NAC). In addition to the previously reported benzene (2)-encapsulated crystal of 1•(2)₃, we report here the crystal structures of guest-free 1 and cyclohexene (3)-encapsulated 1•(O)₂•3, where (O)₂ represents two water molecules. Single-crystal analysis demonstrated that 1 selectively encapsulates 2 while excluding other hydrocarbons, including 3, cyclohexane (4), trifluorobenzene (5), and hexafluorobenzene (6). Gas adsorption experiments confirmed this high affinity for 2, as reflected in its preferential adsorption behavior in mixed solvent and vapor environments. The molecular selectivity of 1 was attributed to strong π-hole···π and metal···π interactions, which favor electron-rich aromatic guests. Additionally, crystallization experiments in competitive solvent systems consistently led to the formation of 1•(2)₃, reinforcing the high selectivity of 1 for 2. These findings highlight the unique molecular recognition capabilities of NACs, providing valuable insights into the rational design of advanced molecular separation materials for industrial applications involving aromatic hydrocarbons. Hirshfeld surface analysis revealed that the contribution of F···F interactions to crystal packing decreased upon guest recognition (48.8% in 1, 34.2% in 1•(O)₂•3, and 22.2% in 1•(2)₃), while the contribution of F···H/H···F interactions increased (8.6% in 1, 22.2% in 1•(O)₂•3, and 35.4% in 1•(2)₃). Regarding Cu interactions, the self-assembled columnar structure of 1 results in close contacts at the coordination sites, including Cu···Cu (0.1%), Cu···O (0.7%), and Cu···C (1.3%). However, in the guest-incorporated structures 1•(O)₂•3 and 1•(2)₃, the Cu···Cu contribution disappears; instead, 1•(O)₂•3 exhibits a significant increase in Cu···O interactions (1.2%), corresponding to water coordination, while 1•(2)₃ shows an increase in Cu···C interactions (1.5%), indicative of the metal···π interactions of benzene. Full article

Volatile organic compounds (VOCs) from petrochemical, pharmaceutical, and other industries have serious damage to human health and the environment. Catalytic oxidation is a promising method to eliminate air pollution due to its high efficiency, wide application range, and environmental friendliness. However, in the actual industrial environment, the composition of industrial exhaust gases is complex, including VOCs, water vapour, chloride, sulfide and so on. The impurities would have competitive adsorption with reactants or react with the active sites, leading to the decline of catalytic activity, even the deactivation of catalysts. Therefore, this review summarises the recent research on the anti-poisoning ability of catalysts in the catalytic oxidation of VOCs, primarily focusing on the effect of water vapour, chloride, and sulfide. The catalytic oxidation mechanism manifested that the adsorption and activation of reactants are significant in VOCs degradation. On this basis, the mechanism of catalyst poisoning was analysed, and the inhibitory effect of impurities on the oxidation reaction was elucidated. According to the research status, three anti-poisoning strategies are proposed, including building a bimetallic system, modifying supports, and establishing the protected coating. This work provides a theoretical foundation and reference point for the rational construction of anti-poisoning catalysts in VOCs elimination. Full article

The interactions among water molecules, coal beds, and gases during the process of coal bed methane mining are highly complex. The water and methane (CH₄)/carbon dioxide (CO₂) molecules compete for adsorption and undergo a series of reactions that affect gas diffusion. In this study, Monte Carlo and molecular dynamics methods were used to investigate the microscopic mechanism of CH₄/CO₂ competitive adsorption and diffusion during CO₂-enhanced coal bed methane mining (ECBM) under different moisture contents, and the geological storage potential of CO₂ was predicted. The results showed that when the CO₂ and water binding sites were independent of each other, the water molecules changed the electrostatic potential around the coal molecules, resulting in enhanced CO₂ adsorption performance, as verified by the surface electrostatic potential. When the water molecules formed a water molecule layer, the adsorption capacity of the secondary adsorption sites provided was larger than that of the surface of the coal molecules, so the CO₂ molecules were preferentially adsorbed on the secondary adsorption sites. However, the number of secondary adsorption sites available was not as large as that on the surface of the coal molecules. The interaction energies revealed that when the displacement effect of CH₄ in the process of CO₂-ECBM and the sequestration effect of CO₂ were considered comprehensively, the best CO₂ sequestration effect and a good CH₄ displacement effect were obtained at a 3% moisture content. The worst CO₂ sequestration effect was found at a 5% moisture content. After CO₂ injection, the main adsorption layer of CH₄ shifted from X = 5 and X = 9 to X = 8.7 and X = 12.5, respectively, and obvious detachment and diffusion occurred. The distribution of the molecular motion and diffusion coefficient revealed the considerable displacement and dispersion of the gas molecules. The distribution of the gas molecular velocity and diffusion coefficient indicated that a 3% moisture content was the ideal condition for CO₂ displacement of CH₄, and the CO₂ sequestration effect was good. Full article