Adsorption最新文献

In this work, we investigate the structural parameters that affect water adsorption on amorphous carbon nitride thin films synthesized by pulsed laser deposition. The study includes the case of ablation of graphite targets within molecular nitrogen and within a stream of nitrogen plasma afterglow. The results obtained showed that, the effect of Csp²-Csp² bonds concentration on the adsorption of water molecules depends strongly on the ratio and distortion of the hexagonal rings. Furthermore, analysis of the spectral data showed that, the relationship between the hydrogen bonding strength of water molecules with the film surface and the concentration of Csp²-Csp² bonds takes a specific mathematical formula in the case of structures composed mainly of hexagonal rings.

Capturing CF₄ is crucial for mitigating its substantial greenhouse effect and environmental impact in the microelectronics industry. Here we employed a hybrid approach combining grand canonical ensemble Monte Carlo molecular simulations and neural network models to screen over 100 amorphous materials for N₂/CF₄ gas adsorption storage and separation. Materials with higher adsorption capacities exhibited densities around 0.7 to 1.0 g/cm³ and pore sizes within the range of 1.4–1.6 Å. At 298 K and 1000 kPa, HCP-Colina-id0016 and aCarbon-Bhatia-id001 demonstrated the highest CF₄ adsorption, reaching 5.65 and 5.34 mmol/g, respectively. For the separation of N₂/CF₄ mixtures, considering the comprehensive CF₄ adsorption selectivity and capacity, we recommend HCP-Colina-id0016 at high pressure conditions (4500 kPa) and aCarbon-Bhatia-id001 at medium to low pressures (below 500 kPa). The separation of mixtures is more favorable at low CF₄ concentrations, becoming more challenging as CF₄ concentration increases. Additionally, the Ideal Adsorbed Solution Theory (IAST) accurately predicted the separation of the N₂/CF₄ system on amorphous materials. We found that the genetic algorithm-optimized neural network (GA-BP) outperformed the standalone backpropagation neural network (BP) in accurately predicting the relationship between material structural properties and CF₄ adsorption, showing its potential for widespread application in large-scale material screening.

Tetracyclines (TCs) constitute a group of antibiotics that are commonly used to treat bacterial diseases, in veterinary medicine and as an additive in animal feed. This broad application has led to their accumulation in food products and the environment because sewage treatment plants cannot completely remove them. Therefore, the aim of this study was to synthesize graphene oxide (GO) and evaluate its TC adsorption properties in aqueous media. The effects of pH (between 2.5 and 11) and Ca²⁺ concentration (between 0 and 1 M) were thoroughly investigated. Structural, textural, and electrokinetic properties of the prepared GO were determined by N₂ adsorption/desorption, XRD, TEM, UV–vis, FTIR, XPS, thermogravimetry and electrophoretic mobility measurements. TC adsorption on GO is an interplay between the two main roles played by Ca²⁺: competitor or bridging cation. At low pH, there is cation exchange, and Ca²⁺ behaves as a competitor of the positively charged TC species, decreasing adsorption as calcium concentration increases. At high, the formation of Ca bridges between the surface and TC (GO-Ca²⁺-TC) is favored, increasing the adsorption of the antibiotic by increasing calcium concentration. Different combinations of Ca²⁺ and pH effects are important to improve the use of GO either as a pH-dependent and reversible TC adsorbent for decontamination or as pH-independent adsorbent for TC quantification with electrochemical sensors.

This study investigates the sensitivity and selectivity of gas adsorption (SF₆, SO₂F₂, SOF₂, SO₂, and HF) on SiGe surfaces and Ca atom-decorated SiGe surfaces using Density Functional Theory (DFT). The optimized structures, bond lengths, and angles of the gas molecules are analyzed, providing valuable insights into their geometric features and bonding configurations. For every gas on both surfaces, important variables such as adsorption energy, and charge transfer are examined. In particular, there is a significant increase in charge transfer and adsorption energy when SF₆ interacts with Ca$2D-SiGe as opposed to the SiGe surface. To emphasize changes in band gap and electronic structure, the study explores electronic properties such as density of states (DOS) and projected density of states (PDOS) spectra before and after gas adsorption. Electron density differences (EDD) analysis is used to clarify the type of interactions, including accumulation and depletion of charge. The results reveal that all gases except HF/ Ca$2D-SiGe showed chemical adsorption. The study also takes into account recovery time, an important metric for sensor materials, which is calculated for the breakdown gases of SF₆ on both surfaces at different temperatures and shows potential uses for gas detection. Future research should focus on a broader range of gas molecules and their interactions with SiGe and Ca-decorated SiGe surfaces. Ultimately, the integration of SiGe-based sensor devices in real-world applications such as environmental monitoring, industrial safety, and medical diagnostics can be explored to understand the broader potential of these materials in the field of gas detection.

Activated carbon (AC) has recently gained increasing attention for removing various contaminants from water. AC obtained by agroindustrial waste is considered one of the essential adsorbent materials, which plays a vital role in processes of adsorption in water purification and wastewater treatment. Given the extensive use of this material, it is essential to understand its entire production chain and environmental impact. In this work, banana peel waste (BPF) was submitted at NaOH activation followed by pyrolysis at 600 °C to produce activated biochar (BFAC), aiming to remove methylene blue (MB) from wastewater. BFAC was characterized by TGA, XRD, SEM, BET, and FTIR techniques. The influence of dye concentration (10, 25, 50, 100, 250, and 500 mg L^− 1) and zero point charge (ZPC) were investigated. Besides, a Life Cycle Assessment (LCA) was carried out to assess the environmental impacts of the developed process. BFAC presented a well-developed pore structure with a predominance of mesopores and macropores, which directly influenced the MB removal capacity. The highest efficiency for dye removal was 62% after 10 min to an initial concentration of 50 mg.L^-1. The adsorption isotherms were well defined by Langmuir, Freundlich, and Temkin isotherm models. The Langmuir model represented the best fit of experimental data for BFAC with a maximum adsorption capacity of 49.5 mg g^− 1. Regarding LCA, a prospective approach at the early stage of development was conducted to orient the transition from laboratory to industrial scale, aiming at providing a competitive CO₂-based technological route. The scenarios proposed suggest that this route is promising either from the life cycle assessment or the circular economy perspective. Thus, BFAC can be considered an adsorbent with great practical application for post-treatment wastewater effluents to remove contaminants.

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To anchor chelating groups with nitrogen and sulfur atoms on tannin, a novel adsorbent (tannin-thiosemicarbazide-formaldehyde resin) was prepared through Mannich reaction by using blank wattle tannin, thiosemicarbazide and formaldehyde as raw materials. The adsorption behaviour of Ag⁺ from aqueous solution on the resin was evaluated via batch adsorption experiments. Fourier transform infrared spectroscopy (FT–IR) and elemental analysis were applied to verify the successful immobilization. The surface morphology, thermal stability and pore structure of the resin were also characterized. The results showed that the adsorption isotherm of Ag⁺ for the resin was described well by the Freundlich model. Ag⁺ adsorption equilibrium was achieved within 180 min, and the kinetic data were better fitted by the pseudo-second-order kinetic equation than by the pseudo-first-order and intraparticle diffusion equations. The adsorption capacity first increased and then stabilized with increasing pH (ranging from 1.0 to 7.0), and the resin exhibited high selectivity towards Ag⁺ in relation to Pb²⁺, Cd²⁺, Ni²⁺ and Ca²⁺. After three regeneration and reuse cycles, the adsorption capacity reached 1.68 mmol/g (84.0% of removal efficiency). Based on the experimental results and findings from various characterization techniques, the mechanism of Ag⁺ adsorption onto the resin could be attributed to inner-sphere complexation and chelation between Ag⁺ and multiple electron-rich atoms ( N, O, and S), in which S atoms played the most important role.

This study presents the use of jabuticaba peel to create a biosorbent material for recovering cyanidin-3-glucoside (C3G), a valuable compound in anthocyanin-rich extracts. This approach tackles waste management, promotes a circular economy, and offers a sustainable alternative to traditional methods. The biosorbents were synthesized through a chemical activation using three different solvents: H₃PO₄, HNO₃, and KOH. Sample characterization was conducted through various techniques, providing a thorough and multi-faceted understanding of the material properties. The morphological results showed the development of rich porous structures and increased carbon concentrations after activation, enhancing the adsorption capacity of the synthesized materials derived from jaboticaba peel. The H₃PO₄-activated biosorbent outperformed commercial adsorbents. Granulometric and concentration studies identified optimal conditions, and colorimetric analysis confirmed effective C3G removal. Kinetic studies indicated an adsorption process reaching equilibrium within 9.0 h. The Avrami model suggested a complex adsorption mechanism and intraparticle diffusion, which revealed a two-step process involving external mass transfer and internal diffusion. Adsorption isotherms at different temperatures fit the Langmuir model, indicating favorable adsorption behavior. The thermodynamic analysis confirmed the viability of jabuticaba peel biosorbents for eco-friendly C3G removal due to spontaneous, endothermic adsorption processes. The reuse study demonstrated that the biosorbent maintained its adsorption capacity up to the fifth cycle. Additionally, the adsorption mechanism of C3G on H₃PO₄-activated biosorbent was identified, emphasizing cation-π interaction, pore filling, electrostatic attraction, van der Waals forces, hydrogen bonds, and π-π interactions at pH 2. This revealed a physisorption process with diverse intermolecular forces. This study further supports ecological waste management and the creation of economical biosorbents for anthocyanin recovery, valuable compounds applicable in pharmaceuticals, food, and nutraceutical industries.

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