Adsorption最新文献

This work explores the sensing capabilities of Cr and Cu modified WS₂ nanosheets in detecting desflurane (C₃H₂F₆O) molecule to search for the most efficient sensing nanomaterials. Adsorption of C₃H₂F₆O molecule on the pristine and Cr/Cu modified WS₂ nanosheets was studied using the density functional theory calculations. Desflurane was adsorbed from both oxygen and Fluorine active sites after the adsorption structures were fully optimized. The relaxed configurations were utilized for calculating geometrical and electronic properties such as adsorption energies, projected density of states and band structures. The negative adsorption energies indicated the stable adsorption of desflurane on the Cr and Cu modified WS₂ nanosheets. The results also indicated that desflurane adsorption did not change the electronic properties of Cr and Cu modified WS₂ considerably, except for some changes in the band gap interval. Based on spin-polarized calculations, both Cr and Cu modified WS₂ monolayers magnetic and semiconducting properties. These findings suggested that Cr and Cu modified WS₂ nanostructures are brilliant candidates for sensing C₃H₂F₆O molecules.

To study the separation of methane and nitrogen mixtures by gas-phase simulated moving bed (SMB), Maxsorb activated carbon was pelletised by extrusion with 10% binder. Both argon and carbon dioxide were used as potential desorbent gases. The effectiveness of the adsorbent was assessed by analysing the adsorption equilibrium data and conducting fixed-bed experiments to determine the single and multicomponent dynamic adsorption behaviour. Pure component N₂, CH₄, Ar, and CO₂ isotherms were measured at three different temperatures, up to 2.5 bar, using a volumetric method. The results show that CO₂ exhibits the highest affinity to the solid phase, followed by CH₄, N_2, and Ar. Single, binary, and ternary fixed-bed experiments were performed, allowing the validation of the proposed mathematical model. Two SMB cycles were designed to separate a CH₄/N₂ mixture using each desorbent gas. The respective separation regions were drawn. Both processes achieved a high purity level for the methane stream (above 99%) and exhibited high recovery (above 97%). The obtained results were crossed with the previously studied BPL material, and the Maxsorb adsorbent showed better performance overall.

The efficient elimination of synthetic dyes from industrial wastewaters continues to be a significant environmental issue. This paper describes one-pot synthesis of zinc titanate nanocomposites exhibiting dual adsorption and photocatalytic properties, achieved using precipitation/calcination and solvothermal techniques from a common precursor solution. Methylene blue (MB), a frequently utilized cationic dye, was chosen as the model contaminant. The zinc titanate composites exhibited significant adsorption capabilities; consistently attaining > 4 mg of MB adsorbed per gram of material for all Zn/Ti ratios within the initial 30 min in the absence of UV light exposure. Composites having a Zn/Ti ratio of 0.5 exhibited superior performance, with Z-0.5c attaining the maximum photocatalytic degradation under UV illumination. Phase analysis indicated that calcination resulted in increased crystallinity, which was associated with improved photocatalytic activity, while solvothermally generated samples preserved nanoscale morphologies that facilitated adsorption. The results underscore the efficacy ofzinc titanate nanocomposites as dual-function materials for wastewater treatment, facilitating fast adsorption and prolonged photocatalytic degradation to enhance dye elimination. This study offers significant insights into the optimization of Zn/Ti ratios and synthesis techniques for improved environmental applications.

In the present study, the capability of Al, Si, P doped and novel TiAl₃ decorated MoS₂ nanosheet for sensing and adsorption of the acrolein molecule has been scrutinized through the periodic density functional theory. The changes in the energy gap after trapping acrolein molecule can be regarded as a positive factor for analyzing the electrical response of the sensor material. The adsorption energies on the doped MoS₂ nanosheets are higher than those on the pure nanosheets, indicating the principal influence of doping on the adsorption efficiency of substrate. Among the Al, Si and P doped MoS₂ systems, the highest value of adsorption energy (-0.92 eV) was observed for the Si-doped nanosheet. Also, the TiAl₃ decorated MoS₂ nanosheet exhibits a very strong adsorption effect on the acrolein molecule with considerable energy of -3.76 eV. The charge density differences for the interaction of acrolein with doped MoS₂ substrates were analyzed to search for the changes occurred at the adsorption region. Based on the obtained results, we can propose the TiAl₃ decorated MoS₂ substrates as potential sensors of acrolein molecules.

This study investigated the utilization of a unique oil shale as a sorbent for the removal of 2,4-dichlorophenol (2,4-DCP) from aqueous solutions. The influence of various process parameters, including the contact time, sorbent/liquid ratio, pH, and temperature, on the sorption process was evaluated. The results indicated the near-complete sorption of 2,4-DCP within 24 h. Favorable sorption was observed either at a sorbent/liquid ratio of 1:10, at elevated temperatures (40 °C), or at lower pH values (pH = 5) within the examined range. The maximum adsorption capacity at 40 °C has the potential to reach up to 20.0 µmol/g. Langmuir, Freundlich, and Sips isotherms were applied to the experimental data, but the Sips isotherm provided a superior fit, suggesting a heterogeneous sorption. Kinetic studies revealed a two-stage process: intraparticle diffusion dominated the initial stage, whereas other rate-limiting mechanisms may have contributed to the second stage. The first- and second-order kinetic models suggested a combined mechanism. According to the thermodynaic study, the adsorption process was spontaneous and exothermic, as indicated by the negative Gibbs free energy change and enthalpy change, which suggest that physisorption predominated. These findings demonstrate the potential of the investigated oil shale as an unconventional and cost-effective sorbent, potentially serving as a substitute for activated carbon in 2,4-DCP removal.

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The density functional theory calculations were conducted to explore the impacts of the incorporation of the Au metals on the adsorption capabilities of MoTe₂ toward thiol based S containing molecules. The most favorable positioning of Au atom is on the hollow site of MoTe₂ above three Te atoms, which gives rise to the coordination between Au and Se atoms. Most of the adsorption events focus on the substantial interaction between the S atom of considered organic molecules and the surface Au atom, which are fully described and interpreted based on the charge density and density of states plots. Thus, the favorite adsorption model for all the organic molecules is the adsorption based on strong Au-S mutual interactions. The primary aim in this work is to develop a theoretical basis to expose the potential talents of Au-MoTe₂ based nanosheets for use in smart sensors of thiol based organic molecules.

Developing efficient and effective adsorbents for lead (Pb(II)) ions is essential for promoting a sustainable, green environment and clean water. This study investigated a green composite material from tea waste and activated carbon (TW/AC) for Pb(II) ion adsorption. Structural properties, including crystal and amorphous phases, were analyzed using X-ray diffraction (XRD). The chemical bonding of the composite was identified from Fourier-transform infrared (FTIR) spectroscopy spectra, while the adsorption performance for Pb(II) ions was evaluated using atomic absorption spectroscopy (AAS). Optical properties, dielectric function, and phonon vibration before and after the adsorption process were quantitatively assessed from FTIR spectra. The highest adsorption capacity for Pb(II) ions was 167.7 mg/g at pH 7, achieved within 60 min using 80% TW. The adsorption process, supported by the amorphous structure, showed minimal changes in crystallinity, from 89.06 to 86.56%, with slight adjustments in chemical bonding and the distance between two optical phonon modes, Δ(LO-TO), reducing from 89 to 76. These findings suggest that Pb(II) ions are well-integrated into the dangling bonds of the amorphous structure, with pores acting as ion traps. The surface states identified in the TW/AC composite from FTIR spectra—such as -OH, -C = C, C = O, and -CH groups can form covalent bonds with Pb(II) ions, thereby enhancing the adsorption capacity.

This paper aims to improve the aqueous stability and electrochemical activity of HKUST-1 (or Cu₃(BTC)₂, BTC = benzene 1,3,5-tricarboxylate; and HKUST from Hong Kong University of Science and Technology) by the incorporation of Graphene Oxide (GO). The synthesis was carried out in two steps; first, Cu^II ions were pre-adsorbed on the surface of GO, and then the BTC organic linker was added to form the HKUST-1 structure dispersed on GO sheets. Two concentrations of copper were used in the synthesis, 3.57 and 14.27 mmol, to obtain the samples: GO@HKUST-1_low and GO@HKUST-1_high, respectively. N₂ adsorption properties of GO@HKUST-1_high suggest an increase in surface area compared to HKUST-1 up to 1082.0 m²·g⁻¹. In addition, the CO₂ capture of GO@HKUST-1_high increased from 5.34 (HKUST-1) to 6.92 mmol·g⁻¹ at 273 K and 100 kPa. This improvement is associated with the dispersion of the HKUST-1 on the GO sheets achieved through the synthesis strategy used, which also increased the surface area, H₂O adsorption capacity of the composite material, and electrochemical stability. After the H₂O adsorption tests, XRD confirmed that the material was stable under aqueous conditions, showing that the material did not undergo any structural modification.

In this study, an FG-g-poly(AA) hydrogel was synthesized by polymerizing acrylic acid onto fenugreek gum (FG) using MBA as a crosslinker and APS as an initiator in a hot air oven. The RSM-CCD model was employed to optimize various parameters, including the amounts of monomer, crosslinker, and initiator. The prepared hydrogel was characterized using FTIR, XRD, FE-SEM, TGA, and BET to confirm its crosslinked network, morphology, thermal stability, and surface charge. The hydrogel’s surface area, pore volume, and pore diameter were determined to be 16.332 m²/g, 0.046 cc/g, and 3.712 nm, respectively. Adsorption studies were conducted under various conditions, with different initial dye concentrations, temperatures, and pH levels. Under optimal conditions, the hydrogel achieved a maximum dye removal capacity of 97.3% for crystal violet (CV) dye within 6 h. The Langmuir isotherm model fitted the data well, and the maximal capacity for CV adsorption was 925.9 mg/g. A negative ΔG value indicates the feasibility and spontaneity of the adsorption process, while a positive ΔH suggests that the adsorption was endothermic. Thus, the synthesized hydrogel is an excellent candidate for eliminating CV dye from wastewater solutions.

Our research has generated considerable interest in MBenes because of their promising applications in chemistry, physics, and materials science. We specifically investigated the MoB₄ and MoB₂ MBene family materials for gas sensing applications through density functional theory (DFT). These calculations indicate that the MoB₄ structure exhibits a higher adsorption affinity for gases CO, CO₂, NO, NO₂, NH₃, SO, SO₂, and SO₃, while MoB₂ shows limited gas adsorption capacity. The metallic nature of the MoB₄ monolayer, its stable characteristics, and its negative adsorption energy lead to the emergence of novel states in the density of states (DOS). The metallic behavior of the MoB₄ material remains unchanged after the adsorption of gases. The CO₂, CO, NO, NO₂, and SO₃ exhibit chemisorption while NH₃, SO, and SO₂ display physisorption behavior. The gases transferred the charge to the substrate. We analyzed parameters like structural, electronic, adsorption properties, and electron localization function (ELF) concerning adsorbed gases on MoB₄. Significant charge transfers determine the material’s sensitivity to detect and adsorb various gases. ELF diagrams illustrate that all gases showed chemisorption behavior, with computed adsorption energies ranging from − 1.63 to -5.70 eV, and interaction distances observed on the MoB₄ monolayer. MoB₄ excels in detecting NO₂ gas molecules due to its exceptional sensitivity, appropriate recovery time, and remarkable stability. These insights into MoB₄ are expected to drive the discovery of new, highly conductive materials for future gas-sensing applications.