Metal–organic structures have great potential for practical applications in many areas. However, their widespread use is often hindered by time-consuming and expensive synthesis procedures that often ...involve hazardous solvents and, therefore, generate wastes that need to be remediated and/or recycled. The development of cleaner, safer, and more sustainable synthesis methods is extremely important and is needed in the context of green chemistry. In this work, a facile mechanochemical method involving water-assisted ball milling was used for the synthesis of MOF-303. The obtained MOF-303 exhibited a high specific surface area of 1180 msup.2/g and showed an excellent COsub.2 adsorption capacity of 9.5 mmol/g at 0 °C and under 1 bar.
Adsorption of Cs on Al.sub.0.5Ga.sub.0.5N Ji, Yanjun; Wang, Junping; Du, Yujie
The European physical journal. B, Condensed matter physics,
05/2023, Volume:
96, Issue:
5
Journal Article
Peer reviewed
The first-principles was employed to calculate the adsorption of Cs on (2 x 2) Al(Mg).sub.0.5Ga.sub.0.5N and Al.sub.0.5 Ga(Mg).sub.0.5N surfaces using density-functional theory within a plane-wave ...ultrasoft pseudopotential scheme. Then, the surface morphology, stability, work functions and Cs adsorptions of Al(Mg).sub.0.5Ga.sub.0.5N and Al.sub.0.5 Ga(Mg).sub.0.5N surfaces were investigated. The results reveal that Al(Mg).sub.0.5Ga.sub.0.5N surface with Mg in the first layer was more suitable for ultraviolet cathode. The most stable adsorption site for adsorption of Cs on the Al(Mg).sub.0.5Ga.sub.0.5N surface was found on N top. With the increase of Cs coverage, the interaction between Cs and atoms in the first layer of surface and that between Cs and Cs was enhanced, the surface dipole moment increased, the work function decreased, the carrier concentration and the absorption in visible light increased. When Cs coverage was greater than 0.5ML, the adsorption of Cs reached saturation, the deformation of surface structure appeared, the adsorption in visible light was greater than that in UV, and the surface was no longer suitable for UV detection. The results show that 0.5ML is the turning point of Cs coverage for the surface doped with Mg.
The first-principles was employed to calculate the adsorption of Cs on (2 x 2) Al(Mg).sub.0.5Ga.sub.0.5N and Al.sub.0.5 Ga(Mg).sub.0.5N surfaces using density-functional theory within a plane-wave ...ultrasoft pseudopotential scheme. Then, the surface morphology, stability, work functions and Cs adsorptions of Al(Mg).sub.0.5Ga.sub.0.5N and Al.sub.0.5 Ga(Mg).sub.0.5N surfaces were investigated. The results reveal that Al(Mg).sub.0.5Ga.sub.0.5N surface with Mg in the first layer was more suitable for ultraviolet cathode. The most stable adsorption site for adsorption of Cs on the Al(Mg).sub.0.5Ga.sub.0.5N surface was found on N top. With the increase of Cs coverage, the interaction between Cs and atoms in the first layer of surface and that between Cs and Cs was enhanced, the surface dipole moment increased, the work function decreased, the carrier concentration and the absorption in visible light increased. When Cs coverage was greater than 0.5ML, the adsorption of Cs reached saturation, the deformation of surface structure appeared, the adsorption in visible light was greater than that in UV, and the surface was no longer suitable for UV detection. The results show that 0.5ML is the turning point of Cs coverage for the surface doped with Mg. Graphical abstract
γ-Fesub.2Osub.3 is considered to be a promising catalyst for the selective catalytic reduction (SCR) of nitrogen oxide (NOsub.x). In this study, first-principle calculations based on the density ...function theory (DFT) were utilized to explore the adsorption mechanism of NHsub.3, NO, and other molecules on γ-Fesub.2Osub.3, which is identified as a crucial step in the SCR process to eliminate NOsub.x from coal-fired flue gas. The adsorption characteristics of reactants (NHsub.3 and NOsub.x) and products (Nsub.2 and Hsub.2O) at different active sites of the γ-Fesub.2Osub.3 (111) surface were investigated. The results show that the NHsub.3 was preferably adsorbed on the octahedral Fe site, with the N atom bonding to the octahedral Fe site. Both octahedral and tetrahedral Fe atoms were likely involved in bonding with the N and O atoms during the NO adsorption. The NO tended to be adsorbed on the tetrahedral Fe site though the combination of the N atom and the Fe site. Meanwhile, the simultaneous bonding of N and O atoms with surface sites made the adsorption more stable than that of single atom bonding. The γ-Fesub.2Osub.3 (111) surface exhibited a low adsorption energy for Nsub.2 and Hsub.2O, suggesting that they could be adsorbed onto the surface but were readily desorbed, thus facilitating the SCR reaction. This work is conducive to reveal the reaction mechanism of SCR on γ-Fesub.2Osub.3 and contributes to the development of low-temperature iron-based SCR catalysts.
A C/CdS/TiO.sub.2 composite was prepared by a calcination method using sodium alginate (SA) as a medium. Remarkably, two nano-photocatalysts, TiO.sub.2 and CdS, were formed onto the carbon-based ...materials during calcination. The as-prepared hybrid materials were characterized and analyzed by XRD, SEM, TEM, XPS, UV-vis DRS, and PL techniques. The results showed that the coating of SA on the CH.sub.4N.sub.2S surface decreased the volatilization of CH.sub.4N.sub.2S. The carbon-based materials can not only play the role of a bridge connecting CdS and TiO.sub.2 for the efficient absorption of UV light, but also promote the construction of Z-scheme heterojunctions. The prepared photocatalysts were used in simultaneous adsorption and photocatalysis processes for the removal of organic dyes (cationic yellow X-GL) from aqueous solutions. After 60 min of UV irradiation, the photocatalytic decolorization rate of cationic yellow X-GL in aqueous solutions by C/CdS/TiO.sub.2 composite could reach 97.02%, which was 27% higher than that of TiO.sub.2. The reason was mainly due to the synergistic effect including the interface enhancement effect of hierarchical structure and the separation efficiency of photogenerated carriers. Additionally, it showed good recyclability making a promising photocatalyst material for the degradation of textile dyes.
It is highly desired to enhance charge separation and Osub.2 adsorption of the pyropheophorbide-a (Ppa) to promote visible-light activity and stability. Herein, Ppa modified 001-facet-exposed ...TiOsub.2 nanosheets (Ppa/001T) nanocomposites with different weight ratios were fabricated via the self-assembly approach by OH induced. Compared with the bare Ppa, the 8% amount optimized 8Ppa/001T sample displayed 41-fold enhanced activity for degradation of Ametryn (AME) under visible-light irradiation. The promoted photoactivities could be attributed to the accelerated charge carrier's separation by coupling TiOsub.2 as thermodynamic platform for accepting the photoelectrons with high energy from Ppa and the promoted Osub.2 adsorption because of the residual fluoride on TiOsub.2. As for this, a distinctive two radicals (*Osub.2 sup.− and *OH) involved pathway of AME degradation is carried out, which is different from the radical pathway dominated by *Osub.2 sup.− for the bare Ppa. This work is of utmost importance since it gives us detailed information regarding the charge carrier's separation and the impact of the radical pathway that will pave a new approach toward the design of high activity visible-light driven photocatalysts.
The adsorption properties of microporous spherical carbon materials obtained from the resorcinol-formaldehyde resin, treated in a solvothermal reactor heated with microwaves and then subjected to ...carbonization, are presented. The potassium-based activation of carbon spheres was carried out in two ways: solution-based and solid-based methods. The effect of various factors, such as chemical agent selection, chemical activating agent content, and the temperature or time of activation, was investigated. The influence of microwave treatment on the adsorption properties was also investigated and described. The adsorption performance of carbon spheres was evaluated in detail by examining COsub.2 adsorption from the gas phase.
In this study, we conducted a comprehensive investigation into activated carbons derived from avocado stones produced through chemical activation using sulfuric acid. The analysis encompassed X-ray ...diffraction (XRD) spectra, FTIR, SEM and essential textural parameters, namely specific surface area, total pore volume, and micropore volume. Moreover, we scrutinized carbon dioxide adsorption isotherms and subjected the experimental data to fit with both two-parameter and four-parameter equilibrium isotherm models. To achieve the most accurate parameter estimation, five error functions were employed. Furthermore, we calculated the isosteric heat of adsorption for the most promising COsub.2 sorbent, providing valuable insights into the thermodynamic aspects of the adsorption process.
Industrial wastewater effluents containing dyes are considered to pollute and be harmful to the environment. Among the various removal techniques, the adsorption process using low-cost adsorbents has ...been successfully used to remove pollutants. In this work, Aloe vera leaves (AVs) have been used as adsorbent for the removal of Orange II (O-II). A three-level three-factor Box–Behnken factorial design, including three replicates of center points, was applied to investigate the main parameters affecting the biosorption of O-II dye in aqueous solutions by AVs. The selected parameters were adsorbent dose, initial dye concentration, and contact time. The Box–Behnken experiment design has given a satisfactory result for the optimization of the adsorption process. The obtained value of Rsup.2 (0.9993) shows that the quadratic response model adequately represents the relationship between each response and the chosen variables. The pH influences the adsorption capacity, obtaining at pH 2 the maximum adsorption capacity value. From the kinetic models studied, the one that best describes the adsorption of Orange II on Aloe vera is the Bangham model (ARE = 1.06%). The isotherm model that best represents the experimental data is the Toth model. The maximum adsorption capacity obtained by this model was 15.9 mg·gsup.−1.
CdS/g-C.sub.3N.sub.4 (CdS/CN) type II heterojunction photocatalyst was prepared by an improved successive ionic layer adsorption and reaction process. TEM results show that the CdS nanoparticles (CdS ...NPs) were successfully loaded on the surface of CN. The results of PL and PEC display that the construction of CdS/CN heterojunction benefits the transmission of the photogenerated carriers and effectively inhibits the photogenerated carrier recombination in photocatalytic process. The photodegradation experiments exhibit that the 3-CdS/CN photocatalyst possesses the highest photodegradation performance over the other samples. The yields of H.sub.2 and CH.sub.4, in the presence of the best CdS/CN photocatalyst (1-CdS/CN) are 50 and 13 times stronger, respectively, than in the case of the pure CN in the photoreduction process of CO.sub.2. The CN coupling effectively improves the photocatalytic performance of CdS-based photocatalyst and inhibits the hole-induced photocorrosion of CdS NPs. A possible type II heterojunction photocatalytic mechanism has been provided.
