Predicted a honeycomb metallic BiC and a direct semiconducting Bi2C monolayer as excellent CO2 adsorbents

Polydopamine coating for enhanced electrostatic adsorption of methylene blue by multiwalled carbon nanotubes in alkaline environments

The removal of dye molecules in alkaline environments is an issue that should receive increased attention. In this study, the interaction mechanism between polydopamine-modified multiwalled carbon nanotubes (P-MWCNTs) and multiwalled carbon nanotubes (MWCNTs) with the cationic dye methylene blue (MB) in alkaline environments was explained in depth by adsorption, spectroscopy, and density functional theory (DFT). The mechanism of action and dominant forces between the adsorbent and adsorbate were analyzed graphically by introducing energy decomposition analysis (EDA) and an independent gradient model (IGM) into the DFT calculations. In addition, the force distribution was investigated through an isosurface. Moreover, batch adsorption studies were conducted to evaluate the performance of MWCNTs and P-MWCNTs for MB removal in alkaline environments. The maximum MB adsorption capacities of the MWCNTs and P-MWCNTs in solution were 113.3 mg‧g-1 and 230.4 mg‧g-1, respectively, at pH 9. The IGM and EDA showed that the better adsorption capacity of the P-MWCNTs originated from the enhancement of the electrostatic effect by the proton dissociation of polydopamine. Moreover, the adsorption of MB by MWCNTs and P-MWCNTs in alkaline environments was governed by dispersion and electrostatic effects, respectively. Through this study, it is hoped that progress will be made in the use of DFT to explore the mechanism of adsorbent-adsorbate interactions.

Efficient adsorption of methylene blue in water by nitro-functionalized metal-organic skeleton‑calcium alginate composite aerogel

This paper presents the first investigation of the adsorption performance of methylene blue by the nitro-functionalized metal-organic framework (MIL-88B-NO2). MIL-88B-NO2 has a specific surface area of 836.0 m2/g, which is 109.8 % higher than MIL-88B. The maximum adsorption capacity of methylene blue is 383.6 mg/g, which is 68.2 % higher than that of MIL-88B. This phenomenon can be attributed to the great increase in specific surface area and the introduction of nitro-functional groups. However, its microcrystalline nature makes it difficult to remove in practical applications and quickly causes secondary pollution. Therefore, the composite of MIL-88B-NO2 and calcium alginate (CA) to form aerogel maintains the inherent properties of the two materials and makes it easy to recycle. The utmost adsorption capability of MIL-88B-NO2/CA-2 aerogel is 721.0 mg/g. Compared with MIL-88B-NO2, the adsorption performance of MIL-88B-NO2/CA-2 aerogel is further improved by 88.0 %. The higher adsorption capacity of the adsorbent may be due to the synergistic interplay of electrostatic attraction, π-π conjugation, hydrogen bonding, metal coordination effect, and physicochemical properties. Also, MIL-88B-NO2/CA-2 aerogel has good recyclability, indicating that it has broad application prospects in the removal of positive dyes in contaminated water.

Hydrothermal Pretreatment of KOH for the Preparation of PAC and Its Adsorption on TC

The environment has been heavily contaminated with tetracycline (TC) due to its excessive use; however, activated carbon possessing well-developed pores can effectively adsorb TC. This study synthesized pinecone-derived activated carbon (PAC) with high specific surface area (1744.659 cm²/g, 1688.427 cm²/g) and high adsorption properties (840.62 mg/g, 827.33 mg/g) via hydrothermal pretreatment methods utilizing pinecones as precursors. The results showed that PAC treated with 6% KOH solution had excellent adsorption properties. It is found that the adsorption process accords with the PSO model, and a large amount of C=C in PAC provides the carrier for π-πEDA interaction. The results of characterization and the isothermal model show that TC plays a key role in the adsorption process of PAC. It is concluded that the adsorption process of TC on PAC prepared by hydrothermal pretreatment is mainly pore filling and π-πEDA interaction, which makes it a promising adsorbent for TC adsorption.

Modeling the CO2 separation capability of poly(4-methyl-1-pentane) membrane modified with different nanoparticles by artificial neural networks

Membranes are a potential technology to reduce energy consumption as well as environmental challenges considering the separation processes. A new class of this technology, namely mixed matrix membrane (MMM) can be fabricated by dispersing solid substances in a polymeric medium. In this way, the poly(4-methyl-1-pentene)-based MMMs have attracted great attention to capturing carbon dioxide (CO2), which is an environmental pollutant with a greenhouse effect. The CO2 permeability in different MMMs constituted of poly(4-methyl-1-pentene) (PMP) and nanoparticles was comprehensively analyzed from the experimental point of view. In addition, a straightforward mathematical model is necessary to compute the CO2 permeability before constructing the related PMP-based separation process. Hence, the current study employs multilayer perceptron artificial neural networks (MLP-ANN) to relate the CO2 permeability in PMP/nanoparticle MMMs to the membrane composition (additive type and dose) and pressure. Accordingly, the effect of these independent variables on CO2 permeability in PMP-based membranes is explored using multiple linear regression analysis. It was figured out that the CO2 permeability has a direct relationship with all independent variables, while the nanoparticle dose is the strongest one. The MLP-ANN structural features have efficiently demonstrated an appealing potential to achieve the highest accurate prediction for CO2 permeability. A two-layer MLP-ANN with the 3-8-1 topology trained by the Bayesian regulation algorithm is identified as the best model for the considered problem. This model simulates 112 experimentally measured CO2 permeability in PMP/ZnO, PMP/Al2O3, PMP/TiO2, and PMP/TiO2-NT with an excellent absolute average relative deviation (AARD) of lower than 5.5%, mean absolute error (MAE) of 6.87 and correlation coefficient (R) of higher than 0.99470. It was found that the mixed matrix membrane constituted of PMP and TiO2-NT (functionalized nanotube with titanium dioxide) is the best medium for CO2 separation.

Insight into the adsorptive removal of ibuprofen using porous carbonaceous materials: A review

Over the last decade, the removal of pharmaceuticals from aquatic bodies has garnered substantial attention from the scientific community. Ibuprofen (IBP), a non-steroidal anti-inflammatory drug, is released into the environment in pharmaceutical waste as well as medical, hospital, and household effluents. Adsorption technology is a highly efficient approach to reduce the IBP in the aquatic environment, particularly at low IBP concentrations. Due to the exceptional surface properties of carbonaceous materials, they are considered ideal adsorbents for the IBP removal of, with high binding capacity. Given the importance of the topic, the adsorptive removal of IBP from effluent using various carbonaceous adsorbents, including activated carbon, biochar, graphene-based materials, and carbon nanostructures, has been compiled and critically reviewed. Furthermore, the adsorption behavior, binding mechanisms, the most effective parameters, thermodynamics, and regeneration methods as well as the cost analysis were comprehensively reviewed for modified and unmodified carbonaceous adsorbents. The compiled studies on the IBP adsorption shows that the IBP uptake of some carbon-based adsorbents is significantly than that of commercial activated carbons. In the future, much attention is needed for practical utilization and upscaling of the research findings to aid the management and sustainability of water resource.

DFT study of adsorbing SO2, NO2, and NH3 gases based on pristine and carbon-doped Al24N24 nanocages

The adsorption of SO₂, NO₂, and NH₃ toxic gases on Al₂₄N₂₄ and Al₂₄N₂₃C nanocages was investigated by using density functional theory (DFT) calculations. The adsorption energies, frontier orbitals, charge transfer using natural bonding orbital (NBO) analysis, dipole moment, the partial density of states (PDOS), thermodynamic relationships, non-covalent interaction (NCI), and quantum theory of atoms in molecules (QTAIM) were considered. The results reveal that carbon-doped Al₂₄N₂₄ nanocage increases the adsorption energies for SO₂ and NO₂ gases while decreasing the adsorption energy of NH₃ gas. The ΔG for all configurations were negative except the configurations A1 and G2 confirming the weak adsorption of these two complexes. In conclusion, Al₂₄N₂₄ and Al₂₄N₂₃C nanocages are in general promising adsorbents for the removal of SO₂, NO₂, and NH₃ toxic gases. The Al₂₄N₂₄ and Al₂₄N₂₃C nanocages are ideal electronic materials.

The elimination and extraction of organosulfur compounds from real water and soil samples using metal organic framework/graphene oxide as a novel and efficient nanocomposite

In the present work, an efficient metal organic framework/graphene oxide (MOF-801/GO) sorbent was fabricated and employed for the detection of organosulfur pesticides (OSPs) in real samples using gas chromatography-flame photometric detection (GC-FPD). The optimal extraction parameters for the suggested solid-phase extraction (SPE) include sorbent amount (60 mg), extraction solvent (acetonitrile) and extraction time (5 min). The linear dynamic ranges and detection limits for organosulfur pesticides (OSPs) samples under above extraction conditions were ranged from 0.5 to 300 μg L^-1 and 0.1-1.1 μg L^-1, respectively. Moreover, the proposed SPE/GC-FDP method was applied for the analysis of pesticides in different real environmental water and soil samples. The obtained recoveries of the analytes in were between 92.0 and 106.8% and relative standard deviation (RSD) values were lower than 9.2%. The application of the MOF-801/GO as a sorbent in dSPE of OSPs analytes showed to be reliable, fast and sensible methodology for pesticides monitoring in different environmental samples.

Spin-Resolved Band Structure of Hoffman Clathrate [Fe(pz)2Pt(CN)4] as an Essential Tool to Predict Optical Spectra of Metal-Organic Frameworks

Paramount spin-crossover properties of the 3D-Hoffman metalorganic framework (MOF) [Fe(pz)₂Pt(CN)₄] are generally described on the basis of the ligand field theory, which provides adequate insight into theoretical and simulation analysis of spintronic complexes. However, the ligand field approximation does not take into account the 3D periodicity of the actual complex lattice and surface effects and therefore cannot predict a full-scale periodic structure without utilizing more advanced methods. Therefore, in this paper, the electronic properties of the exemplar MOF were analyzed from the band structure perspective in low-spin (LS) and high-spin (HS) states. The density-of-states spectra determined for both spin-up and spin-down electrons of Fe d⁶ orbitals indicate spin-orbital splitting and delocalization for HS due to spin polarization in the iron atom ligand field. Presence of the surface states in the real crystal causes a red shift of the metal-metal charge transfer (MMCT) and metal-ligand charge transfer (MLCT) peaks for both HS and LS states. The addition of residual water molecules and disorder among the pyrazine rings reveal additional influences on the positions of the pyrazine band and, therefore, on the absorption spectra of the crystal. The results show a magnification of the peak correlated with the MLCT in the HS state and a significant red shift of the LS characteristic absorption band. The presented approach involving band structure analysis delivers a more complete image of the electronic properties of the [Fe(pz)₂Pt(CN)₄] crystalline network and can be a landmark for insightful studies of other MOFs.

Effects of Ge, Si, and B doping on the adsorption and detection properties of C60 fullerene towards methadone in gas and aqua phases: a DFT study

CONTEXT

Methadone can be abused and caused addictive and has various side effects. Therefore, the development of a fast and reliable diagnosis technique for its monitoring is essential. In this work, applications of C₆₀, GeC₅₉, SiC₅₉, and BC₅₉ fullerenes were investigated utilizing density functional theory (DFT) to find a suitable probe for methadone detection. The C₆₀ fullerene indicated weak adsorption energy for methadone sensing. Therefore, for the construction of the fullerene with good property for methadone adsorption and sensing, the GeC₅₉, SiC₅₉, and BC₅₉ fullerenes have been studied. The adsorption energy of GeC₅₉, SiC₅₉, and BC₅₉ in the most stable complexes were calculated at -2.08, -1.26, and -0.71 eV, respectively. Although GeC₅₉, SiC₅₉, and BC₅₉ all showed strong adsorption, only BC₅₉ present a high sensitivity for detection. Further, the BC₅₉ fullerene showing a proper short recovery time (about 1.11 × 10^-6 s for methadone desorption). Water as a solution is used to simulate the behavior of fullerenes in the body fluids, and results indicated that the selected pure and complex nanostructures are stable in water. The UV-vis spectrums indicated that the after adsorption of methadone on the BC₅₉ exhibits shift toward the lower wavelengths (blue shift). Therefore, our investigation indicated that the BC₅₉ fullerene is an excellent candidate for methadone detection.

METHODS

The interaction of methadone with pristine and doped C60 fullerenes surfaces was calculated using the density functional theory calculations. The GAMESS program and M06-2X method with a 6-31G(d) basis set were used for computations. Since the M06-2X method overestimates the LUMO-HOMO energy gaps (Eg) of carbon nanostructures, the HOMO and LUMO energies and Eg were investigated at the B3LYP/6-31G(d) level of theory using the optimization calculations. UV-vis spectra of excited species were obtained through the time-dependent density functional theory. To simulate the human biological fluid, the solvent phase was also evaluated in adsorption studies, and water was considered a liquid solvent.

A graphene-like semiconducting BC2P monolayer as a promising material for a Li-ion battery and CO2 adsorbent

Searching for high-performance anode materials and CO₂ adsorption materials are key factors for next-generation renewable energy technologies and mitigation of the greenhouse effect. Herein, we report a novel two-dimensional (2D) BC₂P monolayer with great potential as an anode material for lithium-ion batteries (LIBs) and as a material for CO₂ adsorption. The adsorption energies of Li atoms and CO₂ molecules on the BC₂P supercell are negative enough to assure stability and safety under operating conditions. More intriguingly, the BC₂P monolayer possesses a very high theoretical capacity of 1018.8 mA g h^-1 for LIBs. In addition, the diffusion energy barriers of Li on the BC₂P supercell are 0.26 and 0.87 eV, showing good charge/discharge capability, and the electrode potential of Li is beneficial to their performance as an anode material. Moreover, four chemical and three physical adsorption sites were verified, indicating that the CO₂ molecule was effectively adsorbed on the BC₂P supercell. These desirable properties make the BC₂P monolayer a promising 2D material for application in LIBs and for CO₂ adsorbents aimed at highly efficient CO₂ capture.

Modification of the Textural Properties of Chitosan to Obtain Biochars for CO2-Capture Processes

Three chitosans with different morphologies have been used (commercial chitosan powder, chitosan in film form and chitosan in globular form synthesized by the freeze-dried method) for the synthesis of biochars. The pyrolytic treatment has revealed that the biochar synthesized from the chitosan formed by the freeze-dried method reaches the highest CO₂-adsorption capacity (4.11 mmol/g at 0 °C and a pressure of 1 bar) due to this adsorbent is highly microporous. Moreover, this biochar is more resistant to the pyrolytic treatment in comparison to the biochars obtained from the commercial chitosan and chitosan in the form of film. CO₂-adsorption studies at different temperatures have also shown that the adsorption capacity diminishes as the adsorption temperature increases, thus suggesting that the adsorption takes place by a physical process.

Insights into the Synergistic Removal of Copper(II), Cadmium(II), and Chromium(III) Ions Using Modified Chitosan Based on Schiff Bases-g-poly(acrylonitrile)

Chitosan has received broad consideration as an adsorbent for all pollutants because of its low cost and great adsorption potential. However, its shortcomings, including sensitivity to pH, poor thermal stability, and poor mechanical strength, limit its use. The functional groups of chitosan can be modified to enhance its performance by the grafting technique and Schiff base modification. The grafting process used acrylonitrile (Ch-g-PAN) as a monomer and potassium persulfate as an initiator. After that, the modification via preparation of the Schiff base reaction using salicylaldehyde (Ch-g-Sch I) and P-anisaldehyde (Ch-g-Sch II) was carried out. The synthesized copolymers were detailed and characterized through several spectroscopic and microscopic techniques including infrared spectroscopy, scanning electron microscopy, and X-ray diffraction. In addition, Ch-g-Sch I and Ch-g-Sch II were applied in the removal of different metal ions such as Cu²⁺, Cd²⁺, and Cr³⁺. The maximum adsorption capacity of Ch-g-Sch I for Cd²⁺ was 183.7 mg g^-1 in 24 h, while in the case of Ch-g-Sch II, the maximum adsorption capacity for Cd²⁺ was improved to 322.9 mg g^-1 for the same time. Moreover, adsorption thermodynamic analysis displays that the all ion adsorption process was not random and the pseudo-second-order model fitted with experimental results. Finally, Ch-g-Sch I and Ch-g-Sch II were applied as designs for industrial wastewater treatment with significant efficiency.

A novel approach based on the ultrasonic-assisted microwave method for the efficient synthesis of Sc-MOF@SiO2 core/shell nanostructures for H2S gas adsorption: A controllable systematic study for a green future

In this work, for the first time, novel Sc-MOF@SiO₂ core/shell nanostructures have been synthesized under the optimal conditions of ultrasonic-assisted microwave routes. The final products showed small particle size distributions with homogeneous morphology (SEM results), high thermal stability (TG curve), high surface area (BET adsorption/desorption techniques), and significant porosity (BJH method). The final nanostructures of Sc-MOF@SiO₂ core/shell with such distinct properties were used as a new compound for H₂S adsorption. It was used with the systematic investigation based on a 2^K−1 factorial design, which showed high-performance adsorption of about 5 mmol/g for these novel adsorbents; the optimal experimental conditions included pressure, 1.5 bar; contact time, 20 min; and temperature, 20°C. This study and its results promise a green future for the potential control of gas pollutants.

Activated Carbon Modified by Ester Hydrolysis of Ethyl Acetate for Water Vapor Adsorption Enhancement

To improve water vapor adsorption, this study employed oxalic acid–ethyl acetate acidic hydrolysis to modify honeycomb activated carbon and introduce hydrophilic functional groups. Scanning electron microscopy (SEM), Boehm titration, Fourier transform infrared spectroscopy (FT-IR), and an automatic surface area analyzer (BET) were used to characterize the microscopic morphology, surface functional groups, specific surface area, and pore size changes. The results showed that, when the concentration of oxalic acid is 0.0006 mol/cm3, the specific surface area is 179.06 m2/g. After hydrolysis with ethyl acetate, the original functional groups became more abundant, while the number of total acidic functional groups on the surface grew from 0.497 mmol/g to 1.437 mmol/g. The static water vapor adsorption experiments were conducted on modified activated carbon under constant temperature and humidity conditions. Compared with unmodified activated carbon, the activated carbon modified with 0.0006 mol/cm3 oxalic acid increased the adsorption capacity of water vapor by 15.7%. The adsorption capacity of activated carbon after being combined with 0.0006 mol/cm3 oxalic acid and ester hydrolysis modification increased by 37.1%. At the same temperature, the adsorption capacity increased with a higher relative humidity. At the same relative humidity, the adsorption capacity decreased as the temperature rose. Therefore, this modification method may provide clues for the application of enhancing the hygroscopic ability of activated carbon.

Simultaneous Removal of SO2 and NO by O3 Oxidation Combined with Seawater as Absorbent

Aiming at NOx (NO 90%, NO2 10%) and SO2 in simulated vessel emissions, denitration and desulfurization were studied through ozone oxidation combined with seawater as absorbent. Specifically, the different influencing factors of denitration and desulfurization were analyzed. The results indicated that the oxidation efficiency of NO can reach over 90% when the molar ratio of O3/NO is 1.2. Ozone oxidation and seawater washing in the same unit can decrease the temperature of ozone oxidation of NO, avoid high temperature ozone decomposition, and enhance the oxidation efficiency of NO. When NO inlet initial concentration is lower than 800 ppm, the NOx removal efficiency can be improved by increasing NO inlet concentration, and when NO inlet initial concentration is greater than 800 ppm, increasing the concentration of NO would decrease the NOx removal efficiency. Increasing the inlet concentration of SO2 has minor effect on desulfurization, but slightly reduces the absorption efficiency of NOx due to the competition of SO2 and NOx in the absorption solution. Besides, final products (NO2−, NO3−, SO32−, and SO42−) were analyzed by the ion chromatography.

Ultrasonic-assisted synthesis of zeolite/activated carbon@MnO2 composite as a novel adsorbent for treatment of wastewater containing methylene blue and brilliant blue

In this study, zeolite/activated carbon@MnO₂ composite was used as a novel adsorbent to eliminate methylene blue (MB) and brilliant blue (BB) dyes from aqueous media. To this end, activated carbon (AC) was produced by Ziziphus Spina-Christi leaves and then used to synthesize zeolite/AC@MnO₂ composite. Various analyses such as BET, SEM, EDX, Map, FTIR, and XRD were performed to determine the surface features of the above composite. BET analysis indicated that the aforementioned composite has a mesoporous structure. Also, the best conditions for the adsorption of MB and BB dyes were obtained at pH of 9 and 2, temperature of 25 °C, adsorbent dosage of 1 and 2 g/L, initial dye concentration of 10 mg/L, and contact time of 40 and 60 min, respectively. Under optimal conditions, the utmost removal efficiency of MB and BB dyes using the zeolite/AC@MnO₂ composite was 98.43% and 96.54%, respectively, indicating significant adsorption efficiencies. Moreover, the utmost adsorption capacity of MB and BB dyes was 67.56 and 66.22 mg/g, respectively. Furthermore, intraparticle and film diffusion mechanisms were very important in the adsorption process. Besides, thermodynamic and equilibrium studies indicated that the adsorption process is exothermic, physical, and spontaneous. Generally, the aforementioned composite has a significant adsorption capacity and can be a suitable adsorbent to eliminate cationic dyes from industrial effluents.

A Review of High-Energy Density Lithium-Air Battery Technology: Investigating the Effect of Oxides and Nanocatalysts

In vehicles that require a lot of electricity, such as electric vehicles, it is necessary to use high-energy batteries. Among the developed batteries, the lithium-ion battery has shown better performance. This battery has an energy density of 10 equal to that of a lithium-ion battery and uses air oxygen as the active material of the cathode and anode like a lithium-ion battery made of lithium metal. The cathode used in these batteries must have special properties such as strong catalytic activity and high conductivity, and nanotechnology has greatly helped to improve the materials used in the cathode of lithium-air batteries. The importance of proper catalyst distribution and the relationship between the oxide product and the catalyst and the indirect effect of the ORR catalyst on the OER reaction is not present in the fuel cell. The maximum capacity of lithium-air battery theory using graphene under optimal electron conduction conditions and the experimental maximum obtained for graphene by optimizing the structure geometry, examples of structural engineering using carbon fiber and carbon nanotubes in cathode fabrication with the ability to perform the reaction properly while providing space for lithium oxide placement, are examined. This article describes the mechanism of this battery, and its components are examined. The challenges of using this battery and the application of nanotechnology to solve these challenges are also discussed.

Density functional theory investigation of ozone gas uptake by a BeO nanoflake

Due to importance of the gas uptake topic in environment and energy issues, this work was performed for investigating ozone (Oz) gas uptake by means of a beryllium oxide (BeO) nanoflake. To this aim, density functional theory (DFT) calculations and the quantum theory of atoms in molecules (QTAIM) analysis were performed. The monolayer BeO nanoflake was decorated by a HEME-like N4Fe region to prepare an interacting region towards the Oz uptake. Accordingly, three models were optimized based on configurations of Oz molecule relaxation at the BeO surface, in which two types of O ... Fe and O ... N interactions were observed. In this case, Oz3@BeO model was involved with two mentioned types of interactions and three occurred interaction between Oz and BeO making it as the strongest bimolecular formation model of Oz@BeO. Moreover, electronic molecular orbital features indicated that the models formations could be also related to sensor functions by variations of electric conductivity because of Oz gas uptake. As a consequence, the investigated BeO nanoflake of this work was proposed for employing in Oz gas uptake for different purposes.

Double chelation of Iron through dimer formation of favipiravir: Density functional theory analysis

This work was performed to examine an idea about full chelation of Iron (Fe) by well-known favipiravir (Fav) as a possible mechanism of action for medication of COVID-19 patients. To this aim, formations of Fe- mediated dimers of Fav were investigated by performing density functional theory (DFT) computations of electronic and structural features for singular and dimer models. The results indicated that the models of dimers were suitable for formation, in which two cis (D1) and trans (D2) models were obtained regarding the configurations of two Fav counterparts towards each other. Energy results indicated that formation of D1 was slightly more favorable than formation of D2. Molecular orbital features affirmed hypothesized interacting sites of Fav for Fe-mediated dimers formations, in which atomic charges and other molecular orbital related representations affirmed such achievements. Moreover, detection of such dimer formation was also possible by monitoring variations of molecular orbitals features. As a consequence, formations of Fe-mediated dimers of Fav could be achievable for possible removal of excess of Fe as a proposed mechanism of action for Fav in medication of COVID-19 patients.

Evaluation of the multifunctional activity of silver bionanocomposites in environmental remediation and inhibition of the growth of multidrug-resistant pathogens

Imperata cylindrica cellulose supported Ag bionanocomposites purified industrial water and controlled the contagious diseases with high potential activity.