Synthesis of activated carbon/MgO monolith using Astragalus material for carbon dioxide adsorption

A mononuclear square-planar CuII complex of (5-methyl-1H-pyrazol-3-yl)carbamate, [Cu(C5H6N3O2)2]·4H2O, was synthesized using a one-pot reaction from 5-methyl-3-pyrazolamine and copper(II) acetate in water under ambient conditions. The adsorption of carbon dioxide from air was facilitated by the addition of di-ethano-lamine to the reaction mixture. While di-ethano-lamine is not a component of the final product, it plays a pivotal role in the reaction by creating an alkaline environment, thereby enabling the adsorption of atmos-pheric carbon dioxide. The central copper(II) atom is in an (N2O2) square-planar coordination environment formed by two N atoms and two O atoms of two equivalent (5-methyl-1H-pyrazol-3-yl)carbamate ligands. Additionally, there are co-crystallized water mol-ecules within the crystal structure of this compound. These co-crystallized water mol-ecules are linked to the CuII mononuclear complex by O-H⋯O hydrogen bonds. According to Hirshfeld surface analysis, the most frequently observed weak inter-molecular inter-actions are H⋯O/O⋯H (33.6%), H⋯C/C⋯H (11.3%) and H⋯N/N⋯H (9.0%) contacts.

Activated carbon (AC) has been used widely as an agent for carbon dioxide (CO2) adsorption due to its environmentally friendly nature, low cost, high porous structure, high surface area and good mechanical properties. Modifications have been made to AC in order to enhance its adsorptive properties. In this study, the performance of activated carbon modified by hydrothermal treatment and impregnation techniques was compared using metal oxides. The prepared samples were characterized by different techniques using X-ray diffraction (XRD) and scanning electron microscopy (SEM). The adsorption of CO2 was investigated using a CO2 adsorption unit, whereby 20% of CO2 gas was passed through the samples until a breakthrough point was achieved. During the adsorption study, it was found that AC that had been hydrothermally treated with cerium oxide (CeO2) had the highest adsorption capacity of 0.856 mmol/g with a breakthrough time of 19.33 min.

Influence of nitric acid concentration on the characteristics of active carbons obtained from a mineral coal

The adsorption of carbon dioxide (CO2) on activated carbon (AC) prepared from olive trees has been investigated by using a fixed bed adsorption apparatus. The adsorption equilibrium and breakthrough curves were determined at different temperatures 30, 50, 70, and 90°C in order to investigate both kinetic and thermodynamic parameters. Maximum CO2 sorption capacity on AC ranged from 109.5 to 35.46 and from 129.65 to 35.55 mg CO2/g of AC for initial concentrations 10 and 13.725% vol., respectively. Different isotherm models are applied to mathematically model the CO2 adsorption, and on the basis of the estimated adsorption capacity by model and determination coefficient (r2), the Langmuir model provides a perfect fit to the experimental data owing to closeness of the r2 to unity. From the correlation coefficient, it is found that the pseudo-second-order model is well-fitted with the experimental data. In addition, it indicates that CO2 adsorption is a physical adsorption process and demonstrates a behavior of an exothermic reaction, which is consistent with the thermodynamic analysis. The results obtained in this study conclude that AC prepared from olive trees can be considered as adequate for designing a fixed bed cycle to separate carbon dioxide from flue gases and serve as a benchmark while searching for inexpensive and superior activated carbon production in future studies.

In recent years, the scientific community has given more and more attention to the issue of climate change and global warming, which is largely attributed to the massive quantity of carbon dioxide emissions. Thus, the demand for a carbon dioxide capture material is massive and continuously increasing. In this study, we perform first-principle calculations based on density functional theory to investigate the carbon dioxide capture ability of pristine and doped beryllonitrene. Our results show that carbon dioxide had an adsorption energy of −0.046 eV on pristine beryllonitrene, so it appears that beryllonitrene has extremely weak carbon dioxide adsorption ability. Pristine beryllonitrene could be effectively doped with lithium atoms, and the resulting Li-doped beryllonitrene had much stronger interactions with carbon dioxide than pristine beryllonitrene. The adsorption energy for carbon dioxide on Li-doped beryllonitrene was −0.408 eV. The adsorption of carbon dioxide on Li-doped beryllonitrene greatly changed the charge density, projected density of states, and band structure of the material, demonstrating that it was strongly adsorbed. This suggests that Li-doping is a viable way to enhance the carbon dioxide capture ability of beryllonitrene and makes it a possible candidate for an effective CO2 capture material.

Metal oxides, specifically alkali metal oxides and alkaline earth metal oxides, represent a class of crystalline solid that contains metal cations and oxide anions. Among these metal oxides, magnesium oxide (MgO) has been extensively studied due to its abundantly existing precursors in nature and its applicable physical and chemical properties for water remediation, air emissions treatment, and some medical applications. In the first part of this work, a method of using metal organic frameworks (MOF) as a template material for the synthesis of porous oxide for carbon capture and storage (CCS) was explored to address the overwhelming global climate change issue. Particularly, the solution of how to prevent magnesium oxide particles from sintering during cyclic adsorption and desorption of carbon dioxide (CO2) was inspected. The results showed that a regenerable porous magnesium oxide with high CO2 capture capacity and material regenerability was achieved via this synthesis method. This work suggested that the carbon contents remaining on the surfaces of magnesium oxides may preserve its porous structure and prevent further sintering and structure collapse of the material, evidenced by the adsorbent's retained porosity and capture capacities over repeated carbonation and decarbonation cycles. This demonstration of the synthesis of regenerable metal oxides by thermal decomposition of MOF templates may enable broader applicability for other energy-related metallic oxides. The next part of this work aimed to investigate porous MgO coatings for implants to combat bacterial infections during surgical procedures. In particular, the correlation between surface area/pore volume of obtained MgO and its antibacterial activities was studied. The results of this study suggested that higher surface areas provided better inhibition on both Gram-positive bacteria, methicillin-resistant Staphylococcus aureus and Gram-negative bacteria, Pseudomonas aeruginosa. Those results offered a new perspective to better understand the bacteria-killing mechanism of magnesium oxides and even other metallic oxides.

Gas emission of the motor vehicle is a major contributor to climate change, with a total of 14% emission annually, and the best potential option for reducing pollution is using the adsorption method. Magnesium oxide (MgO) has been proven as an effective adsorbent for liquid and gases. The impregnation of MgO on porous structure increases the affinity toward nonpolar gases, which is one of the purposes of this study. The crystallite structure is also a key factor that determines the adsorption capacity of activated carbon (AC). However, deeper analysis is needed in the activated carbon crystallite structure represented by d002 (aromatic layer), Lc (crystallite height), and La (crystallite diameter) on the adsorption of motor vehicle gas emissions. Three types of palm shell-based activated carbon were tested in this experiment. The results showed that activated carbon made using the two-step method and the AC/MgO produced surface structure with a d002 value of 0.33 nm and 0.32 nm, respectively. The impregnation of MgO on AC showed changes in surface structure and affected its crystallinity. The ability to adsorb CO2 and CO by AC/MgO increase up to 80% and 88%, respectively.

The increment amount of the CO2 emission by years has become a major concern worldwide due to the global warming issue. However, the influence modification of activated carbon (AC) has given a huge revolution in CO2 adsorption capture compare to the unmodified AC. In the present study, the Deep Eutectic Solvent (DES) modified surface AC was used for Carbon Dioxide (CO2) capture in the fixed-bed column. The AC underwent pre-carbonization and carbonization processes at 519.8 °C, respectively, with flowing of CO2 gas and then followed by impregnation with 53.75% phosphoric acid (H3PO4) at 1:2 precursor-to-activant ratios. The prepared AC known as sea mango activated carbon (SMAC) was impregnated with DES at 1:2 solid-to-liquid ratio. The DES is composing of choline chloride and urea with ratio 1:2 choline chloride to urea. The optimum adsorption capacity of SMAC was 33.46 mgco2/gsol and 39.40 mgco2/gsol for DES modified AC (DESAC).

Adsorption of carbon dioxide on hydrotalcite-like compounds of different compositions

Carbon dioxide capture using ammonium sulfate surface modified activated biomass carbon

The potential of direct air capture using adsorbents in cold climates.

Carbon dioxide capture has become an important issue in reducing atmospheric heat these days. In this study, adsorption of carbon dioxide by aerogel Gamma Alumina-Metatitanic Acid has been investigated and optimized. Morphological and structural analyses such as BET, FESEM, FT-IR, and XRD have also been conducted. In addition, Response surface methodology has been applied in order to achieve the optimal conditions, using a five-level Central composite design. The highest amount of adsorption, 12.874 (mmol/g), was recorded at a temperature of 20 (°C), pressure of 7 (bar), and 25 (%wt) of Metatitanic Acid. This was approximately 11.46% and 4.84% higher than those of mesoporous MgO and 4Azeolite, respectively. Regeneration of the adsorbent was also studied at different temperatures and process durations. Metatitanic acid, as a catalyst, reduces the temperature and regeneration time of the adsorbent by creating active sites and surface hydroxyl groups. It also lowers the required activation energy and enhances the thermal conductivity of the composite material. The optimal result was achieved at a temperature of 100 (°C) and a duration of 30 (min). Finally, isothermal and thermodynamic experiments were conducted to establish the most accurate predictive model and conditions, including Enthalpy, Entropy, and Gibbs free energy. The results indicate that the Freundlich model aligned well with the laboratory findings. Additionally, the negative values of Enthalpy, Entropy, and Gibbs free energy suggested that the adsorption process was physical, exothermic, and spontaneous.

Selective adsorption of supercritical carbon dioxide and methane binary mixture in shale kerogen nanopores

Mesoporous magnesium oxide nanoparticles derived via complexation-combustion for enhanced performance in carbon dioxide capture.

According to the present data, KA zeolite, which can adsorb only water vapor, helium, and hydrogen, has the greatest selectivity in drying. The feasibility of using this zeolite in devices for selective drying of gases used in gas-analysis systems was studied. The results of the experiments were approximated by the thermal equation of the theory of bulk filling of micropores. The limiting value of the adsorption depends on the temperature, and it can be calculated according to the density of the adsorbed phase and the adsorption volume. The critical diameters of the water and carbon dioxide molecules are close to the dimensions of the KA-zeolite pores, something that determines the activated nature of the adsorption of these substances. Experiments on coadsorption of water vapor and carbon dioxide by a fixed bed of KA-zeolite under dynamic conditions showed that the adsorption of these substances has a frontal nature. The time of the protective action of the layer of zeolite during adsorption af water vapor exceeded by more than an order the time of the protective action during adsorption of carbon dioxide. The results showed that this adsorbent can be used for selective drying of gas mixtures containing carbon dioxide in batch-operationmore » devices. Beforehand, the adsorbent should be regenerated with respect to moisture, and then it should be saturated with carbon dioxide by blowing the adsorbent with a gas mixture of the working composition until the equilibrium state is reached.« less