CO2 Isotherms Research Articles

Thermodynamic analysis of framework deformation in Na,Cs-RHO zeolite upon CO2 adsorption.

Fully dehydrated and partially sodium-cesium containing RHO zeolite (Na,Cs-RHO) shows a genuine inflection in the CO2 isotherms in the temperature range 293-333 K that can be attributed to a sorbate-induced framework deformation from an acentric (A) to a centric (C) phase due to a partial cation rearrangement. This peculiar sorption pattern can be captured by the formulation of thermodynamic isotherms, providing a direct enthalpic and entropic signature of the CO2 adsorption-desorption process during deformation. Using this formulation, the energy barrier between the acentric and centric phases for CO2 adsorption-desorption was estimated in the range 4.7-9.6 J g(-1) of solid (15-32 kJ mol(-1)), reflecting a higher CO2 affinity for the acentric phase, whereas the elastic energy involved during framework distortion was estimated in the range 6-12 J g(-1) of solid (19-39 kJ mol(-1)) with a relative maximum at 303 K and showing a dominant entropic contribution.

CO2 sorption in wet ordered mesoporous silica kit-6: effects of water content and mechanism on enhanced sorption capacity

The sorption isotherms of CO2 in wet ordered mesoporous silica KIT-6 with different amounts of pre-adsorbed water were firstly collected experimentally using a volumetric method in the temperature range of 275–281 K. The isotherms show an inflection point indicating CO2 hydrates form in the pore spaces which is proofed by the enthalpy change calculated at the inflection pressure, and the quantity of water content shows considerable effect on the sorption capacity of CO2. The highest enhancement of sorption capacity in the presence of water is observed in wet KIT-6 sample with water loadings of 2.48, which is about 12.80 mmol/g and 1.86 times than that on dry sample. However, the saturation capacity is still far less than that what can be stored merely in the form of hydrates due to the low ratio of water utilization because of the large pore and the polar surface of KIT-6.

CO2 adsorption on amine modified mesoporous silicas: Effect of the progressive disorder of the honeycomb arrangement

In this work, we have investigated how the typical honeycomb arrangement of SBA-15 and the mechanisms of CO2 uptake are affected by the addition of chemicals upon synthesis (to modify pore width and length) and post-synthesis amine functionalization. SBA-15 was synthesized hydrothermally by a conventional route (S00) and such synthesis was then subject to modifications: by adding heptane as a swelling agent (S10) and increasing amounts of ammonium fluoride (S11, S12, S13 and S14) to shorten channels length. All of the synthesized silicas were then subject to APTES grafting and PEI impregnation. CO2 isotherms were obtained for the pure and amine-loaded samples. They were fitted to the Dual-Site Langmuir model for all functionalized adsorbents, so that it was possible to discriminate the relative importance of chemisorption and physisorption sites. The increasingly disordered frameworks brought about by fluoride addition led to the formation of mesocellular silica foams (MCFs), which were not advantageous to increase CO2 uptakes in the case of amine-grafting because they have a lower silanol density and hence bind less nitrogen as compared to the conventional SBA-15. In the case of PEI-impregnation, it was found that an addition of a low amount of fluoride is important in the regulation of the chemisorption/physisorption ratio. Promising CO2 uptakes (2.3mmolCO2/g or 4.6mmol/g PEI at 25°C and 1bar) were found for a load of 50% (wt) PEI in MCF synthesized with the highest NH4F/SiO2 molar ratio (equal to 0.065), which was attributed to a better accessibility of amino groups to CO2, as compared to the conventional SBA-15 support subject to the same PEI load.

Borane-modified graphene-based materials as CO2 adsorbents

The authors studied the CO2 adsorption performances of borane modified graphene-based materials (B-rG-O). B-rG-O powder was fabricated by reacting graphene oxide with a borane–THF adduct and showed good CO2 adsorption capacity (1.82mmol/g at 1atm) and recyclability as determined using a CO2 isotherm and breakthrough experiments respectively. The roles of boron moieties for CO2 adsorption were studied using theoretical calculation and spectroscopic experiments.

A 3D Porous Metal Organic Framework Based on Infinite 1D Nickel(II) Chains with Rutile Topology Displaying Open Metal Sites

AbstractThe reaction of NiII with a tetra‐benzoate pyrene ligand produces a 3D porous framework based on infinite 1D NiII chains. The NiII–O connectivity and the formation of a hydroxo‐bridge (μ3‐OH) responsible for the connection of the central NiII atoms within the 1D NiII–(μ3‐OH)2–NiII chains can be straightforwardly compared with the TiIV–O–TiIV connectivity seen in TiO2. The arrangement of the TBAPy ligand around the 1D rutile‐based chains leads in the generation of a porous framework with two distinct types of pores; based on the chemistries of these two types of pores, one can be labelled as hydrophobic and the other as hydrophilic. The use of different activation methods results in the generation of either a porous framework free of guest molecules or a completely solvent‐free material, in which the terminal H2O molecules bound to NiII were removed, leading thus to a framework with open NiII sites. CO2 isotherms collected on both frameworks at 195 K and one barshowed type I isotherms characteristic of microporous materials (BET surface areas for: guest‐free framework: 257(3) m2·g–1; solvent‐free framework: 362(2) m2·g–1). The affinity of both networks at zero coverage for both CO2 and CH4 was found to be greater when the unsaturated NiII sites are available within the void space.

The Role of Carbon Functionalities in the Incorporation of Pseudocapacitive Inorganic Phases for Improved Capacitance

Supercapacitors based on carbon materials have shown high power densities compared to rechargeable batteries, but lower energy densities. The introduction of pseudocapacitive materials, such as conducting polymers and/or different inorganic phases, in different carbons have open the possibility to improve the intrinsic capacitance of the electrode materials, and by consequence the energy densities of the assembled devices. One of the main drawbacks of most inorganic materials is their low electric conductivity, which is somehow compensated when they are incorporated into a carbon matrix. Another strategy has been the introduction of certain functional groups in carbon to promote an intimate interaction with the inorganic compounds, resulting in improved electrochemical properties of the electrode materials for supercapacitors. In these sense, different carbon materials have been modified with different functional groups (-OH, -COOH, -CHO, NH2) to evaluate their effect with different inorganic phases, such as polyoxometalate (POM) or vanadyl phosphate (VOPO4). The resulting nanocomposite materials (C-POM, C-VOPO4) have been characterized by XRD, FTIR, N2 and CO2 isotherms, and most importantly in acidic or neutral aqueous electrolyte where their improved capacitance values have been calculated.

First international inter-laboratory comparison of high-pressure CH4, CO2 and C2H6 sorption isotherms on carbonaceous shales

An inter-laboratory study of high-pressure gas sorption measurements on two carbonaceous shales has been conducted in order to assess the reproducibility of the sorption isotherms and identify possible sources of error. The measurements were carried out by seven international research laboratories using either in-house or commercial sorption equipment (manometric and gravimetric methods). Excess sorption isotherms for methane, carbon dioxide and ethane were measured at 65°C and at pressures up to 25MPa on two organic-rich shales in the dry state. The samples used in this study were taken from immature Posidonia shale (Germany) and over-mature Upper Chokier Formation (Belgium). Their total organic carbon (TOC) contents were 15.1% and 4.4% , respectively, and their vitrinite reflectance (VRr) values 0.5% and 2.0%.The objective of this study was to assess the reproducibility of sorption isotherms among laboratories each following their own measurement and data reduction procedures. All labs were asked to follow a predefined sample drying procedure prior to measurement in order to minimize any effects related to moisture. The reproducibility of the methane excess sorption isotherms was better for the high-maturity shale (within 0.02–0.03mmol/g) than for the low-maturity sample (up to 0.1mmol/g), similar to observations in earlier inter-laboratory studies on coals. The reproducibility for CO2 and C2H6 sorption isotherms was satisfactory at pressures below 5MPa, however, the results deviate considerably at higher pressures. Anomalies in the shape of the excess sorption isotherms were observed for CO2 and C2H6 and these are explained as being due to high sensitivity of gas density to temperature and pressure close to the critical point as well as from a limited measurement accuracy and possibly uncertainty in the equation of state (EoS).The low sorption capacity of carbonaceous shales (as compared to coals and activated carbons) sets very high demands on the accuracy of pressure and temperature measurement and precise temperature control. Furthermore, the sample treatment, measurement and data reduction procedures must be optimized in order to achieve satisfactory inter-laboratory consistency and accuracy. Systematic errors must be minimized first by calibrating the pressure and temperature sensors to high-quality standards. Blank sorption measurements with a non-sorbing sample (e.g. stainless steel) can be used to identify and quantitatively account for measuring artifacts resulting from unknown residual systematic errors or from the limited accuracy of the EoS. The possible sources of error causing the observed discrepancies are discussed.

Utilizing the Gate-Opening Mechanism in ZIF-7 for Adsorption Discrimination between N2O and CO2

N2O is a greenhouse gas with tremendous global warming potential, and more importantly it also causes ozone depletion; thus, the separation of N2O from industrial processes has gained significant attention. We have demonstrated that N2O can be selectively separated from CO2 using the zeolite imidazolate framework ZIF-7. The adsorption/desorption isotherms of both N2O and CO2 in ZIF-7 indicate the gate-opening mechanism of this material, and surprisingly, the threshold pressure for the gate opening with N2O is lower than that with CO2. Theoretical calculations indicate that both gas–host and gas–gas interaction energies for N2O are more favorable than those for CO2, giving rise to the difference in the threshold pressure between N2O and CO2 in ZIF-7. Breakthrough experiments for N2O/CO2 mixtures confirm that ZIF-7 is capable of separating N2O and CO2 mixtures under the optimized conditions, in reasonable agreement with simulation results, making it a promising material for industrial applications.

Transient breakthroughs of CO2/CH4 and C3H6/C3H8 mixtures in fixed beds packed with Ni-MOF-74

The metal-organic framework Ni-MOF-74 was synthesized and then characterized by XRD, SEM, and N2 adsorption techniques. The unary isotherms of CO2, CH4, C3H6, and C3H8 on Ni-MOF-74 were measured by means of a volumetric method. The Langmuir–Freundlich model appropriately describes the adsorption equilibrium data. The selective separations of two mixtures CO2/CH4 and C3H6/C3H8 on Ni-MOF-74 were experimentally investigated by a breakthrough-column technique. Simulations of transient breakthroughs for the two mixtures agree well with the experimental data. In addition, with the inclusion of intra-crystalline diffusion into the simulations, the quality of the simulated breakthrough curves are improved and agree better with the experimental data. The results indicate that Ni-MOF-74 might be a candidate for the removal of C3H6 from C3H6/C3H8 mixtures and for the efficient separation of CO2 from CH4.

Highly Enhanced Selectivity and Easy Regeneration for the Separation of CO2 over N2 on Melamine-Based Microporous Organic Polymers

Melamine based microporous organic polymers (MBMOPs) have been prepared via a one-pot polymerization using the Schiff base reaction. Various techniques such as FT-IR, Ar adsorption, SEM, TEM, and TG have been used to characterize the textural structure, porosity, and stability of the synthesized MBMOPs. The adsorption isotherms of CO2 and N2 on MBMOPs have been accurately measured at pressures up to 118 kPa and different temperatures. Ascribed to the specific affinity of amine groups for CO2, the robust microporous MBMOPs display excellent CO2 adsorption performance in terms of both capacity, up to 2.8 mmol g–1 at 273 K and 118 kPa, and selectivity over N2. Dual-site Langmuir (DSL) or single-site Langmuir (SSL) model describes well the equilibrium data for the adsorption of CO2 or N2 on MBMOPs, respectively. The binary gas adsorption isotherms predicted by the ideal adsorbed solution theory (IAST) show that the prepared MBMOPs exhibit very high selectivities for CO2 over N2, up to 83.7, for equimolar mixtures of CO2 and N2 at 298 K and 100 kPa. The dynamic CO2 adsorption capacity and selectivity against N2 over MBMOPs have been experimentally investigated by breakthrough column technique at 1 bar and 298 K, indicating that a complete separation is available. Remarkably, CO2 capture–regeneration experiments indicate that MBMOPs can be easily regenerated by only purging with He or N2 rather than by raising the temperature, suggesting that MBMOPs are promising candidates of pressure swing adsorption (PSA) adsorbents for the separation of CO2–N2.

Adsorption and Separation of Carbon Dioxide Using MIL-53(Al) Metal-Organic Framework

In this work, we report adsorption isotherms of various industrially important gases, viz. CO2, CO, CH4, and N2 on MIL-53(Al) metal organic framework (MOF). The isotherms were measured in the range of 0–25 bar over a wide temperature range (294–350 K). The structural transformation of the adsorbent and the resulting breathing phenomenon were observed only in the case of CO2 adsorption at 294 and 314 K. Adsorption of CO (another polar gas), N2 and CH4 did not induce any structural transformation in this adsorbent for the experimental conditions considered in this work. Since the CO2 isotherms at 294 and 314 K involve structural transformation and show a distinct step, a conventional isotherm model cannot be used to describe such behavior. In order to model these isotherms, a dual-site Langmuir-type equation (one site each for the two structural forms, i.e., large pore phase and narrow pore phase) that includes a normal distribution function to account for structural transformation is proposed. This model successfully mimics the Type-IV isotherm behavior of CO2 on MIL-53(Al). Henry’s constants and adsorption enthalpies of CO2 on the two structural forms were calculated using this model. The Ideal Adsorbed Solution Theory (IAST) was used to predict the selectivity of CO2 at 350 K over other gases studied in this work.

Calorimetric study of the CO2 adsorption on carbon materials

Given the great interest in the CO2 removal and decreasing their impact on the environment, in this work, a calorimetric study of CO2 adsorption on different activated carbons was performed. For this purpose, we used two methodologies for the determination heat of CO2 adsorption: determination of CO2 isotherms at different temperatures and adsorption calorimetry. The heats determined by these two techniques were compared. In this regard, carbonaceous materials of granular and monolithic types were prepared, characterized, and functionalized for carbon dioxide adsorption. As precursor material, African palm stones that were activated with H3PO4 and CaCl2 at different concentrations was used. The obtained materials were functionalized in gas phase with NH3 and liquid phase with NH4OH, with the intention to incorporate the surface basic groups (amines or nitrogen groups) and subsequently were studied for CO2 adsorption at 273 K and atmospheric pressure. For characterization of these materials, the following techniques are used: N2 adsorption at 77 K and immersion calorimetry in different solvents. The experimental results show the obtaining of micropores and mesoporous (moderately) materials, with surface area between 430 and 1,425 m2 g−1 and pore volumes between 0.17 and 0.53 cm3 g−1. It was determined that there is a difference between the heats of CO2 adsorption obtained by the techniques employed. This deviation between the values corresponds to the methodological difference between the two experiments. In this work, we obtained a maximum adsorption capacity of CO2, which is greater than 334 mg CO2 g−1 at 273 K and 1 bar in carbon materials with moderate surface area and pores volume.

Preparation and Adsorption Performance of GrO@Cu-BTC for Separation of CO2/CH4

Composites (GrO@Cu-BTC) based on Cu-BTC and graphene oxide were synthesized by a solvothermal method for the separation of CO2/CH4 binary mixtures. The as-synthesized composites were then characterized. The isotherms of CO2 and CH4 on the as-synthesized materials were measured by the volumetric method. The isotherms and adsorption selectivities of CO2/CH4 binary mixtures were estimated on the basis of ideal adsorbed solution theory (IAST). The results showed that the composite 1GrO@Cu-BTC had a higher BET surface area and pore volume compared to the parent Cu-BTC. More importantly, its adsorption capacity for CO2 improved significantly in comparison with that of Cu-BTC, which was up to 8.19 mmol/g at 1 bar and 273 K. The dual-site Langmuir–Freundlich (DSLF) model was applied favorably for fitting experimental isotherm data of CO2 and CH4 adsorption on the samples. The predicted isotherms of the binary mixture based on IAST showed that CO2 was more favorably adsorbed than CH4 on the sample 1GrO@Cu-BTC. TPD...

Theoretical investigations of CO₂ and CH₄ sorption in an interpenetrated diamondoid metal-organic material.

Grand canonical Monte Carlo (GCMC) simulations of CO2 and CH4 sorption and separation were performed in dia-7i-1-Co, a metal–organic material (MOM) consisting of a 7-fold interpenetrated net of Co2+ ions coordinated to 4-(2-(4-pyridyl)ethenyl)benzoate linkers. This MOM shows high affinity toward CH4 at low loading due to the presence of narrow, close fitting, one-dimensional hydrophobic channels—this makes the MOM relevant for applications in low-pressure methane storage. The calculated CO2 and CH4 sorption isotherms and isosteric heat of adsorption, Qst, values in dia-7i-1-Co are in good agreement with the corresponding experimental results for all state points considered. The experimental initial Qst value for CH4 in dia-7i-1-Co is currently the highest of reported MOM materials, and this was further validated by the simulations performed herein. The simulations predict relatively constant Qst values for CO2 and CH4 sorption across all loadings in dia-7i-1-Co, consistent with the one type of binding site identified for the respective sorbate molecules in this MOM. Examination of the three-dimensional histogram showing the sites of CO2 and CH4 sorption in dia-7i-1-Co confirmed this finding. Inspection of the modeled structure revealed that the sorbate molecules form a strong interaction with the organic linkers within the constricted hydrophobic channels. Ideal adsorbed solution theory (IAST) calculations and GCMC binary mixture simulations predict that the selectivity of CO2 over CH4 in dia-7i-1-Co is quite low, which is a direct consequence of the MOM’s high affinity toward both CO2 and CH4 as well as the nonspecific mechanism shown here. This study provides theoretical insights into the effects of pore size on CO2 and CH4 sorption in porous MOMs and its effect upon selectivity, including postulating design strategies to distinguish between sorbates of similar size and hydrophobicity.

Sorption of CH4 and CO2 on a carboniferous shale from Belgium using a manometric setup

Shale gas resources are globally abundant, and the development of these resources can increase CH4 production. It is of interest to study the possibility of enhancing CH4 production by CO2 injection (enhanced gas recovery—EGR). Some studies indicate that, in shale, five molecules of CO2 can be stored for every molecule of CH4 produced. The technical feasibility of enhanced gas recovery (EGR) needs to be investigated in more detail. The amount of extracted natural gas from shale has increased rapidly over the past decade. A typical shale gas reservoir combines an organic-rich deposition with extremely low matrix permeability. One important parameter in assessing the technical viability of (enhanced) production of shale gas is the sorption capacity. Our focus is on the sorption of CH4 and CO2. Therefore, we have chosen to use the manometric method to measure the excess sorption isotherms of CO2 at 318K and of CH4 at 308, 318 and 336K and at pressures up to 105bar on Belgium dry black shale from a depth of 745m. The shale was obtained from the former coal mine in Zolder in the Campina Basin (North Belgium), which contains Westphalian coal and coal associated sediments of Northwest European origin. We derive the equations for excess sorption in the manometric setup. Only a few measurements have been reported in the literature for high-pressure gas sorption on shales, and interest is largely focused on shales occurring outside Europe. The excess sorption isotherm shows an initial increase to a maximum value of 0.175±0.004mmol/gram for CO2 and then starts to decrease until it becomes zero at 82bar and subsequently the excess sorption becomes negative. Similar behaviour was also observed for other shales and coal reported in the literature. The experiments on CH4 show, as expected, decreasing sorption for increasing temperature. We apply an error analysis based on the Monte Carlo simulation. It shows that the error is increasing with increasing pressure, but that the manometric setup can be used to determine the sorption capacity of CO2 and CH4 on the black shale with sufficient accuracy.

Conformation-Controlled Sorption Properties and Breathing of the Aliphatic Al-MOF [Al(OH)(CDC)

The Al-MOF CAU-13 ([Al(OH)(trans-CDC)]; trans-H2CDC = trans-1,4-cyclohexanedicarboxylic acid) is structurally related to the MIL-53 compounds that are well-known for their "breathing" behavior, i.e., the framework flexibility upon external stimuli such as the presence of adsorbate molecules. The adsorption properties of CAU-13 were investigated in detail. The sorption isotherms of N2, H2, CH4, CO, CO2, and water were recorded, and the adsorption enthalpies for the gases were determined by microcalorimetry. The structural changes upon adsorption of CO2 were followed with in situ synchrotron powder X-ray diffraction (PXRD). The patterns were analyzed by parametric unit cell refinement, and the preferential arrangement of the CO2 molecules was modeled by density functional theory calculations. The adsorption and separation of mixtures of o-, m-, and p-xylene from mesitylene showed a preferred adsorption of o-xylene. The structures of o/m/p-xylene-loaded CAU-13 were determined from PXRD data. The adsorption of xylene isomers induces a larger pore opening than that in the thermal activation of CAU-13. In the crystal structure of the activated sample CAU-13(empty pore), half of the linkers adopt the a,a confirmation and the other half the e,e conformation, and the presence of a,a-CDC(2-) ions hampers the structural flexibility of CAU-13. However, after the adsorption of xylene, all linkers are present in the e,e conformation, allowing for a wider pore opening by this new type of "breathing".

Monte Carlo Modeling of Carbon Dioxide Adsorption in Porous Aromatic Frameworks

The adsorption isotherms of CO2 in several porous aromatic frameworks (PAFs) have been simulated with Grand Canonical Monte Carlo technique, to support the synthesis of new materials for efficient carbon dioxide capture and storage. The simulations covered the 0-60 bar pressure range and were repeated at 273, 298, and 323 K. The force field employed in the simulations was optimized to fit the correct behavior of the free gas and to reproduce the CO2-phenyl interactions computed at high quantum mechanical level. PAFs are based on the diamond structure, with polyaromatic chains inserted in C-C bonds. We examined four PAF-30n (n being the number of phenyl rings in the aromatic linkers), finding that PAF-302 is overall the best performing, although PAF-301 provides higher adsorbed densities at very low pressure. The CO2 adsorption then was simulated in a number of modified PAF-302, with different functional groups (aminomethane, toluene, pyridine, and imidazole) attached to the phenyl chains; different degrees of substitution (25%, 50%, and 100% derivatized rings) were considered. The effects of functionalization and the dependence on the substitution degree are carefully discussed, to determine the most promising materials at low, intermediate, and high pressures.

Adsorption isotherms of CO2, CO, N2, CH4, Ar and H2 on activated carbon and zeolite LiX up to 1.0 MPa

The adsorption isotherms of CO2, CO, N2, CH4, Ar, and H2 on activated carbon and zeolite LiX were measured using a volumetric method. Equilibrium experiments were conducted at 293, 308, and 323 K and pressures up to 1.0 MPa. The adsorption isotherm and heat of adsorption were analyzed for two pressure regions of experimental data: pressures up to 0.1 MPa and up to 1.0 MPa. Each experimental isotherm was correlated by the Langmuir, Sips, Toth and temperature dependent Sips isotherm models, and the deviation of each model was evaluated. The Sips and Toth models showed smaller deviation from the experimental data of adsorbents than the Langmuir model. Isosteric heats of adsorption were calculated by the temperature dependent Sips model and are presented along with surface loading. From deviation analysis, it is recommended that the isotherm in the proper pressure range be used to appropriately design adsorptive processes.

Force-Field Development from Electronic Structure Calculations with Periodic Boundary Conditions: Applications to Gaseous Adsorption and Transport in Metal-Organic Frameworks.

We present a systematic and efficient methodology to derive accurate (nonpolarizable) force fields from periodic density functional theory (DFT) calculations for use in classical molecular simulations. The methodology requires reduced computation cost compared with other conventional ways. Moreover, the whole process is performed self-consistently in a fully periodic system. The force fields derived by using this methodology nicely predict the CO2 and H2O adsorption isotherms inside Mg-MOF-74, and is transferable to Zn-MOF-74; by replacing the Mg-CO2 interactions with the corresponding Zn-CO2 interactions, we obtain an accurate prediction of the corresponding isotherm. We have applied this methodology to address the effect of water on the separation of flue gases in these materials. In general, the mixture isotherms of CO2 and H2O calculated with these derived force fields show a significant reduction in CO2 uptake with the existence of trace amounts of water vapor. The effect of water, however, is found to be quantitatively different between Mg- and Zn-MOF-74.

Description of gas adsorption isotherms on activated carbons with heterogeneous micropores using the Dubinin–Astakhov equation

Activated carbons with heterogeneous micropores were prepared from moso bamboo via KOH activation in this study. Due to a high degree of burn-off during KOH activation, the Dubinin–Astakhov (D-A) equation that contains an empirical parameter n was proposed to describe adsorption isotherms in terms of micropore filling, which could highlight the increased surface heterogeneity. The characteristic curves revealed that at low relative pressures the fraction of micropore filling was higher with decreasing n value. The adsorption isotherms of CO2 on the activated carbons prepared in this work at 273K, 298K, and 313K were satisfactorily described by the D-A equation with a correlation coefficient r2 higher than 0.999. The characteristic energy of adsorption of 4.08kJ/mol and a value of n of 1.0 demonstrated that the adsorption of CO2 on the moso bamboo-derived activated carbons was in agreement with the characteristic curves of the D-A equation.