Hierarchical porous nitrogen-doped carbon materials derived from one-step carbonization of polyimide for efficient CO<Subscript>2</Subscript> adsorption and separation

Hierarchical porous nitrogen-doped carbon (HPNC) materials are synthesized through one-step carbonization of polyimide using triblock copolymer P123 as mesoporous template. The microstructure, chemical composition and CO₂ adsorption behaviors are investigated in detail. The results show that HPNC materials have hierarchical micro-/mesopore structures, high specific surface area of 579 m²/g, large pore volume of 0.34 cm³/g, and nitrogen functional groups (5.2 %). HPNC materials exhibit high CO₂ uptake of 5.56 mmol/g at 25 °C and 1 bar, which is higher than those of previously reported nitrogen-doped porous carbon materials. After 5 cycles the value of CO₂ adsorption uptakes is 5.28 mmol/g, which is approximately 95 % of the original adsorption capacity. The estimated CO₂/N₂ selectivity of HPNC materials is 17, revealing great promise for practical CO₂ adsorption and separation applications. The efficient CO₂ uptake and enhanced CO₂/N₂ selectivity are due to the combination of nitrogen-doped and hierarchical porous structures of HPNC materials.     

Preparation of amine-modified SiO<Subscript>2</Subscript> aerogel from rice husk ash for CO<Subscript>2</Subscript> adsorption

Amine-modified SiO₂ aerogel was prepared using 3-(aminopropyl)triethoxysilane (APTES) as the modification agent and rice husk ash as silicon source, its CO₂ adsorption performance was investigated. The amine-modified SiO₂ aerogel remains porous, the specific surface area is 654.24 m²/g, the pore volume is 2.72 cm³/g and the pore diameter is 12.38 nm. The amine-modified aerogel, whose N content is up to 3.02 mmol/g, can stay stable below the temperature of 300 °C. In the static adsorption experiment, amine-modified SiO₂ aerogel (AMSA) showed the highest CO₂ adsorption capacity of 52.40 cm³/g. A simulation was promoted to distinguish the adsorption between the physical process and chemical process. It is observed that the chemical adsorption mainly occurs at the beginning, while the physical adsorption affects the entire adsorption process. Meanwhile, AMSA also exhibits excellent CO₂ adsorption–desorption performance. The CO₂ adsorption capacity dropped less than 10 % after ten times of adsorption–desorption cycles. As a result, AMSA with rice husk ash as raw material is a promising CO₂ sorbent with high adsorption capacity and stable recycle performance and will have a broad application prospect for exhaust emission in higher temperature.     

Greenhouse Gas Adsorptivity of Horn-Shaped Carbon Nanotubes over Nitrogen: Equilibrium Study

The synthesis of horn-shaped carbon nanotubes using carbon tetrachloride as carbon source was carried out by solvothermal method at 200°C for 2 h. The scanning and transmission electron microscopic characterization of the obtained product showed the formation of horn-shaped carbon nanotubes with irregular wall structure having inner diameter of ～105 nm and length of ～1 µm. The equilibrium gas adsorption properties of horn-shaped carbon nanotubes derived from carbon tetrachloride were successfully investigated for CO₂, CH₄, and N₂ at 288, 303, and 318 K. Horn-shaped carbon nanotubes possess better CO₂ adsorption capacity (2.53 mmol/g) with high capacity selectivity (14.7) and equilibrium selectivity (59.1) over N₂ at 288 K. The detailed adsorption study with estimation of physical parameters such as Henry's constant and heat of adsorption identifies the horn-shaped carbon nanotubes as a potential adsorbent material in the field of CO₂ storage and separation.     

Complexity of CO2 adsorption on nanoporous sulfur-doped carbons – Is surface chemistry an important factor?

Nanoporous S-doped carbon and its composites with graphite oxide were tested as adsorbents of CO₂ (1 MPa at 0 °C) after degassing either at 120 °C or 350 °C. The adsorption capacities were over 4 mmol/g at ambient pressure and 8 mmol/g at 0.9 MPa in spite of a low volume of micropores. The nitrogen adsorption experiments showed an increase in porosity upon an increase in the degassing temperature. The extent of this effect depends on the stability of surface groups. Interestingly, the CO₂ adsorption, especially at low pressure, was not affected. The good performance is due to the presence of ultramicropores similar in sizes to CO₂ molecule and to sulfur in various functionalities. Sulfur incorporated to aromatic rings enhances CO₂ adsorption via acid–base interactions in micropores. Moreover, sulfonic acids, sulfoxides and sulfones attract CO₂ via polar interactions. Hydrogen bonding of CO₂ with acidic groups on the surface can also play an important role in the CO₂ retention. These carbons have high potential for application as CO₂ removal media owing to their high degree of pore space utilization. The results obtained also show that high degassing temperatures might result in the decomposition of surface groups and thus in changes in surface interactions.     

Adsorption of CO<Subscript>2</Subscript> by iron-exchanged heteropolyacid Fe<Subscript>1.5</Subscript>PMo<Subscript>12</Subscript>O<Subscript>40</Subscript> supported on mesoporous cellular foams

Novel low-temperature swing adsorbents that preferably adsorb CO₂ were synthesized by varying loading of heteropolyacid Fe_1.5PMo₁₂O₄₀ (Fe–PMA) supporting on mesoporous cellular foams (MCFs) by wetting impregnation. The synthesized materials were characterized by various physicochemical, thermal and spectral techniques and the CO₂ adsorption capacity of the materials were evaluated. Solid adsorbents showed a significantly high adsorption capacity toward CO₂ due to the chemisorptions of CO₂. The CO₂ adsorption capacities of the materials decreased as the temperature increased. The results showed that the adsorption capacity reached a level of 81.8 mg CO₂/g-adsorbent at 25 °C for the 20 wt% Fe–PMA–MCFs. These results indicated that the iron (Fe²⁺) complexes acted as efficient catalysts for the separation of CO₂. The as-synthesized adsorbents were selective, thermally stable, long-lived, and could be recycled at a temperature of 110 °C.     

H2, CO2, and CH4 Adsorption Potential of Kerogen as a Function of Pressure,Temperature, and Maturity

We performed molecular dynamics simulation to elucidate the adsorption behavior of hydrogen (H₂), carbon dioxide (CO₂), and methane (CH₄) on four sub-models of type II kerogens (organic matter) of varying thermal maturities over a wide range of pressures (2.75 to 20 MPa) and temperatures (323 to 423 K). The adsorption capacity was directly correlated with pressure but indirectly correlated with temperature, regardless of the kerogen or gas type. The maximum adsorption capacity was 10.6 mmol/g for the CO₂, 7.5 mmol/g for CH₄, and 3.7 mmol/g for the H₂ in overmature kerogen at 20 MPa and 323 K. In all kerogens, adsorption followed the trend CO₂ > CH₄ > H₂ attributed to the larger molecular size of CO₂, which increased its affinity toward the kerogen. In addition, the adsorption capacity was directly associated with maturity and carbon content. This behavior can be attributed to a specific functional group, i.e., H, O, N, or S, and an increase in the effective pore volume, as both are correlated with organic matter maturity, which is directly proportional to the adsorption capacity. With the increase in carbon content from 40% to 80%, the adsorption capacity increased from 2.4 to 3.0 mmol/g for H₂, 7.7 to 9.5 mmol/g for CO₂, and 4.7 to 6.3 mmol/g for CH₄ at 15 MPa and 323 K. With the increase in micropores, the porosity increased, and thus II-D offered the maximum adsorption capacity and the minimum II-A kerogen. For example, at a fixed pressure (20 MPa) and temperature (373 K), the CO₂ adsorption capacity for type II-A kerogen was 7.3 mmol/g, while type II-D adsorbed 8.9 mmol/g at the same conditions. Kerogen porosity and the respective adsorption capacities of all gases followed the order II-D > II-C > II-B > II-A, suggesting a direct correlation between the adsorption capacity and kerogen porosity. These findings thus serve as a preliminary dataset on the gas adsorption affinity of the organic-rich shale reservoirs and have potential implications for CO₂ and H₂ storage in organic-rich formations.     

Effects of different structure-directing agents (SDA) in MCM-41 on the adsorption of CO2

CO₂ capturing technologies have attracted significant attention in order to limit emissions and reduce their negative effect on the environment. Mesoporous silica materials (MCM-41) are easily recyclable, affordable, and thermally and mechanically stable, providing added benefits in CO₂ capture. However, further studies are necessary to characterize the effects of MCM-41 pore size, adsorption temperature and surface silylation on CO₂ adsorption efficiency. In this work, mesoporous silica is synthesized using alkyltrimethylammonium bromide with different chain lengths (C_nH_2n + 1 N(CH₃)₃Br, n = 14, 16 and 18) as structure-directing agents, and the adsorption capacity of CO₂ on TTMCM-41 (C₁₇H₃₈NBr), CTMCM-41 (C₁₉H₄₂NBr), DTMCM-41(C₂₁H₄₆NBr) samples was measured gravimetrically at room temperature and pressure up to 40 bar. The silica structures were characterized by X-ray diffraction (XRD), nitrogen adsorption/desorption, Fourier transform infrared spectroscopy, thermogravimetric analysis, scanning electron microscopy and transmission electron microscopy (TEM). The XRD, N₂ adsorption–desorption and TEM measurements indicated the presence of a well-ordered hexagonal array with uniform mesostructures. The mesoporous silica obtained, denoted as TTMCM-41, CTMCM-41 and DTMCM-41, had distinct physical properties, such as BET surface area, hexagonal unit cell, pore volume, pore diameter and pore wall thickness. CTMCM-41 exhibited an adsorption capacity (0.58 g CO₂/g adsorbent) of more than DTMCM-41 (0.48 g CO₂/g adsorbent) and TTMCM-41 (0.42 g CO₂/g adsorbent). The results suggest that CTMCM-41 can be a better mesoporous adsorbent for CO₂ adsorption .     

Dynamic CO2 adsorption performance of internally cooled silica‐supported poly(ethylenimine) hollow fiber sorbents

The dynamic adsorption behavior of CO₂ under both nonisothermal and nearly isothermal conditions in silica supported poly(ethylenimine) (PEI) hollow fiber sorbents (Torlon®‐S‐PEI) is investigated in a rapid temperature swing adsorption (RTSA) process. A maximum CO₂ breakthrough capacity of 1.33 mmol/g‐fiber (2.66 mmol/g‐silica) is observed when the fibers are actively cooled by flowing cooling water in the fiber bores. Under dry CO₂ adsorption conditions, heat released from the CO₂‐amine interaction increases the CO₂ breakthrough capacity by reducing the severity of the diffusion resistance in the supported PEI. This internal resistance can also be alleviated by prehydrating the fiber sorbent with a humid N₂ feed. The CO₂ breakthrough capacity of prehydrated fibers is adversely affected by the release of the adsorption enthalpy (unlike the dry fibers); however, active cooling of the fiber results in a constant CO₂ breakthrough capacity even at high CO₂ delivery rates (i.e., high adsorption enthalpy delivery rates). In full RTSA cycles, a purity of 50% CO₂ is achieved and the adsorption enthalpy recovery rate can reach ～72%. Studies on the cyclic stability of uncooled fiber sorbents in the presence of SO₂ and NO contaminants indicate that exposure to NO at 200 ppm over 120 cycles does not lead to a significant degradation of the sorbents, but SO₂ exposure at a similar high concentration of 200 ppm causes 60% loss in CO₂ breakthrough capacity after 120 cycles. A simple amine reinfusion technique is successfully demonstrated to recover the adsorption capacity in poisoned fiber sorbents after deactivation by exposure to impurities such SO₂. © 2014 American Institute of Chemical Engineers AIChE J, 60: 3878–3887, 2014     

Adsorption of carbon dioxide and water vapor on fly-ash based ETS-10

CO₂ capture from humid flue gas is always costly due to the irreplaceable pretreatment of dehydration in current processes, which creates an urgent demand for moisture-insensitive adsorbents with considerable CO₂ uptakes as well as remarkable H₂O tolerances. In the present work, the microporous titanium silicate molecular sieve ETS-10 was synthesized with coal fly ash as the only silica source. The as-synthesized ETS-10 was characterized by X-ray diffraction, scanning electronic microscopy and infrared spectroscopy to verify its crystal morphology, in which neither impurity nor aggregation was observed. The following CO₂ adsorption experiments on the thermal gravimetric analyzer demonstrated its similar CO₂ adsorption capacity yet dramatical adsorption kinetics among some other microporous materials, e.g., potassium chabazite. These specific properties consequently guaranteed its favorable CO₂ adsorption capacity even at high temperatures (1.35 mmol/g at 393 K) and shortened the breakthrough time of single CO₂ flow to less than 20 s. In CO₂/H₂O binary breakthrough experiments, the as-obtained ETS-10 still maintained excellent CO₂ uptake of 0.81 mmol/g at 323 K, regardless of the presence of water vapor, making it a promising substitute for direct CO₂ separation from humid flue gases at practical conditions of post-combustion adsorption.     

Wastewater Treatment by Chemically Activated Carbons from Giant Reed: Effect of the Activation Atmosphere on Properties and Adsorptive Behavior

Abstract

Uptake of nickel and benzene from dilute single‐solute solutions, mimicking wastewater with low concentrations of heavy metals or volatile organic compounds, was examined using activated carbons with similar good surface properties (BET surface area of ≈1100 m²/g). They were developed through H₃PO₄ acid activation of giant reed (Arundo donax L.) under flowing air or N₂. The carbons obtained in air proved more effective to capture Ni(II) ions under pre‐established equilibrium conditions. Inversely, the N₂‐derived carbons exhibited a better ability for benzene adsorption. The behavior was related to the smaller total content of acidic/polar surface oxygen functionalities of the carbons developed under N₂ (1.9 meq/g), compared to that of the air‐derived ones (3.3 meq/g). Two‐, three‐parameter models described properly the isotherms, predicting similar maximum adsorption capacities (X_m ) for the investigated systems. The X_m parameter in the Langmuir's model was 0.44 mmol/g for the adsorption of Ni(II) ions on the air‐derived carbons, and 0.45 mmol/g for benzene adsorption on those obtained in N₂. Present results highlight the relevance of the surface chemistry developed upon activation to optimize the performance of activated carbons for wastewater treatment according to the pollutants' nature.     

CO2 capture of amino functionalized three-dimensional worm-hole mesostructured MSU-J silica

Tetraethylenepentamine (TEPA) was employed to functionalize the large-pore mesoporous silica (denoted MSU-J) with 3D worm-hole framework structures which was prepared through a supramolecular hydrogen-bonding assembly pathway from low-cost H₂NCH(CH₃)CH₂[OCH₂CH(CH₃)]₃₃NH₂ (D2000) as structure-directing porogens and tetraethylorthosilioate as the silica source for capturing CO₂. The resultant adsorbents were characterized by FT-IR, Transmission electron microscopy (TEM), N₂ adsorption/desorption and thermogravimetric analysis. Textural properties, elemental analysis and TEM measurement of the samples showed a severe pore filling of MSU-J as TEPA loading was increased to 70 wt%. CO₂ adsorption isotherms measured at different temperatures revealed the optimal adsorption temperature is 25 °C. The adsorption capacity of MSU-J with different TEPA loading contents was calculated. As a result, 50 wt% of TEPA supported on as-synthesized MSU-J achieved the highest capacity with the value of 164.3 mg/g under the conditions of 99.99 % CO₂ at 25 °C and 0.1 MPa. Repeated adsorption/desorption cycles revealed that amine-impregnated materials was very efficient for less apparent decrease in CO₂ adsorption capacity even after 6 adsorption–regeneration cycles.     

Facile synthesis of amine-functionalized MIL-53(Al) by ultrasound microwave method and application for CO<Subscript>2</Subscript> capture

An amine functional MIL-53(Al) material was prepared through a clean, rapid, energy-efficient method of microwave and ultrasound irradiation. The pure phase NH₂-MIL-53(Al) can be formed in 25 min, utilizing the synergistic effect of microwave and ultrasound irradiation. The dramatic acceleration in reaction rates suggested that the removal of a passivation coating on the substrate particles and the resultant enhancement in mass and heat transfer. The porous MOFs exhibited a high thermal and chemical stability, decomposing at temperatures above 410 °C in air. The NH₂-MIL-53(Al) performed an excellent adsorption for CO₂. The CO₂ capacities up to 33.86 cm³ g^?1 at 298 K at low pressures, which suggests chemisorption between CO₂ and pendan amine groups. Measurement of CO₂ adsorption cycles proved that the functionalized materials show good regenerability and stability.     

N‐doped porous carbons for CO2 capture: Rational choice of N‐containing polymer with high phenyl density as precursor

N‐doped porous carbons (NPCs) are highly promising for CO₂ capture, but their preparation is severely hindered by two factors, namely, the high cost of N‐containing polymer precursors and the low yield of carbon products. Here we report for the first time the fabrication of NPCs through the rational choice of the polymer NUT‐4, with low cost and high phenyl density, as precursor. For the material NPC‐600 obtained from carbonization at 600°C, the yield is as high as 52.1%. The adsorption capacity of CO₂ on NPC‐600 reaches 6.9 mmol/g at 273 K and 1 bar, which is obviously higher than that on the benchmarks, including 13X zeolite (4.1 mmol/g) and activated carbon (2.8 mmol/g), as well as most reported carbon materials. Our results also demonstrate that the present NPCs can be completely regenerated under mild conditions. The abundant microporosity and “CO₂‐philic” (N‐doped) sites are responsible for the adsorption performance. © 2016 American Institute of Chemical Engineers AIChE J, 63: 1648–1658, 2017     

Aminating modification of viscose fibers and their CO2 adsorption properties

An adsorbent for CO₂ capture was prepared by the grafting of acrylonitrile (AN) onto viscose fibers (VFs); this was followed by amination with triethylene tetramine (TETA). The effects of the reaction conditions, such as the concentrations of the monomer, initiator, and nitric acid, on the grafting degree and grafting efficiency were studied. The adsorption performance of the adsorbent for CO₂ was evaluated by fixed‐bed adsorption. The highest dynamic adsorption capacity of the adsorbent for CO₂ was 4.35 mmol/g when the amine content of the adsorbent VF–AN–TETA reached 13.21 mmol/g. Compared with the polypropylene (PP)‐fiber‐based adsorbent (PP–AN–TETA), VF–AN–TETA with hydroxyl groups on the fibers facilitated the diffusion of CO₂ and water and led to a higher CO₂ adsorption capacity than that of PP–AN–TETA. The VF–AN–TETA adsorbent also showed good regeneration performance: its CO₂ adsorption capacity could still retain almost the same capacity as the fresh adsorbent after 10 adsorption–desorption cycles. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 132, 42840.     

Porous carbonaceous materials from hydrothermal carbonization and KOH activation of corn stover for highly efficient CO2 capture

Sustainable biomass-derived carbon materials were produced by hydrothermal carbonization of corn stover that was followed by chemical activation with KOH. The prepared carbon materials were used for CO₂ adsorption and had a CO₂ uptake of 7.14?mmol/g at a pressure of 1?bar and at 0°C that was much higher than CO₂ uptake by activated carbon that was prepared from direct activation of corn stover (2.78?mmol/g). The porous corn stover-derived carbonaceous material had high surface area (2442?m²/g) and large pore volume (1.55?cm³/g). Product yields obtained by the activation of hydrothermally carbonized corn stover were significantly higher than those obtained by the direct activation of corn stover (36–75?vs. 8%). The prepared corn stover-derived porous carbon had a high CO₂/N₂ selectivity of 15.5 and exhibited constant CO₂ uptake for five successive reuse cycles. The hydrothermal carbonization step plays an important role for producing porous carbons from biomass that have high and specific adsorption properties.     

Chemical activation of mesoporous carbon with ultrahigh pore volume for highly supported adsorption of CO<Subscript>2</Subscript>

A novel mesoporous carbon (AMC850) with worm-like mesoporosity, very large BET surface area (2935 m²/g), and ultrahigh pore volume of 3.41 cm³/g was facilely synthesized from etching of the pristine mesoporous carbon (MC850) with sodium amide (NaNH₂). The mesoporosity in the synthesized AMC850 was significantly expanded in comparison with pristine mesoporous carbon. The synthesized AMC850acts as an efficient support, could accommodate much more pentaethylenehexamine (PEHA) in comparison with the pristine MC850, giving PEHA@AMC850 composites. The resultant PEHA@AMC850 showed much improved property for the selective capture of CO₂ in comparison with AMC850 (2.02 mmol/g vs. 0.73 mmol/g, at 75 °C). Thus, the PEHA@AMC850 composites showed promising application in the selective capture of CO₂ from flue gas.     

CO2 Adsorption by Modified Palm Shell Activated Carbon (PSAC) Via Chemical and Physical Activation and Metal Impregnation

The aim of this study was to verify the ability of nickel-impregnated palm shell activated carbon (PSAC) for CO₂ adsorption and compare its performance with the chemically and physically activated PSAC. Sodium hydroxide and CO₂ were used as activating agents for chemical and physical activation, respectively. Nickel nitrate hexahydrate (Ni(NO₃)₂·6H₂O) was used as a precursor for metal impregnation. The effect of different chemical loadings (NaOH: 20–50 wt%), metal impregnation (Ni(NO₃)₂·6H₂O: 16–28 wt%), and heat treatment time (1–4 h) was studied as parameters. Adsorption capacity was calculated using breakthrough graphs. The effect of humidity on CO₂ adsorption and desorption of CO₂ was also investigated in this study. The results revealed that chemically modified PSAC yields the highest adsorption capacity (48.2 mg/g) compared to other methods of activation. Interestingly, it was found that the adsorption capacity of nickel-impregnated PSAC was similar to other types of metal-impregnated activated carbon. Humidity gave a negative effect on CO₂ adsorption. In summary, results showed that chemical activation is an efficient technique to modify PSAC for CO₂ adsorption.     

Nanoporous rice husk derived carbon for gas storage and high performance electrochemical energy storage

We report on the gas storage behaviour and electrochemical charge storage properties of high surface area activated nanoporous carbon obtained from rice husk through low temperature chemical activation approach. Rice husk derived porous carbon (RHDPC) exhibits varying porous characteristics upon activation at different temperatures and we observed high gas uptake and efficient energy storage properties for nanoporous carbon materials activated even at a moderate activation temperature of 500 °C. Various experimental techniques including Fourier transform-infrared spectroscopy, Raman spectroscopy, scanning electron microscopy, high resolution transmission electron microscopy and pore size analyser are employed to characterise the samples. Detailed studies on gas adsorption behaviour of CO₂, H₂ and CH₄ on RHDPCs have been performed at different temperatures using a volumetric gas analyser. High adsorption capacities of ~9.4 mmol g^?1 (298 K, 20 bar), 1.8 wt% (77 K, 10 bar) and ~5 mmol g^?1 (298 K, 40 bar) were obtained respectively for CO₂, H₂ and CH₄, superior to many other carbon based physical adsorbents reported so far. In addition, these nanoporous carbon materials exhibit good electrochemical performance as supercapacitor electrodes and a maximum specific capacitance of 112 F g^?1 has been obtained using aqueous 1 M Na₂SO₄ as electrolyte. Our studies thus demonstrate that nanoporous carbon with high porosity and surface area, obtained through an efficient approach, can act as effective materials for gas storage and electrochemical energy storage applications.     

Arsenic removal from water by photocatalytic functional Fe<Subscript>2</Subscript>O<Subscript>3</Subscript>–TiO<Subscript>2</Subscript> porous ceramic

Fe₂O₃–TiO₂ porous ceramic (Fe/TiPC) beads with photo-catalytic performances and high adsorption capacities were prepared by a simple high temperature solid reaction and were applied for arsenic removal from drinking water. The microstructure and morphology of Fe/TiPC were characterized by X-ray diffraction and scanning electron microscopy. More than 90% removal ratio for As (III) and As (V) were respectively achieved by Fe/TiPC within 2 h under UV irradiation. The Langmuir capacity values of Fe/TiPC for As (III) and As (V) were 13.86 and 15.73 mg/g, respectively. In addition, Fe/TiPC could be reused for up to five times without significant reduction in the photocatalytic sensitivity and adsorption capacity aspects. Good catalytic oxidation performances and high adsorption capacities as well as a sample preparation for Fe/TiPC suggest that the composites may have practical prospects for the As (III) and As (V) removal from contaminated water.     

Effects of exchanged ammonium cations on structure characteristics and CO2 adsorption capacities of bentonite clay

Different alkali and alkaline earth cation forms of bentonite clay were exchanged with protonated mono-, di- and triethanolamine compounds, to study the effect of the exchanged ammonium cations on the structure characteristics, thermal behavior, surface properties and CO₂ adsorption capacities of bentonite clay. The revolution of the interlayer structure characteristics, thermal properties, the specific surface area and elemental analysis were characterized by XRD, FTIR, TGA, BET and CHNS techniques respectively, while the CO₂ adsorption capacities were gravimetrically measured by using magnetic suspension balance (MSB) equipment. It was found that the intercalation of ammonium cations into the interlayer space of bentonite clay induced a step change in its basal spacing, depending on their molar mass and the interlayer molecular arrangement. The presence of the characteristic IR peaks of amine compounds in the spectra of bentonite clay adsorbents modified by amines was qualitatively supported by the incorporation of ammonium cations in the interlayer space of bentonite, while the presence of C, H and N elements using CHNS technique was quantitatively confirmed by the intercalation process of amine compounds. It was also found that the molar mass of amines has an inverse effect on the amount of the adsorbed water (intensity), its desorption temperature (position) and the specific surface area of the synthesized materials. The CO₂ adsorption capacities on all the studied bentonite clay adsorbents modified by amines were found to increase between 2.68 and 3.15 mmol/g, compared to 0.93 mmol/g for untreated bentonite at the studied temperature and pressure. As expected, bentonite clay modified with di- and triethanolammonium cations showed lower CO₂ adsorption capacities than that treated with monoethanolammonium cations, due to their low specific surface area.