CaO nanoparticles incorporated metal organic framework (NH2-MIL-101) for Knoevenagel condensation reaction

Porous materials based on NH₂-MIL-101(Cr) MOF and their hierarchical acid-base composite with non-precious CaO was successfully prepared using a one-pot scalable hydrothermal approach. The composites were characterized by XRD, FTIR, UV–vis, ¹HNMR, TGA, N₂ adsorption–desorption isotherms, HRTEM and FESEM. The quantitative assessment of the basic sites was performed by benzoic acid titration. The results reveal that there is no remarkable structural alterations in the NH₂-MIL-101(Cr) after incorporation of CaO. Raising the CaO content boosted the strength of and content of Lewis basic sites from 0.31 to 1.34 mmol g^?1 due to the incorporation with CaO (0.04). Knoevenagel condensation reactions were performed as the probe reactions over the CaO/NH₂-MIL-101(Cr) catalysts. Both basic and acidic sites potentially boosted the reaction. Pure NH₂-MIL-101(Cr) display the catalytic conversion in the reaction (11%) which could be attributed weak basic sites on the NH₂-MIL-101(Cr) framework. However, the conversion (%) was potentially increased over NH₂-MIL-101(Cr) loaded with various content of CaO. The highest performance of (99%) conversion was achieved for (0.04) CaO/NH₂-MIL-101(Cr) catalyst. Exceptional conversion above 90% have been obtained for benzaldehyde derivatives both withdrawing and donating electron moieties. The composites can be recycled in four runs with a very small loss in performance. Furthermore, the composites produced tend to be feasible for various catalytic processes, exploring new avenues to produce of novel inorganic and organic composite materials as heterogeneous catalysts.     

Aminated metal-organic framework (NH2-MIL-101(Cr)) incorporated polyvinylidene (PVDF) hybrid membranes: Synthesis and application in efficient removal of Congo red from aqueous solution

The efficient treatment of wastewater containing organic dyes generated in diverse industrial processes has become more crucial owing to increasing environmental concerns. In this paper, we incorporated the aminated functional NH₂-MIL-101(Cr) into the porous polyvinylidene fluoride (PVDF) to fabricate the MOFs/polymer hybrid membranes, which combined the surface activity of MOFs and the membrane's filtration plus the adsorption process, and can be used in the high-efficient removal of congo red (CR) from aqueous solution. Two synthesis strategies were employed, and both of which are useful in fabricating the NH₂-MIL-101(Cr)@PVDF hybrid membranes. The NH₂-MIL-101(Cr) particles are mainly incorporated into the pores of PVDF, and thus enhance the hydrophilicity, water flux as well as porosity of the hybrid membranes. In the adsorption experiments, the influences of various conditions including the solution pH, adsorption time, adsorption isotherms, reusability, and the filtration performances were investigated systematically, and all the hybrid membranes show evidently improved adsorption performances compared to original PVDF films. The adsorption thermal and dynamics analyses indicate that the adsorption process is mainly featured in Langmuir monolayer adsorption and chemical adsorption. The hydrogen bonding at the interface of CR/NH₂-MIL-101(Cr) is responsible for the selective adsorption of CR. The excellent reusability and the dynamic adsorption performances determine the potential applications of MOF-based hybrid membranes in the membrane separation of CR from practical waste water.     

Accelerated FeIII/FeII redox cycle of Fenton reaction system using Pd/NH2-MIL-101(Cr) and hydrogen

In this paper, a novel improvement in the catalytic Fenton reaction system named MHACF-NH₂-MIL-101(Cr) was constructed based on H₂ and Pd/NH₂-MIL-101(Cr). The improved system would result in an accelerated reduction in Fe^III, and provide a continuous and fast degradation efficiency of the 10 mg L^-1 4-chlorophenol which was the model contaminant by using only trace level Fe^II. The activity of Pd/NH₂-MIL-101(Cr) decreased from 100% to about 35% gradually during the six consecutive reaction cycles of 18 h. That could be attributed to the irreversible structural damage of NH₂-MIL-101(Cr).     

Development and tailoring of amino-functionalized activated carbon based Cucumerupsi manni Naudin seed shells for the removal of nitrate ions from aqueous solution

The removal of nitrate ions with ethylenediamine (EDA)-functionalized activated carbon (AC-NH₂) was studied in this work. Activated carbon prepared from Cucumerupsi manni Naudin seed shells using ZnCl₂ (ACZ) was functionalized with EDA via a nitric acid oxidation followed by acyl chlorination and amidation process. The effect of pH, contact time, initial concentration and co-existing ions on the adsorption of nitrate ions have been investigated. The FTIR and elemental analysis revealed that amino groups were successfully grafted onto the ACZ after functionalization. The surface area and average pore of ACZ were found to be 1008.99 m²/g and 2.02 nm respectively. However, it was noticed that, after functionalization (AC-NH₂), its surface area decreases to 113.43 m²/g meanwhile, its pore diameter increases to 2.48 nm. The experimental results of adsorption showed that AC-NH₂ exhibit excellent nitrate ions uptake performance compared to ACZ which is attributed to the presence of the grafted amino groups on the ACZ. Nitrate adsorption follows pseudo-first-order kinetic model while the equilibrium adsorption data was best fitted the Freundlich isotherm suggesting that the adsorption process was predominated by physisorption. This study demonstrates that the prepared AC-NH₂ is a promising adsorbent for nitrate ions removal from aqueous media.     

Sulfonated poly(ether ether ketone)/manganese dioxide composite for the removal of low level radionuclide ions from aqueous solution

Various composite adsorbents based on sulfonated poly(ether ether ketone)/manganese dioxide were prepared for the removal of stable and radioactive ions from contaminated aqueous solution. Batch adsorption experiments revealed superior adsorption capacities of the composite using very low initial concentration of studied elements. Starting with 1000 µg L⁻¹ contaminated solution, the maximum equilibrium metal uptake capacity reached 2.0 mg g⁻¹ for Pb²⁺, 1.9 mg g⁻¹ for Cd²⁺, Cu²⁺ and Zn²⁺, and 3.7 mg g⁻¹ for Co²⁺. In addition, the distribution coefficient reached 11,600 mL g⁻¹ for ¹³⁷Cs and 70,000 mL g⁻¹ for ²¹⁰Pb.

     

U(VI) adsorption by biochar fiber–MnO2 composites

The removal of U(VI) by biochar fibers from aqueous solutions has been investigated prior and after MnO₂ surface-deposition. The removal efficiency has been studied as a function of pH, U(VI) concentration, ionic strength, temperature and contact time. The fibers morphology and surface complexes were analyzed by SEM–EDX and FTIR, respectively. Evaluation of the experimental data indicates that the composite presents extraordinary adsorption capacity (q_max = 3.8 mmol g⁻¹, 904 mg g⁻¹), which is attributed to the formation of inner-sphere surface complexes, and that the adsorption reaction is a relatively fast, endothermic and entropy-driven process.

     

Facile synthesis of polyaniline/TiO2/graphene oxide composite for high performance supercapacitors

The polyaniline/TiO₂/graphene oxide (PANI/TiO₂/GO) composite, as a novel supercapacitor material, is synthesized by in situ hydrolyzation of tetrabutyl titanate and polymerization of aniline monomer in the presence of graphene oxide. The morphology, composition and structure of the composites as-obtained are characterized by SEM, TEM, XRD and TGA. The electrochemical property and impedance of the composites are studied by cyclic voltammetry and Nyquist plot, respectively. The results show that the introduction of the GO and TiO₂ enhanced the electrode conductivity and stability, and then improved the supercapacitive behavior of PANI/TiO₂/GO composite. Significantly, the electrochemical measurement results show that the PANI/TiO₂/GO composite has a high specific capacitance (1020 F g⁻¹ at 2 mV s⁻¹, 430 F g⁻¹ at 1 A g⁻¹) and long cycle life (over 1000 times).     

Yolk–shell microspheres assembled from Preyssler‐type NaP5W30O11014− polyoxometalate and MIL‐101(Cr) metal–organic framework: A new inorganic–organic nanohybrid for fast and selective removal of cationic organic dyes from aqueous media

Novel inorganic–organic yolk–shell microspheres based on Preyssler‐type NaP₅W₃₀O₁₁₀^14? polyoxometalate and MIL‐101(Cr) metal–organic framework (P₅W₃₀/MIL‐101(Cr)) were synthesized by reaction of K_12.5Na_1.5[NaP₅W₃₀O₁₁₀], Cr(NO₃)₃·9H₂O and terephthalic acid under hydrothermal conditions at 200°C for 24 h. The as‐prepared yolk–shell microspheres were fully characterized using various techniques. All analyses confirmed the incorporation of the Preyssler‐type NaP₅W₃₀O₁₁₀^14? polyoxometalate into the three‐dimensional porous MIL‐101(Cr) metal–organic framework. The results revealed that P₅W₃₀/MIL‐101(Cr) demonstrated rapid adsorption of cationic methylene blue (MB) and rhodamine B (RhB) with ultrahigh efficiency and capacity, as well as achieving rapid and highly selective adsorption of MB from MB/MO (MO = methyl orange), MB/RhB and MB/RhB/MO mixtures. The P₅W₃₀/MIL‐101(Cr) adsorbent not only exhibited a high adsorption capacity of 212 mg g^?1, but also could quickly remove 100% of MB from a dye solution of 50 mg l^?1 within 8 min. The effects of some key parameters such as adsorbent dosage, initial dye concentration and initial pH on dye adsorption were investigated in detail. The equilibrium adsorption data were better fitted by the Langmuir isotherm. The adsorption kinetics was well modelled using a pseudo‐second‐order model. Also, the inorganic–organic hybrid yolk–shell microspheres could be easily separated from the reaction system and reused up to four times without any change in structure or adsorption ability. The stability and robustness of the adsorbent were confirmed using various techniques.     

Preparation of an Anti-Aggregation Silica/Zinc/Graphene Oxide Nanocomposite with Enhanced Adsorption Capacity

Nanomaterials play a significant role in adsorption treatment of dye wastewater, but irreversible aggregation of nanoparticles poses a significant problem. In this work, nanomesoporous zinc-doped silicate (NMSZ) was prepared by an in situ method. To prevent agglomeration, NMSZ was covalently bonded to graphene oxide (GO) sheets to form a nano-silica/zinc/graphene oxide composite (GO-NMSZ), aimed at removal of cationic dye methylene blue (MB). For comparison, undoped mesoporous silica (MS) was also synthesized and modified to obtain a silica/graphene oxide composite (GO-MS). The materials were characterized by powder XRD, SEM, FTIR spectroscopy, TEM, nitrogen sorption, and X-ray photoelectron spectroscopy (XPS). Preservation of the oxygen-containing groups of GO in the composites led to higher adsorption capacities. The best GO-NMSZ composite exhibited an enhanced adsorption capacity of 100.4 mg g⁻¹ for MB compared to those of undoped GO-MS (80.1 mg g⁻¹) and nongrafted NMSZ (55.7 mg g⁻¹). The nonselective character of GO-NMSZ is demonstrated by effective adsorption of anionic dye Congo red (127.4 mg g⁻¹) and neutral dye isatin (289.0 mg g⁻¹). The adsorption kinetics, adsorption isotherms, and a thermodynamic study suggested that MB adsorption occurs by chemisorption and is endothermic in nature.     

Estimation of radiological indices in Indian Sundarbans: a mangrove habitat

Stereoscopic porous microspheres based gellan gum (GG–Ca) were successfully prepared by sol–gel method using ethyl acetate as porogen and glutaraldehyde as crosslinker. The obtained GG–Ca microspheres were mainly of mesoporous with the average pore diameter was about 4 nm. It displayed a higher ability for uranium removal. In addition, the uranium adsorption process was endothermic and spontaneous following a pseudo-second-order and the adsorption isotherm was the best fit with the Freundlich model with maximum uranium capacity of 202.26 mg g⁻¹. The UO²⁺ adsorption mechanism is ion-exchange with Ca²⁺ based on SEM, EDX and XPS data analysis.

     

Preparation of poly(hydroxyethyl methacrylate-co-methacrylamidohistidine) beads and its design as a affinity adsorbent for Cu(II) removal from aqueous solutions

Different metal-complexing ligands carrying synthetic adsorbents have been reported in the literature for heavy metal removal. We have developed a novel and new approach to obtain high metal adsorption capacity utilizing 2-methacrylamidohistidine (MAH) as a metal-complexing ligand. MAH was synthesized by using methacrylochloride and histidine. Spherical beads with an average size of 150–200 μm were obtained by the radical suspension polymerization of MAH and 2-hydroxyethylmethacrylate (HEMA) conducted in an aqueous dispersion medium. Owing to the reasonably rough character of the bead surface, p(HEMA-co-MAH) beads had a specific surface area of 17.6 m² g⁻¹. Synthesized MAH monomer was characterized by NMR. p(HEMA-co-MAH) beads were characterized by swelling studies, FTIR and elemental analysis. These p(HEMA-co-MAH) affinity beads with a swelling ratio of 65%, and containing 1.6 mmol MAH g⁻¹ were used in the adsorption/desorption of copper(II) ions from metal solutions. Adsorption equilibria was achieved in ∼2 h. The maximum adsorption of Cu(II) ions onto pHEMA was ∼0.36 mg Cu(II) g⁻¹. The MAH incorporation significantly increased the Cu(II) adsorption capacity by chelate formation of Cu(II) ions with MAH molecules (122.7 mg Cu(II) g⁻¹), which was observed at pH 7.0. pH significantly affected the adsorption capacity of MAH incorporated beads. The observed adsorption order under non-competitive conditions was Cu(II)>Cr(III)>Hg(II)>Pb(II)>Cd(II) in molar basis. The chelating beads can be easily regenerated by 0.1 M HNO₃ with higher effectiveness. These features make p(HEMA-co-MAH) beads very good candidate for Cu(II) removal at high adsorption capacity.     

Defluoridation in aqueous solution by a composite of reduced graphene oxide decorated with cuprous oxide via sonochemical

The World Health Organization (WHO) has recommended the fluoride level in drinking water (1.5 mg/L) and defluoridation of water is an essential to remove of fluoride from contaminated water. Hence, the effective and rapid adsorbent Cuprous oxide-reduced graphene oxide (Cu₂O-RGO) composite was developed to overwhelm this concern. Sonochemical approach was adopted for the synthesis of desirable composite which was further characterized by XRD, FTIR, SEM, and EDS. The optimized composite (30 mg) shown the significant adsorption capacity of 34 mg/g of F⁻ solution (pH = 9), 70% removal of F⁻ solution from real experiment and Freundlich model was fitted than Langmuir and Temkin isotherms. The experimental results corroborate that adsorbent is the most effective for removal of fluoride from its polluted water.     

Polyethylene glycol functionalized Fe3O4@MIL-101(Cr) for the efficient removal of heavy metals from Ligusticum chuanxiong Hort

In recent years, the quality and safety issues of Chinese medicinal herbs have received great attention worldwide. Thereinto, heavy metal contamination has been one of the most serious concerns. Compared to the wide research in the analysis of heavy metals in medicinal herbs, the studies on the removal of heavy metals are relatively limited. In this study, polyethylene glycol functionalized Fe₃O₄@MIL-101(Cr) (Fe₃O₄@MIL-101(Cr)@PEG) was designed and synthesized to remove heavy metals from the decoction of Ligusticum chuanxiong Hort. The in-house fabricated Fe₃O₄@MIL-101(Cr)@PEG was characterized by a porous structure and a large specific surface area. Then, the efficiency of the material for the removal of five heavy metals was tested under optimal adsorption conditions. Meanwhile, the content of Senkyunolide A, Senkyunolide I, and Ferulic acid, the solid content, and the HPLC fingerprints similarity were used as the quality monitoring indicators of Ligusticum chuanxiong Hort decoction before and after the heavy metal removal. Results showed that the magnetic nanomaterial had excellent removal efficiency for As⁵⁺ (81.4 %), Cd²⁺ (88.19 %), and Pb²⁺ (83.79 %) and certain removal efficiency for Ni²⁺ (51.59 %) and Zn²⁺ (55.4 %) under the spiked concentration of 50 μg/mL. The content of Senkyunolide A, Senkyunolide I, and Ferulic acid were decreased by less than 8.00 % after the removal of heavy metals. Besides, the loss rate of solid content was only 0.18 %, and the fingerprints similarity was over 99.9 %. The results indicated that Fe₃O₄@MIL-101(Cr)@PEG could efficiently and selectively remove heavy metals from Ligusticum chuanxiong Hort without affecting its effective components. Due to the advantages of low-cost, simple manipulation, and good efficiency, the material can be recommended for heavy metals removal from the aqueous solutions of medicinal herbs, providing a new and promising application for the removal of exogenous contaminants in medicinal herbs.     

Platelike CoO/carbon nanofiber composite electrode with improved electrochemical performance for lithium ion batteries

Platelike CoO/carbon nanofiber (CNF) composite materials with porous structures are synthesized from the thermal decomposition and recrystallization of β-Co(OH)₂/CNF precursor without the need for a template or structure-directing agent. As negative electrode materials for lithium-ion batteries, the platelike CoO/CNF composite delivers a high reversible capacity of 700 mAh g⁻¹ for a life extending over hundreds of cycles at a constant current density of 200 mA g⁻¹. More importantly, the composite electrode shows significantly improved rate capability and electrochemical reversibility. Even at a current of 2 C, the platelike CoO/CNF composite maintain a capacity of 580 mAh g⁻¹ after 50 discharge/charge cycles. The improved cycling stability and rate capability of the CoO/CNF composite electrodes may be attributed to synergistic effect of the porous structural stability and improved conductivity through CNF connection.     

Fabrication of a Hierarchical Ni(OH)2@Ni3S2/Ni Foam Electrode from a Prussian Blue Analogue-Based Composite with Enhanced Electrochemical Capacitive and Electrocatalytic Properties

Developing high-efficiency, cost-effective, and durable electrodes is significant for electrochemical capacitors and electrocatalysis. Herein, a 3D bifunctional electrode consisting of nickel hydroxide nanosheets@nickel sulfide nanocubes arrays on Ni foam (Ni(OH)₂@Ni₃S₂/NF) obtained from a Prussian blue analogue-based precursor is reported. The 3D higher-order porous structure and synergistic effect of different compositions endow the electrode with large specific surface area, facile ion/electron transport path, and improved conductivity. As a result, the Ni(OH)₂@Ni₃S₂/NF electrode exhibits a high specific capacity of 211 mA h g⁻¹ at a current density of 1 A g⁻¹ and 73 % capacity retention after 5000 cycles at 5 A g⁻¹. Moreover, the Ni(OH)₂@Ni₃S₂/NF electrode has superior electrocatalytic activity for the hydrogen evolution reaction with low overpotentials of 140 and 210 mV at current densities of 10 and 100 mA cm⁻², respectively. The synthetic strategy for the unique higher-order porous structure can be extended to fabricate other composite materials for energy storage and conversion.     

The MOF+ Technique: A Significant Synergic Effect Enables High Performance Chromate Removal

A significant synergic effect between a metal–organic framework (MOF) and Fe₂SO₄, the so‐called MOF⁺ technique, is exploited for the first time to remove toxic chromate from aqueous solutions. The results show that relative to the pristine MOF samples (no detectable chromate removal), the MOF⁺ method enables super performance, giving a 796 Cr mg g⁻¹ adsorption capacity. The value is almost eight‐fold higher than the best value of established MOF adsorbents, and the highest value of all reported porous adsorbents for such use. The adsorption mechanism, unlike the anion‐exchange process that dominates chromate removal in all other MOF adsorbents, as unveiled by X‐ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM), and transmission electron microscopy (TEM), is due to the surface formation of Fe_0.75Cr_0.25(OH)₃ nanospheres on the MOF samples.     

Determination of Cr(VI) in plants by electrothermal atomic absorption spectrometry after leaching with sodium carbonate

The determination of chromium (VI) compounds in plants by electrothermal atomic absorption spectrometry (ET AAS) is proposed based on their leaching with 0.1 M Na₂CO₃. Due to the presence of relatively high amounts of Na₂CO₃ in the resulting samples, the temperature and time of pyrolysis and atomization stages must be optimized to minimize the influence of the matrix. A limit of detection (LOD) for determination of Cr(VI) in plants by ET AAS was found to be 0.024 μg g⁻¹.The concentration of Cr(VI) and total chromium in plants collected in different geographical areas (South Africa and Russia), grown on soils high in chromium was determined. The concentration of Cr(VI) and total Cr in stems and leaves of plants was in the range of 0.04–0.7 μg g⁻¹ and 0.5–10 μg g⁻¹, respectively. The limited uptake of Cr(III) by plants, in comparison to its concentration in soil, can be explained by the very low solubility of natural Cr(III) compounds.Results for the determination of Cr(VI) were confirmed by the analysis of BCR CRM 545 (Cr(VI) in welding dust) with good agreement between certified (39.5 ± 1.3 μg mg⁻¹) and found (38.8 ± 1.2 μg mg⁻¹) values. The total concentration of Cr in plants has also been determined by ET AAS after dry ashing of samples at 650 °C. Results were confirmed by the analysis of BCR CRM 281 (Trace elements in Rye Grass) with good agreement between the found (2.12 ± 0.16 μg g⁻¹) and certified value (2.14 ± 0.12 μg g⁻¹).     

Fabrication of zirconium(IV) cross-linked alginate/kaolin hybrid beads for nitrate and phosphate retention

The extreme nitrate (NO₃⁻) species in drinking water leads to methemoglobinemia (blue baby syndrome) disease in new born toddlers whereas the excess phosphate (PO₄³⁻) and NO₃⁻ contents lead to the eutrophication (algae growth) problem of water sources. Upto date, the environmental researchers have developing the suitable adsorbent materials for providing NO₃⁻ and PO₄³⁻ free water system. In present study, a low-cost alginate (Alg) assisted kaolin (KN) (AlgKN) composite beads were prepared and utilized for the removal of NO₃⁻ and PO₄³⁻. To improve the sorption capacity (SC) and stability, Zr⁴⁺ ions were coated onto AlgKN to get Zr@AlgKN composite beads which were prepared via., hydrothermal (Hydro) and in situ precipitation (In situ) methods. The hydro assisted Zr@AlgKN composite beads possess an enhanced SC than the in situ assisted adsorbents. In batch scale, the parameters responsible for the adsorption process such as contact time, co-ions, adsorbent dosage, pH, initial ions concentration and temperature were optimized. The adsorbents were characterized by XRD, FTIR, BET, EDAX and SEM analysis. The adsorption experimental data was fitted with isotherms, kinetics and thermodynamic parameters. The regeneration and field applicability study of the Zr@AlgKN composite beads were also investigated.     

Sulfur-/Nitrogen-Rich Albumen Derived “Self-Doping” Graphene for Sodium-Ion Storage

The development of sodium-ion batteries (SIBs) is hindered by the rapid reduction in reversible capacity of carbon-based anode materials. Outside-in doping of carbon-based anodes has been extensively explored. Nickel and NiS₂ particles embedded in nitrogen and sulfur codoped porous graphene can significantly improve the electrochemical performance. Herein a built-in heteroatom “self-doping” of albumen-derived graphene for sodium storage is reported. The built-in sulfur and nitrogen in albumen act as the doping source during the carbonization of proteins. The sulfur-rich proteins in albumen can also guide the doping and nucleation of nickel sulfide nanoparticles. Additionally, the porous architecture of the carbonized proteins is achieved through removable KCl/NaCl salts (medium) under high-temperature melting conditions. During the carbonization process, nitrogen can also reduce the carbonization temperature of thermally stable carbon materials. In this work, the NS-graphene delivered a specific capacity of 108.3 mAh g⁻¹ after 800 cycles under a constant current density of 500 mA g⁻¹. In contrast, the Ni/NiS₂/NS-graphene maintained a specific capacity of 134.4 mAh g⁻¹; thus the presence of Ni/NiS₂ particles improved the electrochemical performance of the whole composite.     

Synthesis of nitrogen doped activated carbon/polyaniline material for CO2 adsorption

The equilibrium adsorption isotherms of carbon dioxide and nitrogen on the nitrogen doped activated carbon (NAC) prepared by the chemical activation of a pine cone‐based char/polyaniline composite were measured using a volumetric technique. CO₂ and N₂ adsorption experiments were done at three different temperatures (298, 308, and 318 K) and pressures up to 16 bar, and correlated with the Langmuir, Freundlich, and Sips models. The Sips isotherm model presented the best fit to the experimental data. The N‐doped adsorbent showed CO₂ and N₂ adsorption capacity of 3.96 mmol·g⁻¹ and 0.86 mmol·g⁻¹, respectively, at 298 K and 1 bar. The selectivity predicted by ideal adsorbed solution theory (IAST) model was achieved 47.17 for NAC at 1 bar and y_N2 = 0.85 which is a composition similar to flue gas. The results showed that NAC adsorbent has a high CO₂‐over‐N₂ selectivity in a binary mixture. The relatively fast sorption rate of CO₂ on NAC compared to N₂ indicates the stronger affinity between CO₂ and amine groups. The isosteric heat of adsorption of CO₂ by the NAC demonstrated the physico‐chemical adsorption of CO₂ on the adsorbent surface. These data showed that prepared NAC could be successfully applied in separation of CO₂ from N₂.