Infrared Adsorption Spectra Research Articles

Synthesis and luminescence properties of carbon quantum dots with core@shell structures

The luminescence stability of carbon quantum dots (CQDs) in air impedes their extensive applications. Ample –NH2 groups on the surface of a green carbon quantum dots (GCQDs) had high organic reactivity, the surface of GCQDs was modified with allyl functional groups through a simple surface substitution reaction (named as GCQD-A). The surface of the GCQD-A was continuously formed a thin organic shell by free radical copolymerization reaction with methyl methacrylate and styrene respectively, and they were named as GCQD@PMMA and GCQD@PS respectively. The allyl functional groups on the surface of GCQD-A, the shell composition of GCQD@PMMA and GCQD@PS were characterized by their 1H nuclear magnetic resonance (1H NMR) data and infrared adsorption spectra. The luminescence stabilities for GCQD@PMMA and GCQD@PS in air were greatly improved compared with that for the GCQDs. The work can provide a novel method to get stable luminescence of CQDs in air, and it will extend their application areas in solid state.

Recrystallization of Triple Superphosphate Produced from Oyster Shell Waste for Agronomic Performance and Environmental Issues

Calcium dihydrogen phosphate monohydrate (Ca(H2PO4)2·H2O) (a fertilizer) was successfully synthesized through a recrystallization process using prepared triple superphosphate (TSP) derived from oyster shell waste as the starting material. This bio-green, eco-friendly process to produce an important fertilizer can promote a sustainable society. The shell-waste-derived TSP was dissolved in distilled water and kept at 30, 50, and 80 °C. Non-soluble powder and TSP solution were obtained. The TSP solution fractions were then dried, and the recrystallized products (RCP30, RCP50, and RCP80) were obtained and confirmed as Ca(H2PO4)2·H2O. Conversely, the non-soluble products (NSP30, NSP50, and NSP80) were observed as calcium hydrogen phosphate dihydrate (CaHPO4·2H2O). The recrystallized yields of RCP30, RCP50, and RCP80 were found to be 51.0%, 49.6%, and 46.3%, whereas the soluble percentages were 98.72%, 99.16%, and 96.63%, respectively. RCP30 shows different morphological plate sizes, while RCP50 and RCP80 present the coagulate crystal plates. X-ray diffractograms confirmed the formation of both the NSP and RCP. The infrared adsorption spectra confirmed the vibrational characteristics of HPO42−, H2PO4−, and H2O existed in CaHPO4·2H2O and Ca(H2PO4)2·H2O. Three thermal dehydration steps of Ca(H2PO4)2·H2O (physisorbed water, polycondensation, and re-polycondensation) were observed. Ca(H2PO4)2 and CaH2P2O7 are the thermodecomposed products from the first and second steps, whereas the final product is CaP2O6.

β-Amyloid in Cerebrospinal Fluid: How to Keep It Floating (Not Sticking) by Standardization of Preanalytic Processes and Collection Tubes.

Phosphorylated tau (pTau), total tau (tTau), and β-amyloid (Aβ) are established cerebrospinal fluid (CSF) biomarkers used to help diagnose Alzheimer disease. Preanalytic workups of CSF samples lack harmonization, making interlaboratory comparison of these biomarkers challenging. The Aβ adsorbs to sample tubes, yielding underestimated concentrations, and may result in false Alzheimerdisease diagnosis. Our primary aim was to compare Aβ recovery across multiple polypropylene tubes and to test the stability of tTau, pTau, and Aβ in the best performing tube. Eight polypropylene tubes were tested using 3 CSF pools with Aβ concentrations <500, 500-1000, and >1000 ng/L. All samples were analyzed in duplicate. Tubes were cut open to assess their different infrared adsorption spectra. Freshly drawn CSF from 14 patients was distributed into 4 Sarstedt 5-mL (no. 63.504.027; Sar5CSF) tubes, left at room temperature for up to 7 days, and analyzed for pTau, tTau, and Aβ by ELISA. Two Sarstedt 5-mL tubes and a Sarstedt 10-mL (Sar10CSF) tube showed significantly higher Aβ recovery at all 3 concentrations compared with the 5 other tubes. The infrared adsorption spectra of Sar10CSF and Sar5CSF tubes were practically identical, unlike the other tubes. No significant loss of pTau, tTau, and Aβ was observed in CSF left at room temperature for up to 7 days (P > 0.05). Recovery of Aβ from Sar5CSF tubes is equivalent to Aβ recovery from Sar10CSF tubes. Levels of pTau, tTau, and Aβ were stable for at least 7 days at room temperature but not at 37 °C.

Antioxidant activity of extract from some squid species in Khanh Hoa

The antioxidant activities against DPPH free radical of crude extracts using ethyl acetate and methanol from ink sac, muscles, and bones of 5 squid species (Uroteuthis chinensis, Uroteuthis sibogae, Uroteuthis duvaucelii, Sepia esculenta, Sepioteuthis lessoniana) collected in Khanh Hoa waters were investigated. These activities ranged from 4.21% (ethyl acetate extract from ink of U. chinensis) to 54.51% (methanol extract from muscle of S. esculenta.). The functional group analysis by infrared adsorption spectrum (FTIR) in these crude extracts revealed the absorption peaks of melanin in ink, polysaccharide in bone and protein in muscle extracts. In addition, the SDS-PAGE result of some methanol extracts showed the presence of proteins with a molecular weight of 30-150 kDa.

Adsorption properties and mechanism for Fe(III) with solvent impregnated resins containing HEHEHP

Three solvent impregnated resins (SIRs) were first prepared using two types of nonreactive polystyrene-divinylbenzene polymers (HZ818 and HZ830) and one type of reactive weak basic ion exchange resin (D301) as supports and HEHEHP (2-ethylhexyl phosphonic acid mono(2-ethylhexyl) ester) as the extractant. Then the first two prepared SIRs were coated by poly-vinyl alcohol (PVA)-H3BO3 to improve their stability. The two types of coated SIRs were called HZ818-CSIR and HZ830-CSIR, and the third type of SIR was called D301-SIR. The three adsorbents were characterized by scanning electron microscopy and infrared spectrometer. The adsorption properties of iron (III) with three adsorbents were studied by batch method from sulfuric acid medium in the range of pH 0.9–1.9. The optimal pH values of all adsorbents were found at 1.5, and the saturated adsorption capacities of HZ818-CSIR, HZ830-CSIR and D301-SIR were determined as 16.7 mg·g−1, 15.9 mg·g−1 and 25.6 mg·g−1 at 298K, respectively. The adsorption isotherms were found to be fitted with Langmuir isotherms. The adsorption kinetic behaviors of HZ818-CSIR and HZ830-CSIR were fitted with pseudo-second-order kinetic model, while that of D301-SIR with Lagergren first-order kinetic model. The adsorption mechanisms of the three adsorbents were investigated with methods of saturation, equimolar series change and infrared adsorption spectra. It was found that the adsorption mechanism of Fe(III) with HZ818-CSIR and HZ830-CSIR could be deduced as cation exchange between Fe3+ and H+ from P-OH of HEHEHP accompanied with coordination between Fe(III) ion and the phosphoryl oxygen from HEHEHP. While for the D301-SIR, only a cation exchange between Fe3+ and H+ from P-OH of HEHEHP can be proposed.

Study of Optical Characteristics of H&lt;sub&gt;2&lt;/sub&gt;S Molecule Adsorption on Ag&lt;sub&gt;n&lt;/sub&gt; (&lt;i&gt;n&lt;/i&gt;=3,5) Clusters

All electronic structures and infrared adsorption spectra of AgnH2S (n=3, 5) clusters have been performed by using density functional theory. We obtain the lowest-energy structures of Ag3, Ag5, Ag3H2S and Ag5H2S clusters. The calculation results show that the lowest-energy structures of Ag3 and Ag5 clusters are planar geometries. The lowest-energy structures of Ag3H2S and Ag5H2S can be obtained by adsorbs immediately H2S on Ag3 and Ag5 clusters. The peak of infrared spectrum is 120cm-1 for Ag3 cluster, which is smaller than that of Ag5 cluster (180 cm-1). The peak of infrared spectrum is 350cm-1 for Ag3H2S cluster, which is larger than that of Ag5H2S cluster (290 cm-1). The comparison illustrates that adsorption H2S molecule make the peak of infrared spectrum shifting to shortwave.

Synthesis and Surface Activity of N-(2-Hydroxylpropyl) Perfluorooctane Amide Foaming Agent

Non-ionic fluorocarbon surfactant N-(2-hydroxypropyl) perfluorooctane amide was synthesized via the fattyacid method using perfluorooctanoic acid and isopropyl amine as precursors.The structures of products were characterized by infrared adsorption spectra(IR) and nuclear magnetic resonance spectroscopy(NMR).The bubbling potential,foam stability,salt resistance and surface tension of the samples were evaluated and compared with sodium dodecylsulfate(SDS).The results show that foam comprehensive exponent of the product is 1.6 times that of SDS.The foaminess is not obviously influenced by the concentration of inorganic ions.The surface tensions of the samples can be increased up to 9.275 mN/m.At lower concentration,the capability of reducing surface tension is better than that of SDS.The property of the products is strongly influenced by the type and quantity of hydrogen bonds,and the content of amides in the chain of the products.

Comparison of Asphalt Ultraviolet Radiation Aging with other Aging Types by Infrared Adsorption Spectrum

This study introduces the theory of asphalt aging with infrared adsorption spectrum. Qualitative and quantificational comparisons are carried out between Karamay asphalt ultraviolet radiation aging, after which asphalt turns from sol-type to gel-type and other aging types. The variance ratio of absorbance A at 1700 cm-1in infrared spectrum chart is consistent with the tendency of asphalt’s three general indexes, including penetration, ductility and softening point. The oxidation speed of ultraviolet radiation aging is 1.80~6.23 times that of thermal aging. In addition,the process of photo-oxidation, the order of carbonyl content in different asphalt samples, the influence of ultraviolet radiation on long term aging of asphalt and other useful information has been gained for better and further researches in this field.

Purification of aluminum tridecamer salt using organic solvent precipitation

Aluminum tridecamer (Al 13) salt of 70% purity can be yielded by slowly adding base to a mixed aluminum chloride solution with sodium chloride as the primary byproduct. The purity of the so-produced Al 13 solution is typically increased to >90% using sulfate precipitation and nitrate metathesis reactions (the SO 4 2−/Ba 2+ separation method). However, the presence of excess sulfate and, as demonstrated in this study, excess chloride ions can destabilize Al 13 clusters. This study applied the organic solvent precipitation technique to purify crude Al 13 salt. The solution and solid-state 27Al nuclear magnetic resonance (NMR) spectra indicate that Al 13 purity was >95%. The infrared adsorption spectra had clear Al 13 characteristic bands. The electrospray ionization mass spectrometry (ESI-MS) tests identified Al 13 7+ species. The organic solvent precipitation method purified Al 13 clusters with minimal free Cl − ions.

Aqueous foams stabilized by hexylamine-modified Laponite particles

Stable foams have been generated in low concentration aqueous dispersions of hexylamine-modified Laponite particles. The particles are of primary size 30 nm, modified with hexylamine molecules to render them partially hydrophobic or moderate flocculants. Infrared adsorption spectra and zeta potential measurements confirm the adsorption of hexylamine molecules on the Laponite particles. The foamability, drainage behavior and microstructure of wet foams were studied in terms of their dependence on the content of Laponite particles and the concentration of hexylamine. Laser-induced confocal microscopy observations confirm that stable bubbles appear to be surrounded by a thin layer of hexylamine-modified Laponite particles, which is crucial to the stability of foams. The interfacial rheology of the same systems has been also investigated by measuring the dilational viscoelasticity as a function of hexylamine concentrations. The adsorption of particles at the air–water interface has the effect of increasing dilational surface elasticity, indicating that the gel-like layer at the interface inhibits foam drainage and bubble coalescence.

Jadarite, LiNaSiB3O7(OH), a new mineral species from the Jadar Basin, Serbia

Jadarite, ideally LiNaSiB3O7(OH), is a new mineral species from the Jadar Basin, Serbia. It occurs as massive white aggregates, several metres thick, and is relatively free from inclusions and intergrowths; however, individual subhedral (tabular, elongate) to anhedral crystals rarely exceed 5–10 μm in size. It is associated with calcite, dolomite, K-feldspar, rutile, albite, ilmenite, pyrite, and fine-grained muscovite. Searlesite, analcime, chlorite, and quartz have also been identified. Jadarite is translucent (opaque in masses) with a porcellanous lustre (masses), possesses a white streak, is brittle with a platy habit and has an uneven to conchoidal fracture. VHN200 is 390 (range 343–426) kg/mm2. Mohs’ hardness is 4–5. It shows weak pink-orange fluorescence under both short- and long-wave ultraviolet radiation. An infra-red adsorption spectrum is given and shows strong, sharp peaks at 3490 and 3418 cm−1 which indicates that water is present as (OH) only. Peaks at 1409 and 1335 cm−1 indicate the presence of BO3 groups, and between 900 and 1180 cm−1 the probable presence of BO4. In transmitted light, plates and grains of jadarite show twinning in some crystallites and for λ 590 nm n α = 1.536(± 0.001) and n γ = 1.563(± 0.001). It is non-pleochroic, biaxial, and does not show parallel extinction. In plane-polarized reflected light, the mineral is dark grey with weak bireflectance, it is non-pleochroic and has abundant white internal reflections. Wet chemical analysis combined with CHN analyzer gave the following aggregate composition: Li2O 7.3, Na2O 15.0, SiO2 26.4, B2O3 47.2, H2O 4.3, total 100.2 wt.%. The empirical formula, based on 3B atoms per formula unit ( apfu ), is: Li1.08Na1.07Si0.97B3O6.99(OH)1.06. Jadarite is monoclinic ( P 21/ n ) with a 6.818(2), b 13.794(2), c 6.756(2) A, β 111.10(2)° V 592.8(2) A3 ( Z = 4), alternatively ( P 21/ c ) with a 6.756(3), b 13.794(2), c 7.680(3) A, β 124.07(3) °, V 592.9(4) A3 and Z = 4. The measured density (Berman Balance) is 2.45 g/cm3; calculated density is 2.46 g/cm3 (on the basis of the empirical formula and unit-cell parameters refined from powder data). The six strongest X-ray powder-diffraction lines [ d in A( I )( hkl )] are: 4.666 (62) (120, 021), 3.180 (82) (200), 3.152 (74) (002), 3.027 (40) (221), 2.946 (100) (131), 2.241 (74) (3 11,151), The mineral name is for the locality in Serbia where it was discovered during mineral exploration of the Jadar Basin.

Flotation separation of marmatite from pyrrhotite using DMPS as depressant

Mercapto organic compound DMPS was used as the depressant for separation of copper activated marmatite from pyrrhotite in the presence of butyl xanthate. The flotation tests of single mineral show that DMPS has strong depressing effect on pyrrhotite in the absence and presence of copper ion, but has activated effect on marmatite in the presence of copper ion. The floatability of marmatite is improved in the pH range of 2–12. The flotation test of mixture mineral shows that copper-activated marmatite can be separated efficiently from pyrrhotite using DMPS as depressant. Infrared adsorption spectra demonstrate that there are a number of function groups such as SH and SO 3 in the molecular structure of DMPS. Xanthate and DMPS compete in their adsorption on sulfide minerals.

Effects of Solvent on Powder Characteristics of Zinc Oxide and Magnesia Prepared by Flame Spray Pyrolysis

Zinc oxide (ZnO) and magnesia (MgO) powders were made by flame spray pyrolysis of zinc acetate and magnesium acetate, respectively, dissolved in methanol-water mixture. The product powders were characterized by nitrogen adsorption, infrared adsorption (IR), X-ray diffraction (XRD) and transmission electron microscopy. The effects of solvent on powder characteristics were examined by changing methanol content (X=1-0.4) in the solvent. Polyhedral aggregates of nanoparticles were formed from the precursor solution with X=1-0.6 for both ZnO and MgO syntheses, suggesting complete evaporation of the metal species and particle formation in the gas phase. Decrease of the methanol content to X=0.4 lowered the spray flame temperatures, suppressing complete evaporation, resulting in a mixture of nanoparticles and large (e.q.>100 nm) particles for both ZnO and MgO synthesis. On the other hand, the XRD and IR spectra indicated partial hydroxide formation for MgO synthesis, differed from ZnO synthesis. The reaction with water vapor in the combustion gas can be enhanced for MgO because of the larger Gibbs energy change for hydroxylation in MgO than in ZnO.

Adsorption and vibrational spectroscopy of ammonia at mordenite: ab initio study.

The adsorption of ammonia at various active centers at the outer and inner surfaces of mordenite, involving Brønsted acid (BA) sites, terminal silanol groups, and Lewis sites has been investigated using periodic ab initio density-functional theory. It is shown that ammonia forms an ammonium ion when adsorbed at strong BA sites. The calculated adsorption energies for different BA sites vary in the interval from 111.5 to 174.7 kJ/mol depending on the local environment of the adduct. The lowest adsorption energy is found for a monodentate complex in the main channel, the highest for a tetradentate configuration in the side pocket. At weak BA sites such as terminal silanol groups or a defect with a BA site in a two-membered ring ammonia is H bonded via the N atom. Additional weak H bonds are formed between H atoms of ammonia and O atoms of neighboring terminal silanol groups. The calculated adsorption energies for such adducts range between 61.7 and 70.9 kJ/mol. The interaction of ammonia with different Lewis sites is shown to range between weak (DeltaE(ads)=17.8 kJ/mol) and very strong (DeltaE(ads)=161.7 kJ/mol), the strongest Lewis site being a tricoordinated Al atom at the outer surface. Our results are in very good agreement with the distribution of desorption energies estimated from temperature-programmed desorption (TPD) and microcalorimetry experiments, the multipeaked structure of the TPD spectra is shown to arise from strong and weak Brønsted and Lewis sites. The vibrational properties of the adsorption complexes are investigated using a force-constant approach. The stretching and bending modes of NH(4) (+) adsorbed to the zeolite are strongly influenced by the local environment. The strongest redshift is calculated for the asymmetric stretching mode involving the NH group hydrogen bonded to the bridging O atom of the BA site, the shift is largest for a monodentate and smallest for a tetradentate adsorption complex. The reduced symmetry of the adsorbate also leads to a substantial splitting of the stretching and bending modes. In agreement with experiment we show that the main vibrational feature which differentiates coordinatively bonded ammonia from a hydrogen-bonded ammonium ion is the absence of bending modes above 1630 cm(-1) and in the region between 1260 and 1600 cm(-1), and a low-frequency bending band in the range from 1130 to 1260 cm(-1). The calculated distribution of vibrational frequencies agrees very well with the measured infrared adsorption spectra. From the comparison of the adsorption data and the vibrational spectra we conclude that due to the complex adsorption geometry the redshift of the asymmetric stretching is a better measure of the acidity of an active sites than the adsorption energy.

A new collector for rare earth mineral flotation

A new collector for bastnaesite flotation - modified hydroxamic acid (MOHA) has been developed through several years laboratory research. The experimental results of flotation of pure bastnaesite mineral and rare earth ores, and the application experience in flotation plants showed that MOHA is an efficient collector for bastnaesite flotation. MOHA has stronger collector ability and higher selectivity compared to the other commonly used collectors. Through the measurements of zeta-potential, adsorption and infrared adsorption spectrum and in terms of the electronegativity theory of reagent groups, the flotation mechanism has been discussed. It was concluded that the adsorption of MOHA on bastnaesite surfaces is chemical adsorption in nature through three oxygen atoms in the polar group of MOHA chelating the surface Ce(III) of bastnaesite to form a pentagon-cycle chelate: OCNOCe(III)). Additionally, the chemisorption is accompanied with the multilayer and non-homogeneous physical adsorption of the MOHA molecules. The MOHA adsorption equation at the surfaces of bastnaesite can be expressed as: Γ = 6.76×10 −2C 1 1.02 , while the adsorption rate constant k is: k = 2.64×10 5min −1mol −1m 2.

Site-specific, coupled-harmonic-oscillator model of carbon monoxide adsorbed on extended, single-crystal surfaces and on small crystals of platinum

A model describes the vibration of CO molecules adsorbed on extended crystal surfaces and small particles of platinum by treating the molecules as coupled harmonic oscillators. The frequency of vibration of single, adsorbed CO molecule and the forces coupling the vibrations of adsorbed CO molecules depend on the coordination numbers of the platinum atoms on which the CO molecules are adsorbed. The model is applied to CO adsorbed on several extended, single-crystal surfaces of platinum and to CO adsorbed on small nearly spherical particles of platinum. A calculation gives the normal modes and infrared intensities for the idealized case of a ring of molecules adsorbed in a great circle about a small particle. This idealized example helps us understand which of the collective vibration modes contribute to the infrared adsorption spectrum for systems with three-dimensional geometries (non-infinite, non-flat surfaces).

反応雰囲気におけるボールミルでの粉砕・磨砕によるセラミックス粉体の表面処理 Ｉ

The surface nature of quartz powder pulverized in a hexane solution of cetyl alcohol or octadecyltriethoxysilane by means of a ball mill was investigated. The original quartz powder showed itself to be hydrophilic since it dispersed in water as well in an immiscible mixed dispersive medium. While quartz pulverized in a hexane solution of cetyl alcohol was hydrophilic since it dispersed in water, for an immiscible mixed dispersive medium, guartz after pulverization for 8hrs. dispersed in water, but that after pulverization for 16hrs, or longer, dispersed in hexane. These pulverized quartz powders were much more hydrophobic than the original quartz powder. The quarts powder after pulverization in a hexane solution of octadecyltriethoxysilane showed that the one after pulverization for 24hrs, dispersed in water, while the one after pulverization for 32hrs., or longer floats on water. Therefore, these quartz powder were found to be hydrophobic, but for an immiscible mixed disperse medium, the ones after pulverization for 8hrs, or longer, dispersed in the hexane phase. The characteristic absorptions due to the surface group on the quartz powder after pulverization for 64hrs. were observed in the infrared adsorption spectra. The evolved vapors of the surface group were observed in their pyrolysis curves. The increase in carbon content was found to be accompanied with an increase in surface area due to pulverization. Accordingly, the quartz powder was found to be surface-treated effectively due to pulverization. The quartz powder pulverized in the hexane solution of cetyl alcohol was hydrophilic, more hydrophobic than the original quartz powder. This is due to the formation of the equilmol OH-group as that of the alcoxy-group.

トリクロロエテン洗浄による加熱しみ発生機構とその防止法

When metal surfaces are washed with an organic solvent, heat marks often appear and these are of interest since they cause swelling when the surface is electroplated. Very few have researchers, however, have investigated the formation mechanism of the heat marks. In order to obtain heat mark-free metal surfaces, therefore, the authors have studied 1) the dependence of the rate of heat mark formation on washing conditions and time; 2) the amount of organic solvent and oil on the surface, (using the gas discharge method); 3) the rate of evaporation of organic solvent against the mole fraction of oil in the organic solvent-oil system; 4) the interaction between organic solvent and oil (using the infrared adsorption spectrum method); and 5) the metal oxides and other products by organic solvent decomposition on surface (by electron spectroscopy for chemical analysis). It was found that heat marks are formed in three steps; 1) Organic solvent remains in the oil on the metal surface; 2) The oil prevents the evaporation of the organic solvent, which decomposes to form metal chloride when heated in air; and 3) The metal chloride prevents the formation of metal oxide, and becomes visible as a heat mark because it is less shiny than the metal oxide surface. The authors have succeeded in cleaning metal surfaces sufficiently using alkali or organic solvents to produce surfaces that were free of heat marks.

Mechanistic study of carbon monoxide hydrogenation over ruthenium catalysts

The mechanism of the hydrogenation of carbon monoxide to hydrocarbon products over ruthenium catalysts has been investigated. By measuring the adsorption and observing the infrared adsorption spectra of the adsorbed species during the course of the reaction, the accumulation of surface hydrocarbon species on the ruthenium catalysts was confirmed, whereas most of the surface was covered by molecularly adsorbed carbon monoxide. The reaction intermediate was examined using carbon-13. The reactivity of deposited carbon formed by the Boudouard reaction has also been studied using carbon-13. It is concluded from the behaviour of the surface species under the reaction conditions that all the hydrocarbon products are produced via dissociatively adsorbed CO with no CO insertion. The rate-determining step has been examined, leading to the conclusion that it comprises the conversion of C1 intermediates to the reaction products.

Micropore structure of coal

Abstract The adsorption of carbon dioxide at 298 K, 273 K and 253 K by the vitrains of twelve Japanese coals and five foreign coals has been studied. The Dubinin-Polanyi equation was used in order to interpret the isotherms. Equilibrium points at different temperatures fell satisfactorily on a single straight line of the Dubinin-Polanyi equation. It was shown that it is possible to estimate the differential heat of adsorption of these coals from an isotherm obtained at a single temperature if the isotherm follows the Dubinin-Polanyi equation. The heats of adsorption of carbon dioxide on coals amounted to 6–7.5 kcal/mol regardless of rank. The rate of adsorption of carbon dioxide on coals was measured at a constant pressure of 260 mmHg at 298 K. The micropore volume, the gradient of the Dubinin plot and the rate of adsorption are discussed in relation to characteristics of their infra-red adsorption spectra. It is concluded that the micropore structure of coal is closely related to the number of hydrogen atoms bound directly to carbon atoms. A possible explanation of this is suggested.