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1.
Barbara Bonelli Dr. Carlos Otero Areán Prof. Marco Armandi Dr. Montserrat Rodríguez Delgado Dr. Edoardo Garrone Prof. 《Chemphyschem》2008,9(12):1747-1751
Variable temperature FT–IR spectroscopy (in the range of 298–380 K) is used to study the thermodynamics of formation of Ca2+???CO carbonyl species upon CO adsorption on the faujasite‐type zeolite Ca–Y, and also the (temperature‐dependent) isomerization equilibrium between carbonyl and isocarbonyl (Ca2+???OC) species. The standard enthalpy and entropy changes involved in formation of the monocarbonyl species resulted to be ΔH0=?50.3 (±0.5) kJ mol?1 and ΔS0=?186 (±5) J mol?1 K?1, respectively. Isomerization of the (C‐bonded) Ca2+???CO carbonyl to yield the (O‐bonded) Ca2+???OC isocarbonyl involves an enthalpy change =+11.4 (±1.0) kJ mol?1. These results are compared with previously reported data for the CO/Sr–Y system; and also, a brief analysis of enthalpy–entropy correlation for CO adsorption on zeolites and metal oxides is given. 相似文献
2.
Marco Armandi Dr. Edoardo Garrone Prof. Carlos O. Areán Prof. Barbara Bonelli Dr. 《Chemphyschem》2009,10(18):3316-3319
Adsorption of carbon dioxide on H‐ZSM‐5 zeolite (Si:Al=11.5:1) was studied by means of variable‐temperature FT‐IR spectroscopy, in the temperature range of 310–365 K. The adsorbed CO2 molecules interact with the zeolite Brønsted‐acid OH groups bringing about a characteristic red‐shift of the O? H stretching band from 3610 cm?1 to 3480 cm?1. Simultaneously, the ν3 mode of adsorbed CO2 is observed at 2345 cm?1. From the variation of integrated intensity of the IR absorption bands at both 3610 and 2345 cm?1, upon changing temperature (and CO2 equilibrium pressure), the standard adsorption enthalpy of CO2 on H‐ZSM‐5 is ΔH0=?31.2(±1) kJ mol?1 and the corresponding entropy change is ΔS0=?140(±10) J mol?1 K?1. These results are discussed in the context of available data for carbon dioxide adsorption on other protonic, and also alkali‐metal exchanged, zeolites. 相似文献
3.
The dynamic behavior of the N,N,N′,N′‐tetramethylethylenediamine (tmeda) ligand has been studied in solid lithium‐fluorenide(tmeda) ( 3 ) and lithium‐benzo[b]fluorenide(tmeda) ( 4 ) using CP/MAS solid‐state 13C‐ and 15N‐NMR spectroscopy. It is shown that, in the ground state, the tmeda ligand is oriented parallel to the long molecular axis of the fluorenide and benzo[b]fluorenide systems. At low temperature (<250 K), the 13C‐NMR spectrum exhibits two MeN signals. A dynamic process, assigned to a 180° rotation of the five‐membered metallacycle (π‐flip), leads at elevated temperatures to coalescence of these signals. Line‐shape calculations yield ΔH?=42.7 kJ mol?1, ΔS?=?5.3 J mol?1 K?1, and =44.3 kJ mol?1 for 3 , and ΔH?=36.8 kJ mol?1, ΔS?=?17.7 J mol?1 K?1, and =42.1 kJ mol?1 for 4 , respectively. A second dynamic process, assigned to ring inversion of the tmeda ligand, was detected from the temperature dependence of T1ρ, the 13C spin‐lattice relaxation time in the rotating frame, and led to ΔH?=24.8 kJ mol?1, ΔS?=?49.2 J mol?1 K?1, and =39.5 kJ mol?1 for 3 , and ΔH?=18.2 kJ mol?1, ΔS?=?65.3 J mol?1 K?1, and =37.7 kJ mol?1 for 4 , respectively. For (D12)‐ 3 , the rotation of the CD3 groups has also been studied, and a barrier Ea of 14.1 kJ mol?1 was found. 相似文献
4.
Hua Y Ramabhadran RO Uduehi EO Karty JA Raghavachari K Flood AH 《Chemistry (Weinheim an der Bergstrasse, Germany)》2011,17(1):312-321
Triazolophanes are used as the venue to compete an aliphatic propylene CH hydrogen‐bond donor against an aromatic phenylene one. Longer aliphatic C? H ??? Cl? hydrogen bonds were calculated from the location of the chloride within the propylene‐based triazolophane. The gas‐phase energetics of chloride binding (ΔGbind, ΔHbind, ΔSbind) and the configurational entropy (ΔSconfig) were computed by taking all low‐energy conformations into account. Comparison between the phenylene‐ and propylene‐based triazolophanes shows the computed gas‐phase free energy of binding decreased from ΔGbind=?194 to ?182 kJ mol?1, respectively, with a modest enthalpy–entropy compensation. These differences were investigated experimentally. An 1H NMR spectroscopy study on the structure of the propylene triazolophane’s 1:1 chloride complex is consistent with a weaker propylene CH hydrogen bond. To quantify the affinity differences between the two triazolophanes in dichloromethane, it was critical to obtain an accurate binding model. Four equilibria were identified. In addition to 1:1 complexation and 2:1 sandwich formation, ion pairing of the tetrabutylammonium chloride salt (TBA+ ? Cl?) and cation pairing of TBA+ with the 1:1 triazolophane–chloride complex were observed and quantified. Each complex was independently verified by ESI‐MS or diffusion NMR spectroscopy. With ion pairing deconvoluted from the chloride–receptor binding, equilibrium constants were determined by using 1H NMR (500 μM ) and UV/Vis (50 μM ) spectroscopy titrations. The stabilities of the 1:1 complexes for the phenylene and propylene triazolophanes did not differ within experimental error, ΔG=(?38±2) and (?39±1) kJ mol?1, respectively, as verified by an NMR spectroscopy competition experiment. Thus, the aliphatic CH donor only revealed its weaker character when competing with aromatic CH donors within the propylene‐based triazolophane. 相似文献
5.
6.
Density Functional Theory Study of Hydrogen Adsorption in a Ti‐Decorated Mg‐Based Metal–Organic Framework‐74
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Pitphichaya Suksaengrat Prof. Dr. Vittaya Amornkitbamrung Dr. Pornjuk Srepusharawoot Prof. Dr. Rajeev Ahuja 《Chemphyschem》2016,17(6):879-884
The Ti‐binding energy and hydrogen adsorption energy of a Ti‐decorated Mg‐based metal–organic framework‐74 (Mg‐MOF‐74) were evaluated by using first‐principles calculations. Our results revealed that only three Ti adsorption sites were found to be stable. The adsorption site near the metal oxide unit is the most stable. To investigate the hydrogen‐adsorption properties of Ti‐functionalized Mg‐MOF‐74, the hydrogen‐binding energy was determined. For the most stable Ti adsorption site, we found that the hydrogen adsorption energy ranged from 0.26 to 0.48 eV H2?1. This is within the desirable range for practical hydrogen‐storage applications. Moreover, the hydrogen capacity was determined by using ab initio molecular dynamics simulations. Our results revealed that the hydrogen uptake by Ti‐decorated Mg‐MOF‐74 at temperatures of 77, 150, and 298 K and ambient pressure were 1.81, 1.74, and 1.29 H2 wt %, respectively. 相似文献
7.
Dr. Masaru Kubo Hayato Hagi Prof. Dr. Atsushi Shimojima Prof. Dr. Tatsuya Okubo 《化学:亚洲杂志》2013,8(11):2801-2806
A facile synthesis of partially hydroxy‐modified MOF‐5 and its improved H2‐adsorption capacity by lithium doping are reported. The reaction of Zn(NO3)2 ? 6 H2O with a mixture of terephthalic acid (H2BDC) and 2‐hydroxyterephthalic acid (H2BDC‐OH) in DMF gave hydroxy‐modified MOF‐5 (MOF‐5‐OH‐x), in which the molar fraction (x) of BDC‐OH2? was up to 0.54 of the whole ligand. The MOF‐5‐OH‐x frameworks had high BET surface areas (about 3300 m2 g?1), which were comparable to that of MOF‐5. We suggest that the MOF‐5‐OH‐x frameworks are formed by the secondary growth of BDC2?‐rich MOF‐5 seed crystals, which are nucleated during the early stage of the reaction. Subsequent Li doping into MOF‐5‐OH‐x results in increased H2 uptake at 77 K and 0.1 MPa from 1.23 to 1.39 wt. % and an increased isosteric heat of H2 adsorption from 5.1–4.2 kJ mol?1 to 5.5–4.4 kJ mol?1. 相似文献
8.
The recognition of 4‐alkylpyridines by water‐soluble poly(ethylene oxide)–zinc porphyrin conjugates was studied with a focus on the thermodynamic parameters of binding. Microcalorimetric studies indicated that binding of the alkyl group of the guest in water is driven by the entropic term (δΔH0=ΔH0(4‐pentylpyridine)? ΔH0(4‐methylpyridine)=+1.7 kJ mol?1, δTΔS0=TΔS0(4‐pentylpyridine)? TΔS0(4‐methylpyridine)=+11.8 kJ mol?1 at 298 K), thus showing the significance of water reorganization during host–guest interaction. The enthalpy–entropy compensation temperature of binding of 4‐alkylpyridines was as low as 38 K; only below this temperature could the enthalpic term be a driving force. The binding affinity was modulated by the addition of cations and by varying the degree of polymerization of poly(ethylene oxide), which suggests that guest binding is coupled with polymer conformation. 相似文献
9.
Ondrej Kysel Šimon Budzák Miroslav Medveď Pavel Mach 《International journal of quantum chemistry》2008,108(9):1533-1545
Geometry, thermodynamic, and electric properties of the π‐EDA complex between hexamethylbenzene (HMB) and tetracyanoethylene (TCNE) are investigated at the MP2/6‐31G* and, partly, DFT‐D/6‐31G* levels. Solvent effects on the properties are evaluated using the PCM model. Fully optimized HMB–TCNE geometry in gas phase is a stacking complex with an interplanar distance 2.87 × 10?10 m and the corresponding BSSE corrected interaction energy is ?51.3 kJ mol?1. As expected, the interplanar distance is much shorter in comparison with HF and DFT results. However the crystal structures of both (HMB)2–TCNE and HMB–TCNE complexes have interplanar distances somewhat larger (3.18 and 3.28 × 10?10 m, respectively) than our MP2 gas phase value. Our estimate of the distance in CCl4 on the basis of PCM solvent effect study is also larger (3.06–3.16 × 10?10 m). The calculated enthalpy, entropy, Gibbs energy, and equilibrium constant of HMB–TCNE complex formation in gas phase are: ΔH0 = ?61.59 kJ mol?1, ΔS = ?143 J mol?1 K?1, ΔG0 = ?18.97 kJ mol?1, and K = 2,100 dm3 mol?1. Experimental data, however, measured in CCl4 are significantly lower: ΔH0 = ?34 kJ mol?1, ΔS = ?70.4 J mol?1 K?1, ΔG0 = ?13.01 kJ mol?1, and K = 190 dm3 mol?1. The differences are caused by solvation effects which stabilize more the isolated components than the complex. The total solvent destabilization of Gibbs energy of the complex relatively to that of components is equal to 5.9 kJ mol?1 which is very close to our PCM value 6.5 kJ mol?1. MP2/6‐31G* dipole moment and polarizabilities are in reasonable agreement with experiment (3.56 D versus 2.8 D for dipole moment). The difference here is due to solvent effect which enlarges interplanar distance and thus decreases dipole moment value. The MP2/6‐31G* study supplemented by DFT‐D parameterization for enthalpy calculation, and by the PCM approach to include solvent effect seems to be proper tools to elucidate the properties of π‐EDA complexes. © 2008 Wiley Periodicals, Inc. Int J Quantum Chem, 2008 相似文献
10.
Pantelis Charisiadis Constantinos G. Tsiafoulis Andreas G. Tzakos Ioannis P. Gerothanassis 《Magnetic resonance in chemistry : MRC》2014,52(12):764-768
The direct in situ NMR observation and quantification, based on the aldehyde –CH chemical shift region, of the inter‐conversion of secoiridoid derivatives due to temperature and solvent effects is demonstrated in complex extracts of natural products without prior isolation of the individual components. The equilibrium between the aldehyde hydrate form and the dialdehyde form of the oleuropein aglycon of an olive leaf aqueous extract in D2O was shown to be temperature dependent. The resulting thermodynamic values of the Van't Hoff plot with ΔHo = ?26.34 ± 1.00 kJ mol?1 and TΔS° (298 K) = ?24.70 ± 1.00 kJ mol?1 demonstrate a significant entropy term which nearly compensates the effect of enthalpy at room temperature. The equilibrium between the two diastereomeric hemiacetal forms and the dialdehyde form of the oleuropein 6‐O‐β‐d ‐glucopyranoside aglycon of an olive leaf aqueous extract in CD3OD was also shown to be strongly temperature dependent again because of the significant entropy term (TΔS° (298 K) = ?26.50 ± 1.39 kJ mol?1) compared with that of the enthalpy term (ΔHo = ?36.64 ± 1.46 kJ mol?1). This is the first demonstration of the significant role of the entropy parameter in determining the equilibrium of chemical transformations in complex mixtures of natural products due to solvent and temperature effects. Copyright © 2014 John Wiley & Sons, Ltd. 相似文献
11.
A Remarkable Solvent Effect on the Nuclearity of Neutral Titanium(IV)‐Based Helicate Assemblies
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David Michael Weekes Carine Diebold Dr. Pierre Mobian Dr. Clarisse Huguenard Dr. Lionel Allouche Prof. Marc Henry 《Chemistry (Weinheim an der Bergstrasse, Germany)》2014,20(17):5092-5101
The spontaneous self‐assembly of a neutral circular trinuclear TiIV‐based helicate is described through the reaction of titanium(IV) isopropoxide with a rationally designed tetraphenolic ligand. The trimeric ring helicate was obtained after diffusion of n‐pentane into a solution with dichloromethane. The circular helicate has been characterized by using single‐crystal X‐ray diffraction study, 13C CP‐MAS NMR and 1H NMR DOSY solution spectroscopic, and positive electrospray ionization mass‐spectrometric analysis. These analytical data were compared with those obtained from a previously reported double‐stranded helicate that crystallizes in toluene. The trimeric ring was unstable in a pure solution with dichloromethane and transformed into the double‐stranded helicate. Thermodynamic analysis by means of the PACHA software revealed that formation of the double‐stranded helicates was characterized by ΔH(toluene)=?30 kJ mol?1 and ΔS(toluene)=+357 J K?1 mol?1, whereas these values were ΔH(CH2Cl2)=?75 kJ mol?1 and ΔS(CH2Cl2)=?37 J K?1 mol?1 for the ring helicate. The transformation of the ring helicate into the double‐stranded helicate was a strongly endothermic process characterized by ΔH(CH2Cl2)=+127 kJ mol?1 and ΔH(n‐pentane)=+644 kJ mol?1 associated with a large positive entropy change ΔS=+1115 J K?1?mol?1. Consequently, the instability of the ring helicate in pure dichloromethane was attributed to the rather high dielectric constant and dipole moment of dichloromethane relative to n‐pentane. Suggestions for increasing the stability of the ring helicate are given. 相似文献
12.
Hüseyin Karaca Devrim Türker Murat Teker 《Journal of Dispersion Science and Technology》2013,34(12):1800-1807
AbstractIn this study the effect of the dose and particle size of the adsorbent, initial dye concentration, initial pH, contact time and temperature were investigated for the removal of by means of fly ash (FA) methylene blue (MB) from an aqueous solution. The FA dose was found to be 2.0?g and the under 270 mesh sized particles were found to be effective particles for adsorption. The adsorption process reached its maximum value at 0.5?mg/L dye concentration and attained equilibrium within 10?minutes. The adsorption isotherm was found to follow the Langmuir model. The estimated adsorption free energy (ΔGo), enthalpy change (ΔHo), and entropy change (ΔSo) for the adsorption process were ?37.77?kJ mol?1, ?13.44?kJ mol?1 and 122 J mol?1 K?1 respectively at 298 K. The maximum adsorption capacity is 0,12?mg g?1 at 298 K and 0,07?mg g?1 at 398 K. The adsorption process was exothermic, feasible and spontaneous. The positive value of ΔSo shows the affinity of FA for MB while the low value of ΔGo suggests a physical adsorption process. 相似文献
13.
A new preconcentration method is presented for lead on TAN‐loaded polyurethane foam (PUF) and its measurement by differential pulse anodic stripping voltammetry (DPASV). The optimum sorption conditions of 1.29 × 10?5 M solution of Pb(II) ions on TAN‐loaded PUF were investigated. The maximum sorption was observed at pH 7 with 20 minutes equilibrated time on 7.25 mg mL?1 of TAN‐loaded foam. The kinetic study indicates that the overall sorption process was controlled by the intra‐particle diffusion process. The validity of Freundlich, Langmuir and Dubinin ‐ Radushkevich adsorption isotherms were tested. The Freundlich constants 1/n and KF are evaluated to be 0.45 ±0.04 and (1.03 +0.61) × 10?3 mol g?1, respectively. The monolayer sorption capacity and adsorption constant related to the Langmuir isotherm are (1.38 ± 0.08) × 10?5 mol g?1 and (1.46 ± 0.27) × 105 L mol?1, respectively. The mean free energy of Pb(II) ions sorption on‐TAN loaded PUF is 11.04 ± 0.28 kJ mol?1 indicating chemisorption phenomena. The effect of temperature on the sorption yields thermodynamics parameters of ΔH, ΔS and ΔG at 298 K that are 15.0 ± 1.4 kJ mol?1, 74 ±5 J mol?1 K?1 and ‐7.37 ± 0.28 kJ mol?1, respectively. The positive values of enthalpy (ΔH) and entropy (ΔS) indicate the endothermic sorption and stability of the sorbed complexes are entropy driven. However, the negative value of Gibb's free energy (ΔG) indicates the spontaneous nature of sorption. On the basis of these data, the sorption mechanism has been postulated. The effect of different foreign ions on the sorption and desorption studies were also carried out. The method was successfully applied for the determination of lead from different water samples at ng levels. 相似文献
14.
用精密自动绝热量热计测定了4-硝基苯甲醇(4-NBA)在78 ~ 396 K温区的摩尔热容。其熔化温度、摩尔熔化焓及摩尔熔化熵分别为:(336.426 ± 0.088) K, (20.97 ± 0.13) kJ×mol-1 和 (57.24 ± 0.36) J×K-1×mol-1.根据热力学函数关系式,从热容值计算出了该物质在80 ~ 400 K温区的热力学函数值 [HT - H298.15 K] 和[ST - S298.15 K]. 用精密氧弹燃烧量热计测定了该物质在T=298.15 K的恒容燃烧能和标准摩尔燃烧焓分别为 (C7H7NO3, s)=- ( 3549.11 ± 1.47 ) kJ×mol-1 和 (C7H7NO3, s)=- ( 3548.49 ± 1.47 ) kJ×mol-1. 利用标准摩尔燃烧焓和其他辅助热力学数据通过盖斯热化学循环, 计算出了该物质标准摩尔生成焓 (C7H7NO3, s)=- (206.49 ± 2.52) kJ×mol-1 . 相似文献
15.
Hydrogen Storage in a Potassium‐Ion‐Bound Metal–Organic Framework Incorporating Crown Ether Struts as Specific Cation Binding Sites
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Dr. Dae‐Woon Lim Seung An Chyun Prof. Myunghyun Paik Suh 《Angewandte Chemie (International ed. in English)》2014,53(30):7819-7822
To develop a metal–organic framework (MOF) for hydrogen storage, SNU‐200 incorporating a 18‐crown‐6 ether moiety as a specific binding site for selected cations has been synthesized. SNU‐200 binds K+, NH4+, and methyl viologen(MV2+) through single‐crystal to single‐crystal transformations. It exhibits characteristic gas‐sorption properties depending on the bound cation. SNU‐200 activated with supercritical CO2 shows a higher isosteric heat (Qst) of H2 adsorption (7.70 kJ mol?1) than other zinc‐based MOFs. Among the cation inclusions, K+ is the best for enhancing the isosteric heat of the H2 adsorption (9.92 kJ mol?1) as a result of the accessible open metal sites on the K+ ion. 相似文献
16.
In this work, we determined the stability parameters of bovine β-lactoglobulin, variant A, (BLG-A), in relation to their transition curves induced by cetylpyridinium chloride (CPC) as a cationic surfactant. The experiments took place over the temperature range of 298 K to 358 K. For each transition curve at any specific temperature, the conventional method of analysis, which assumes a linear concentration dependence of the pre- and post-transition base lines, gave the most realistic values for ΔGD(H2O). Results show that the minimum value of ΔGD(H2O) occurs at T = 328 K. Using the Gibbs–Helmholtz equation, the values of enthalpy, ΔHD, and entropy, ΔSD, of denaturation have been calculated considering temperature dependence of ΔGD at any specified concentration of CPC. The values of 12.05 kJ · mol−1, 18.54 kJ · mol−1, and 18.32 J · mol−1 · K−1, were obtained for ΔGD(H2O), ΔHD(H2O), and ΔSD(H2O), respectively. The results show that the enthalpy term dominates the entropy term. 相似文献
17.
Thermochemical Properties and Non-isothermal Decomposition Reaction Kinetics of N-Guanylurea Dinitramide (GUDN) 总被引:4,自引:0,他引:4
Introduction N-Guanylurea dinitramide (GUDN) is a new ener-getic oxidizer with higher energy and lower sensitivity. Its crystal density is 1.755 g·cm-3. The detonation velocity is about 8210 m·s-1. Its specific impulse and pressure exponent are 213.1 s and 0.73, respectively. It has the potential for possible use as an energy ingredient of propellants and explosives from the point of view of the above-mentioned high performance. Its preparation,1 properties2 and hygroscopocity2 have been … 相似文献
18.
在干燥氩气氛下, 用等摩尔的高纯无水GaCl3和[C2mim][Cl](氯化1-甲基-3-乙基咪唑)直接搅拌混合, 制备了淡黄色透明的的离子液体[C2mim][GaCl4] (1-ethyl-3-methylimidazolium chlorogallate) . 在298.15 K下, 利用具有恒温环境的溶解反应热量计, 测定了这种离子液体的不同浓度摩尔溶解焓 . 针对[C2mim][GaCl4]溶解于水后即分解的特点, 在Pitzer电解质溶液理论基础上, 提出了确定这种离子液体标准摩尔溶解焓的新方法, 得到了[C2mim][GaCl4]在水中的标准摩尔溶解焓, =-132 kJ•mol-1, 以及Pitzer焓参数组合: =-0.1373076和 =0.3484209. 借助热力学循环和Glasser离子液体晶格能理论, 用Ga3+, Cl-和[C2mim]—的离子水化焓数据以及本文得到的[C2mim][GaCl4]标准摩尔溶解焓, 估算了配离子4Cl-(g)解离成Ga3+(g)和4Cl-(g)的解离焓ΔHdis([GaCl4]-)≈5855 kJ•mol-1. 这个结果揭示了离子液体[C2mim][GaCl4]的标准摩尔溶解焓绝对值并不很大的原因, 即是很大的离子水化焓被很大的[GaCl4]-(g)的解离焓相互抵消了. 相似文献
19.
Teng Liu Peng Li Na Yao Gongzhen Cheng Shengli Chen Wei Luo Yadong Yin 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2019,131(14):4727-4732
Although electrocatalysts based on transition metal phosphides (TMPs) with cationic/anionic doping have been widely studied for hydrogen evolution reaction (HER), the origin of performance enhancement still remains elusive mainly due to the random dispersion of dopants. Herein, we report a controllable partial phosphorization strategy to generate CoP species within the Co‐based metal‐organic framework (Co‐MOF). Density functional theory calculations and experimental results reveal that the electron transfer from CoP to Co‐MOF through N‐P/N‐Co bonds could lead to the optimized adsorption energy of H2O (ΔG ) and hydrogen (ΔGH*), which, together with the unique porous structure of Co‐MOF, contributes to the remarkable HER performance with an overpotential of 49 mV at a current density of 10 mA cm?2 in 1 m phosphate buffer solution (PBS, pH 7.0). The excellent catalytic performance exceeds almost all the documented TMP‐based and non‐noble‐metal‐based electrocatalysts. In addition, the CoP/Co‐MOF hybrid also displays Pt‐like performance in 0.5 m H2SO4 and 1 m KOH, with the overpotentials of 27 and 34 mV, respectively, at a current density of 10 mA cm?2. 相似文献
20.
Adsorption of Metanil Yellow Azoic Dye from Aqueous Solution onto Mg‐Fe‐NO3 Layered Double Hydroxide
Dr. Kamellia Nejati Zolfaghar Rezvani Mahsa Mansurfar Abolfazl Mirzaee Mehrdad Mahkam 《无机化学与普通化学杂志》2011,637(11):1573-1579
We report the preparation and characterization of a layered double hydroxide (LDH) adsorbent for azoic dye, metanil yellow (yellow GX; YGX) removal. The nanoparticles of Mg‐Fe‐LDH‐NO3 adsorbent were prepared with Mg/Fe molar ratio of 3:1 by a hydrothermal process and coprecipitation method at pH 9.5 and were characterized by X‐ray powder diffraction (XRPD), thermal gravimetric analysis (TGA), elemental analysis, and Fourier transform infrared spectroscopy (FT‐IR). The size and morphology of nanoparticles were examined by scanning electron microscopy (SEM). The XRD patterns indicate that the intercalation of YGX between the LDH layers has not occurred and surface adsorption has happened. In the adsorption experiments, the Gibbs free energy ΔG0 values, the enthalpy ΔH0, and entropy ΔS0 was determined. The isotherms showed that the adsorption of YGX by Mg‐Fe‐LDH‐NO3 was both consistent with Langmuir and Freundlich equations. 相似文献