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91.
Heider Nasser ákos Rédey Tatiana Yuzhakova Zsolt Németh Tóth Tamás Ollár 《Reaction Kinetics and Catalysis Letters》2007,92(2):329-335
CO adsorption at low temperature has been used to probe Lewis acid sites created upon dehydroxylation of γ-Al2O3 and reduction of Mo/Al2O3 catalysts, using Fourier Transform Infrared spectroscopy (FTIR).
Carbon-monoxide adsorption on γ-Al2O3 and Mo/Al2O3 catalysts dehydroxylated and reduced at different temperatures was studied at 78 K by IR spectroscopy. However, our results
indicate that there is an approximately linear correlation between the increase either of dehydroxylation or the extent of
reduction of the catalysts and the increasing absorbance of CO due to CO adsorption on Lewis acid sites created upon dehydroxylation
of γ-Al2O3 and reduction of Mo/Al2O3. 相似文献
92.
Thee adsorption of CO and NO on copper ion-exchanged zeolite Beta was investigated using IR method.It was found that the thermalvacuum pretreatment procedure could result in the reduction of Cu2 ions in zeolite Beta.The adsorption of CO on Cu sites in zeolite Beta closely follows Langmuir isotherm.Another Cu species may form during the reaction between water and CO.The catalytic decomposition of NO on the zeolite was observed at room temperature,indicating that the decomposition reaction may occur between two coordinated NO ligands of the same dinitrosyhc complex.Furthermore,the appearance of two series of NO adsorption bands reveals that copper ions existing at different cation sites may have different effect on the adsorption and decomposition of NO molecules. 相似文献
93.
《Analytica chimica acta》2002,458(1):95-102
An easy, fast and reliable analytical method is proposed to determine the concentration of volatile phenols (ethyl- and vinylphenols) in fino sherry wines. The technique employed is a single stage sample treatment by solid-phase extraction (SPE) following a simple, fast procedure that enables 12 samples to be extracted simultaneously and requires a small volume sample and little time. Subsequently, the extracts are analyzed by gas chromatography (GC) with flame ionization detection. The method proposed has been applied to the study of fino sherry wines affected by microbial contamination with yeasts of the Brettanomyces genus, and the relationship of these yeasts with the concentrations of volatile phenols present in this wine. 相似文献
94.
M. I. Volkova-Gugeshashvili A. G. Volkov V. S. Markin 《Russian Journal of Electrochemistry》2006,42(10):1073-1078
The thermodynamics of adsorption of amphiphilic surface-active compounds at the interface between two immiscible liquids is
considered. At the interface, these molecules are supposed to replace a few of the adsorbed molecules of both solvents. Classical
isotherms of adsorption (Frumkin, Frumkin-Damaskin, Langmuir, Henry) were based on the model of non-penetrable interface,
where an adsorbate can substitute only molecules of one solvent. At the interface between two immiscible electrolytes, nonpolar
oil/water interfaces, and liquid membranes amphiphilic molecules can substitute molecules of both solvent and classic isotherms
cannot be used. The generalization of Frumkin isotherm for permeable and non-permeable interfaces, known as the Markin-Volkov
isotherm, gives the possibility to analyze adsorption in a general case. The adsorption isotherms of pentafluorobenzoic acid
at the octane/water interface at different pHs were measured by the drop-weight method. The thermodynamic parameters of pentafluorobenzoic
acid (PFBA) adsorption at octane/water interface were determined. From the measurements of PFBA adsorption, the structure
of the octane/water interface was determined. Substitution of one adsorbed octane molecule requires approximately three adsorbed
PFBA molecules. This result shows that the orientation of solvent molecules at the interface is different from the bulk. Adsorbed
octane molecules have a lateral orientation with respect to the interface. Gibbs free energy of adsorption equilibrium and
thermodynamic parameters of PFBA adsorption show that the adsorption of PFBA at the octane/water interface is accompanied
by a reduction in the attraction between adsorbed PFBA molecules as the pH decreases to the acidic region.
Published in Russian in Elektrokhimiya, 2006, Vol. 42, No. 10, pp. 1194–1200.
The text was submitted by the authors in English. 相似文献
95.
Silica from leached chrysotile fibers (SILO) was silanized with trialkoxyaminosilanes to yield inorganic–organic hybrids designated SILx (x=1–3). The greatest amounts of the immobilized agents were quantified as 2.14, 1.90, and 2.18 mmol g−1 on SIL1, SIL2, and SIL3 for –(CH2)3NH2,–(CH2)3NH(CH2)2NH2, and –(CH2)3NH(CH2)2NH(CH2)2NH2 groups attached to the inorganic support. The infrared spectra for all modified silicas showed the absence of the Si–OH deformation mode, originally found at 950 cm−1, and the appearance of asymmetric and symmetric C–H stretching bands at 2950 and 2840 cm−1. Other important bands associated with the organic moieties were assigned to νas(NH) at 3478 and νsym(NH) at 3418 cm−1. The NMR spectrum of the solid precursor material suggested two different kinds of silicon atoms: silanol and siloxane groups, between −90 and 110 ppm; however, additional species of silicon that contain the organic moieties bonded to silicon at −58 and −66 ppm appeared after chemical modification. These modified silicas showed a high adsorption capacity for cobalt and copper cations in aqueous solution, in contrast to the original SILO matrix, confirming the unequivocal anchoring of silylating agents on the silica surface. 相似文献
96.
97.
Mariafrancesca Baratta Antonio Tursi Manuela Curcio Giuseppe Cirillo Fiore Pasquale Nicoletta Giovanni De Filpo 《Molecules (Basel, Switzerland)》2022,27(13)
Water decontamination is an important challenge resulting from the incorrect disposal of heavy metal waste into the environment. Among the different available techniques (e.g., filtration, coagulation, precipitation, and ion-exchange), adsorption is considered the cheapest and most effective procedure for the removal of water pollutants. In the last years, several materials have been tested for the removal of heavy metals from water, including metal-organic frameworks (MOFs), single-walled carbon nanotubes (SWCNTs), and graphene oxide (GO). Nevertheless, their powder consistency, which makes the recovery and reuse after adsorption difficult, is the main drawback for these materials. More recently, SWCNT buckypapers (SWCNT BPs) have been proposed as self-standing porous membranes for filtration and adsorption processes. In this paper, the adsorption capacity and selectivity of Pb2+ (both from neat solutions and in the presence of other interferents) by SWCNT BPs were evaluated as a function of the increasing amount of GO used in their preparation (GO-SWCNT buckypapers). The highest adsorption capacity, 479 ± 25 mg g−1, achieved for GO-SWCNT buckypapers with 75 wt.% of graphene oxide confirmed the effective application of such materials for cheap and fast water decontamination from lead. 相似文献
98.
Paul Kirren Lucile Barka Saher Rahmani Nicolas Bondon Nicolas Donzel Philippe Trens Aurlie Bessire Laurence Raehm Clarence Charnay Jean-Olivier Durand 《Molecules (Basel, Switzerland)》2022,27(13)
(1) Background: Due to human activities, greenhouse gas (GHG) concentrations in the atmosphere are constantly rising, causing the greenhouse effect. Among GHGs, carbon dioxide (CO2) is responsible for about two-thirds of the total energy imbalance which is the origin of the increase in the Earth’s temperature. (2) Methods: In this field, we describe the development of periodic mesoporous organosilica nanoparticles (PMO NPs) used to capture and store CO2 present in the atmosphere. Several types of PMO NP (bis(triethoxysilyl)ethane (BTEE) as matrix, co-condensed with trialkoxysilylated aminopyridine (py) and trialkoxysilylated bipyridine (Etbipy and iPrbipy)) were synthesized by means of the sol-gel procedure, then characterized with different techniques (DLS, TEM, FTIR, BET). A systematic evaluation of CO2 adsorption was carried out at 298 K and 273 K, at low pressure. (3) Results: The best values of CO2 adsorption were obtained with 6% bipyridine: 1.045 mmol·g−1 at 298 K and 2.26 mmol·g−1 at 273 K. (4) Conclusions: The synthetized BTEE/aminopyridine or bipyridine PMO NPs showed significant results and could be promising for carbon capture and storage (CCS) application. 相似文献
99.
新型含氮螯合树脂的制备及其吸附性能 总被引:1,自引:0,他引:1
以三甘醇和苯磺酰氯为原料,二乙烯三胺为交联剂合成了新型含氮螯合树脂(5),其结构经IR表征.讨论了Ni2 浓度和pH对5吸附容量的影响.动力学研究表明,5对Ni2 的吸附速率符合鲛岛公式. 相似文献
100.
The orientation of antibodies, employed as capture molecules on biosensors, determines biorecognition efficiency and bioassay performance. In a previous publication we demonstrated for antibodies attached covalently to silicon that an increase in their surface amount Γ, evaluated with ellipsometry, induces changes in their orientation, which is traced directly using Time-of-Flight Secondary Ion Mass Spectroscopy combined with Principal Component Analysis. Here, we extend the above studies to antibodies adsorbed physically on a 3-aminopropyltriethoxysilane (APTES) monolayer. Antibodies physisorbed on APTES (0 ≤ Γ ≤ 3.5 mg/m2) reveal the Γ ranges for flat-on, side-on, and vertical orientation consistent with random molecular packing. The relation between orientation and Γ is juxtaposed for silicon functionalized with APTES, APTES modified with glutaraldehyde (APTES/GA) and N-hydroxysuccinimide-silane (NHS-silane). Antibody reorientation occurs at lower Γ values when physisorption (APTES) is involved rather than chemisorption (APTES/GA, NHS-silane). At high Γ values, comparable proportions of molecules adapting head-on and tail-on vertical alignment are concluded for APTES and the NHS-silane monolayer, and they are related to intermolecular dipole–dipole interactions. Intermolecular forces seem to be less decisive than covalent binding for antibodies on the APTES/GA surface, with dominant head-on orientation. Independently, the impact of glutaraldehyde activation of APTES on vertical orientation is confirmed by separate TOF-SIMS measurements. 相似文献