共查询到20条相似文献,搜索用时 15 毫秒
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Adsorption of Triton X-100 (TX-100) on silica gel has been studied as a function of temperature (308–328 K) and composition
for mixtures of water with ethanol or t-butanol. The adsorption capacity of silica gel for TX-100 decreases with increase
in alcohol content. Adsorption isotherms of TX-100 on silica gel are four-region and were analyzed using the ARIAN (adsorption
isotherm regional analysis) model. Data in regions 2, 3 and 4 were fitted to the Temkin, bilayer and reverse desorption isotherms,
respectively. The results show that adsorption of TX-100 on silica gel in water and alcohol-water binary mixtures occurs mainly
through formation of monolayer surface aggregates or low bilayer coverage.
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3.
Anca D. Rusu Hodorog Constanta Ibanescu Ioana Moleavin Nicolae Hurduc 《Central European Journal of Chemistry》2012,10(4):1338-1348
Thermo-sensitive polymers are of outstanding importance due to their ability to undergo controlled major changes in their properties as a response to minor modifications in temperature. The syntheses of novel polymers by grafting polysiloxane containing chlorobenzyl groups in the side chain by the homopolymerization of N,N′-dimethyl acrylamide (DMA) or the copolymerization of DMA and methyl methacrylate (MMA) using SET-LRP technique are presented. The polymers were characterized by 1H-NMR, UV, and fluorescence spectroscopy, and DSC. The thermo-sensitivity and the lower critical solution temperature (LCST), as well as the aggregation phenomena during the phase transition are evidenced by dynamic light scattering (DLS) and rheology. 相似文献
4.
Thermodynamics and kinetics of adsorption of congo red (CR) on cellulose are studied at 308–328 K. In the used concentration
range of CR, interaction of CR with cellulose is exothermic and CR molecules adsorb chemically on cellulose surface. The effects
of contact time, temperature and initial concentration of CR on kinetics of its adsorption on cellulose were investigated.
The process proceeds according to the pseudo-second-order equation. Initial adsorption rate of adsorption is first-order in
CR and the intraparticle diffusion of CR molecules within cellulose is identified as the main rate-limiting step.
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5.
This article describes the simple hydrodehalogenation of halogenated anilines and their derivatives by the action of Raney
aluminium-nickel alloy in aqueous alkaline solution at room temperature. The reaction course was monitored by means of 1H
nuclear magnetic resonance (NMR) spectroscopy and GC-MS spectra.
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6.
Rayna Bryaskova Nelly Georgieva Dimitar Peshev 《Central European Journal of Chemistry》2010,8(5):1053-1058
Polyvinyl alcohol (PVA) and tetraethoxysilane (TEOS) hybrid materials were prepared by sol-gel methods and tested as matrices
for immobilization of Trichosporon cutaneum R57, capable of removing cadmium and copper ions from aqueous solutions. A kinetic model was applied and the effects of matrix
TEOS content on the copper and cadmium uptake equilibria and rate constants were investigated.
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7.
Joanna Kurczewska Grzegorz Schroeder Urszula Narkiewicz 《Central European Journal of Chemistry》2010,8(2):341-346
The synthesis of metal (Fe, Co, Ni)-encapsulated carbon nanomaterials coated with cyclam-bonded silica has been described.
The organic layer was identified by Fourier transform infrared spectroscopy and elemental analysis. The functionalized magnetic
nanomaterials were employed to extract the divalent cations: copper, calcium, cobalt, manganese and nickel from aqueous solutions.
Their adsorption capacities were studied by the batch procedure. The concentration of cations extracted was determined by
inductively coupled plasma mass spectrometry. Influence of different parameters viz. pH, amount of the compound studied, contact
time, on the cation extraction was investigated. Under optimum conditions copper extraction was significantly more efficient
when compared with other coexisting ions.
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8.
Noora Kuuloja Tuula Kylmälä Youjun Xu Robert Franzén 《Central European Journal of Chemistry》2008,6(3):390-392
Xenbucin 1, an analgesic drug, was synthesized in 4 steps using two different routes. The biaryl fragment could successfully be produced
via a Pd/C catalysed Suzuki coupling in water using sodium tetraphenylborate as a phenylation reagent. Overall yields of the
routes were 36% and 59%, respectively.
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9.
This paper presents an experimental characterization of two sources of calcium carbonate, limestone and calcium carbonate precipitate (CCP) used in wet flue gas desulphurization processes. Characterization of the two carbonate sources was carried out by chemical analysis, IR spectra, thermal behavior, particle size distribution for CCP, BET surface area and absorption capacity of SO2 in calcium carbonate suspensions. The absorption temperature, suspension concentration and carbonate grain size were found to be the most influential parameters in the absorption capacity measurements. 相似文献
10.
Removal of lead(II) from aqueous solution with amino-functionalized nanoscale zero-valent iron 总被引:2,自引:0,他引:2
An effective adsorbent for removal of Pb(II) in aqueous solution was synthesized by reaction of nanoscale zero-valent iron
(NZVI) and 3-aminopropyltriethoxysilane (APS). The material was characterized using transmission electron microscopy (TEM),
infrared spectroscopy (IR) and a thermogravimetric analyzer (TGA). The amino-coated NZVI rapidly removed Pb(II) from aqueous
solution and was easily separated by an external magnetic field. The Freundlich equation was used for investigating the adsorption
process of APS-NZVI. Compared to untreated NZVI, the APS-coated NZVI exhibited stronger adsorption affinity and better adsorption
performance. Therefore, APS-NZVI may be a suitable material for heavy metal remediation and has potential industrial applications.
相似文献
11.
Sushilkumar A. Jadhav 《Central European Journal of Chemistry》2012,10(5):1640-1646
Two new long-chain carboxylic acids (1, 2) bearing strong fluorescent group pyrene as ligands for Self-Assembled Monolayers (SAMs) have been synthesized. The multistep targeted synthesis is accomplished by use of Pyren-1-yl methylamine hydrochloride and employing simplified synthetic protocols. Compound 2 contains a chiral center purposely introduced along the atom chain in order to make it suitable for chiro-optical studies of the resulting SAMs. 相似文献
12.
Yevgen Karpichev Hubert Matondo Illia Kapitanov Oleksandr Savsunenko Marc Vedrenne Verena Poinsot Isabelle Rico-Lattes Armand Lattes 《Central European Journal of Chemistry》2012,10(4):1059-1065
A simple and efficient protocol for the preparation of a series of N-alkyl-3-boronopyridinium salts is described which requires exposure of 3-pyridineboronic acid neopentylglycol ester and corresponding alkyle halide to microwave irradiation followed by boronic ester hydrolysis. The technique employed drastically reduces the reaction time and prevents thermal degradation and the formation of side products. Water solutions of the obtained boronopyridinium salts are shown to be stable at room temperature in wide pH range as well as in the presence of hydrogen peroxide at pH 10.0 for 72 h. 相似文献
13.
Ali Mohammad Abdul Moheman Gaber E. El-Desoky 《Central European Journal of Chemistry》2012,10(3):731-750
Several methods to determine amino acids and vitamins in biological and pharmaceutical samples have been reported. Thin layer
chromatography (TLC) finds its place when the relatively costly equipment required by other methods is unavailable. This review
covers the 1991–2010 literature on TLC/HPTLC (high performance thin layer chromatography) amino acid and vitamin determinations.
It gives an overview of the special features as well as the problems in TLC/HPTLC determinations of amino acids and vitamins.
Various chromatographic systems useful in amino acid and vitamin identification, separation and quantitation of are presented
in tabular form. Future prospects of TLC/HPTLC for amino acid and vitamin determinations are also discussed.
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14.
New chiral enantiopure ureas and thioureas with (R,R)-TADDOL backbone were synthesized. Bis-(thio)ureas with C2 symmetry were obtained from TADDOL iso(thio)cyanates and bifunctional
amino-(thio)ureas from TADDAMINE, respectively. These were tested for carboxylate recognition capacity and the association
constant was determined for the most stable complex.
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15.
Fluorescence spectroscopy and circular dichroism (CD) spectroscopy were used to investigate the interaction of coumarin-3-carboxylic
acid with human serum albumin (HSA) and bovine serum albumin (BSA) under physiological conditions in a buffer solution of
pH 7.4.
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16.
Silica gel was chemically modified with Congo red and characterized by Fourier transform infrared spectroscopy, elemental
and thermogravimetric analysis. The pH-sensitive immobilized Congo red retains the same properties as its solution counterpart
and could be applied as solid indicator. The functionalized silica gel was also employed to extract different cations from
water solutions. The concentration of cations extracted was determined by inductively coupled plasma optical emission spectrometry.
The solid support is able to selectively extract silver and copper from water solutions and retains its properties after treatment
with different organic and inorganic solvents.
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17.
Capillary electrophoresis (CE) is an attractive technique in separation science because of its high separation performance,
short analysis time and low cost. Electrochemical detection (EC) is a powerful tool for CE because of its high sensitivity.
In this review, developments of CE-EC from 2008 to August, 2011 are reviewed. We choose papers of innovative and novel results
to demonstrate the newest and most important progress in CE-EC.
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18.
Nadezhda Rangelova Lachezar Radev Sanchi Nenkova Isabel M. Miranda Salvado Maria H. Vas Fernandes Michael Herzog 《Central European Journal of Chemistry》2011,9(1):112-118
Methylcellulose (MC) / SiO2 organic / inorganic hybrid materials have been prepared from MC and methyltriethoxysilane or ethyltrimethoxysilane, and characterized
by XRD, FTIR and AFM. XRD showed peak shifts. FTIR shows intermolecular hydrogen bonding between MC and SiO2. AFM depicts surface roughness which depends on the silica precursor and MC content.
相似文献
19.
Sławomira Skrzypek 《Central European Journal of Chemistry》2012,10(4):977-988
The present review describes the recent results on the electrochemical activity of bio-guanidino compounds, such as famotidine, metformin, acyclovir, ganciclovir, zanamivir, moroxydine as well as guanidino compounds, such as S-[(2-guanidino-thiazol-4-yl)methyl]isothiourea hydrochloride, 2-guanidino-1,3-thiazole, 2-guanidinobenzimidazole. The focus is on analyzing the electrode mechanism of the guanidino compounds at the hanging mercury drop electrode and at the silver amalgam film electrode, as well as on the character of the square wave (SW) voltammetric signals. It has been stated, that the compounds can act as electrocatalysts — they are protonated and adsorbed at the surface of the electrode, after which the protonated forms of the compounds are irreversibly reduced, yielding their initial form and hydrogen. The experimental adsorption data obtained by measuring the differential capacity of the double layer, the zero charge potential, and the surface tension at the zero charge potential have established the adsorption processes underlying their electrochemical activity. The analytical application of the obtained voltammetric signals in the determination of these compounds in biological samples is also presented. This review concentrates on our own results in the context of general developments in the field. 相似文献
20.
Anna A. Rugal Vladimir M. Gun’ko Valentina N. Barvinchenko Vladimir V. Turov Tatyana V. Semeshkina Vladimir I. Zarko 《Central European Journal of Chemistry》2007,5(1):32-54
Interaction of human plasma fibrinogen (HPF) with fumed nanosilica A-300 in a phosphate buffer solution (PBS) was studied
using 1H NMR spectroscopy with layer-by-layer freezing-out of bulk and interfacial water in the temperature range of 210–273 K, TSDC
(90 < T < 265 K), adsorption, FTIR, and UV spectroscopy methods. An increase in concentration of HPF in the PBS leads to a decrease
in amounts of structured water (frozen at T < 273 K) because of coagulation of HPF molecules. Addition of nanosilica to the HPF solution strongly reduces the amounts
of structured water because of adsorption interaction of HPF molecules with silica nanoparticles, self-association of HPF
molecules, formation of denser packed hybrid agglomerates with HPF and silica, and lastly, because of conformational changes
of HPF. A monolayer adsorption capacity of A-300 corresponds to 156 mg of HPF per gram of silica. The FTIR and UV spectra
show that the HPF adsorption on silica leads to structural changes of the protein molecules. These changes and formation of
hybrid HPF/A-300 aggregates can increase the rate of clotting that is of importance on nanosilica application as a component
of tourniquet preparations.
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