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Материалы международной конференции "Глины, глинистые минералы, слоистые материалы - CMLM2009"
Physical and Chemical Properties of Clay Minerals and Layered Materials
Sorption processes of naphthalene and β-naphtole on
characterization such as X-Ray diffraction, infrared spectroscopy and nitrogen adsorption isotherms (BET).
In this presentation, we show that the amount of MgO affects the morphology and the structure of LDHs. The specific area differs for the LHDs with different compositions and is stronger for low amount of MgO. Another feature concerns the adsorption process which differs for the two organic compounds. Theβ-naphtole is ion exchanged whereas the naphthalene is adsorbed by a physiosorption mechanism. The interleaf was measured by the (003) reflection of the patterns of the LDHs and composite LDHs and changes faintly after the adsorption of the organic
compounds, which suggests the intercalation of the organic substances parallel to the leaf and a surface adsorption process.
Preliminary research of sorption of alcohols showed that alcohols reacted with LDHs by the reaction of anionic exchange.At increase of length of hydrocarbon radical, with achievement of number of atoms of carbon, equal 5, there is an increase of interlaiddistance.
The aromatic rings of the adsorbed naphthalene are disposed parallel to the inorganic layers of LDHs, regardless of concentration of active centers. The size of interlayered distance in our LDHs is about 7 Å. This size of comports with the «thickness» of aromatic ring, making 3,5 Å, while a diameter of moleculeis about 7,1 Å.
And for a phenol and b-naphtole trivial-parallel location is observed only in the initial stage of ionic exchange. An effective area of b-naphtole is 9,89 Å2, that considerably less size of one active site (~ 16 Å2), that it is possible to suppose absence of blocking of sites organic
molecules. An equilibrium, attended with the increase of interlayered distance and increase of number of active site accessible for the next molecules of b-naphtole, is set in future. This process is accompanied the increase of specific surface of LDH.
Библиографическая ссылка на эту работу:
Butenko E.Sorption processes of naphthalene andβ-naphtole on layered double hydroxides (synthetic anionic clays) // Глины, глинистые минералы, слоистые материалы - CMLM2009 - М.: Издатель И.В. Балабанов, 2009, C.200
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Материалы международной конференции "Глины, глинистые минералы, слоистые материалы - CMLM2009"
Physical and Chemical Properties of Clay Minerals and Layered Materials
Photodegradation of organic impurities induced by iron-rich clays
Glebov E.M.1glebov¤kinetics.nsc.ru,Pozdnyakov I.P.1,Grivin V.P.1,Plyusnin V.F.1,Bazhin N.M.1,Zhang X.2,Wu F.2fengwu¤whu.edu.cn
1Institute of Chemical Kinetics and Combustion SB RAS
2School of Resources and Environmental Science, Wuhan University
Clay-induced photochemistry can play an important role in self-purification of natural aqueous systems (Shichi, Takagi, 2000). Nevertheless, the nature and kinetic parameters of reactive oxygen species occurring in the processes of oxidation of organic impurities are not well known.
It was assumed (Gournis et al., 2002) that the mechanism of photolytic oxidation of organic impurities includes the formation of OH-radical. However, up to recently, this assumption has no experimental evidence.In the current work the formation of hydroxyl radical upon the photolysis of KSF was observed in the experiments on laser flash photolysis (AIG laser, 355 nm) of clay suspensions in the presence of methyl viologen dications (MV2+). MV2+was used as an acceptor of free radicals. Experiments were performed using montmorillonite KSF. The content of this clay is shown in Table 1.
Tаble 1. Major chemical composition of montmorillonite KSF (%)
SiO2 Al2O3 SO3 Fe2O3 MgO CaO
49.1 16.3 22.3 4.8 4.3 2.3
When KSF is dissolved in water, the suspension with pH 3 is formed, and iron is partially leached to the solution bulk. Both Fe(II) and Fe(III) complexes are formed in the solution. UV spectra of clay suspensions in the near UV spectral region almost coincide with that of Fe(OH)2+
complex. In the experiments on the laser flash photolysis of KSF suspensions in the presence of MV2+, kinetic curves and intermediate absorption spectrum belong to MV•(OH)2+radical cation were observed. The value of the rate constant of MV•(OH)2+formation was measured to be (3.1±0.3)×108M–1s–1. This value is satisfactorilly coinsident with the rate constant obtained by the photolysis of Fe(OH)2+homogeneous solutions and with the literature value of (•OH + MV2+)
reaction. As a result, the evidence of photolytic OH-radical formation is obtained by a direct experimental method. The coincidence of the rate constants of OH-radical formation in
suspension with that obtained in a homogeneous solution pointed to the formation of hydroxyl radical by the photolysis of Fe(OH)2+in the solution bulk. This assumption was examined in the experiments with the centrifuged samples. The removal of solid phase from the solutions did not effect on the intermediate absorption of MV•(OH)2+radical cation. Consequently, Fe(OH)2+
complexes leached from clay particles to the solution bulk are responsible for the formation of OH-radical. In the framework of practical development of this work, the experiments on the photodegradation of azo dye Orange II in the presence of montmorillonite KSF suspensions were performed. Optimal values of the photolysis conditions (concentrations of reagents and pH of solutions) were obtained. The work was supported by the Russian Foundation of Basic Research (grants №№ 08-03-00313, 09-03-00330, 08-03-92205-GFEN) and the Program of international projects of SB RAS 2009-2011 (grant №70).
Shichi T., Takagi K. (2000). Clay minerals as photochemical reactions fields. J. Photochem.
Photobiol. C: Photochem. Rev., 1, 113-130.
Gournis D., Karakassides M.A., Petridis D. (2002). Formation of hydroxyl radicals catalysed by clay surfaces. Phys. Chem. Minerals, 29, 155-158.
Библиографическая ссылка на эту работу:
Glebov E.M., Pozdnyakov I.P., Grivin V.P., Plyusnin V.F., Bazhin N.M., Zhang X., Wu F.
Photodegradation of organic impurities induced by iron-rich clays // Глины, глинистые минералы, слоистые материалы - CMLM2009 - М.: Издатель И.В. Балабанов, 2009, C.199
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Труды российских конференций
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Геология
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Материалы международной конференции "Глины, глинистые минералы, слоистые материалы - CMLM2009"