Университети кимё – технология факультети

PRECESSION ADSORPTION-CALORIMETRIC INVESTIGATIONS OF 
HYBRID DYACETATE CELLULOSE-SILICA NANOCOMPOSITIONS 
Akbarov Kh.I., prof, Yarkulov A.Yu., doc, Rahmatkarieva F.G. senior res. 
National university of Uzbekistan named after Mirzo Ulugbek 
Institute of General and Inorganic Chemistry of the Academy of Sciences of the 
Republic of Uzbekistan 
On the base of analysis of literature data it is noted [1-3] that investigation of 
sorption is on threshold of new stage of development which can be characterized as 
stage of molecules visualization. To beginning of this stage conditions were 
created for experimental investigation all elemental processes carrying out on 
surface and in volume of sorbited bodies. These possibilities at present time do not 
use for elaboration theory of sorption which can allowed to describe all totality of 
its elemental stages. By this reason the quantitative forecast of behavior of sorbents 
in wide interval of sorption conditions is impossible at present time. 
For investigation of isotherms and determination of differential heats of 
water adsorption by hybrid nanocompositional polymer-silica materials has been 
used precision adsorption-calorimetric plant which equally with molar 
thermodynamic characteristics also has given full information about physical, 
chemical and crystallo-chemical nature of adsorbent surface and also about 
mechanism and thermo kinetics of adsorption and state of adsorbate in matrix of 
adsorbent. Correlation between molecular structure and thermodynamic 
characteristics was carried out for determination of number, strange and 
localization of adsorption centers, structure of nanocompositional material, 
adsorption mechanism of polar molecules of water, nature of inter molecular 

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interaction, conformation and state of adsorbited clusters and also thermokinetics 
of adsorption was investigated. 
The sharp increasing of isotherm has indicated on fact that in nanocomposite 
there are hydrophilic centers of adsorption on which rapid adsorption has carried 
out and also on homogeneity of microporouses in nanocomposites. 
Dependence of time of achievement of adsorption equilibrium from filling 
of hybrid nano compositions by molecules of water was determined. Adsorption of 
first molecules of water is solved and time of achievement of adsorptional 
equilibrium has achieved 4,5 h. then equilibrium has placed for 1,5 h. 
Differential heats of water adsorption in hybrid nanocomposite DAC-silica 
were determined. It is shown that there is a very strong energetics in this system. 
Curve of heat of water adsorption on DAC-silica material has stepped type what 
has indicated on the presence of hydrophilic centers quantity of which is equaled 
0,52 mmole/g and on which water has adsorbed with very high heat – 120 kJ/mole. 
Then forming of n-merical (H
2
O)
n
/C clusters were carried out where n=1-4; C-
hydrophylic center of adsorption. 
By equation of Gibbs-Gelmgolz the molar differential entropy of water 
adsorption in hybrid nanocomposition materials DAC-silica was calculated. 
Dependence of changing of differential entropy of water adsorption at its 
adsorption in hybrid nanocomposite DAC-silica was investigated. (for zero 
entropiya of liquid water has been accounted). 
Curve of differential mole entropy has shown that state of water on surface 
is ice-liking (entropy of ice – 26 J/mole∙K). Middle molar integral entropy of water 
retained on surface is equaled – 70,3 J/mole∙K. This value has indicated on fact 
that molecules of retained water have in great degree broke in hybrid 
nanocomposite.