1382
SLIZHOV et al.
intervals for saturated, unsaturated, and aromatic
hydrocarbons and aliphatic alcohols when applying
chelate from solution (Table 3). Slightly lower values
are observed for Silipor and Chromaton modified with
iron(III) acetylacetonate. In the synthesis of the chelate
directly on the support surface the sorbents based on
Chromaton with nickel and iron acetylacetonates are of
close selectivity factor within noted homologous series;
in the case of using Silipor the sorbent with Fe(AA)3
exceeds that with Ni(AA)2.
the sorbents based on Chromaton with combined phases
of polyethylene glycol 20M and acetylacetonates was
discussed in [7].
CONCLUSIONS
(1) It was shown that the retention time of the test
compounds (benzene, ethanol, methyl ethyl ketone)
by sorbents Chromaton N and Silipor 075 modified
with chelate compounds of Ni(II), Fe(II), Zn(II)
acetylacetones depends on the nature of the support,
the technique of applying the chelate and the ability of
metal ion to the donor-acceptor interactions
The studies found that the modification of
Chromaton with metal chelates with the thermal fixing
fuser does not alter the pH of the surface, at the same
time, the chromatographic data indicate a significant
improvement in retention parameters. It should be
noted that the method of pH-measurement can estimate
the average surface acidity as a manifestation of the
cumulative effect of interaction of the two sets of the
sites with water: of acids and bases (both Lewis or
Brønsted). The Hammett indicators adsorption method
from aqueous media was used for the differentiation
of the acid-base sites on the surface of thermally
modified samples of Chromaton [6]. Analysis of the
spectra (Fig. 4) points to the dominant character of
the base sites on the surface of sorbents under study
that is due to the chemical nature of Chromaton.
Introduction of acetylacetonates does not change this
trend, and, moreover, increases the number of sites of
acid and neutral nature that affects the chromatographic
characteristics of the sorbents, in particular, the increase
in Kovats retention indices (Table 2). For researching
the possibility of blocking the base sites of Chromaton
a layer of polyethylene glycol 20M was applied to the
surface. Therewith a significant reduction in the number
of surface basic sites was established by an indicator
method (Fig. 4, curve 2). Thus, when using Chromaton
as a support, prior application of layers blocking its base
sites is appropriate that can affect the donor-acceptor
activity of chelates. The study of acid-base properties of
(2) It was found that synthesis of acetylacetonates
directly on the support surface leads to a significant
change in the acid-base surface properties of Chromaton
NandSilipor075andtomoreactivityinthemanifestation
of various types of intermolecular interactions than in
application of chelate from a solution followed by heat
treatment.
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RUSSIAN JOURNAL OF APPLIED CHEMISTRY Vol. 86 No. 9 2013