J.Serb.Chem.Soc. 66(10)647–670(2001)
UDC 550.4:552.61
JSCS – 2894
Original scientific paper
The Cretaceous-Tertiary boundary Fiskeler at Stevns Klint,
Denmark: the geochemistry of the major trace metals
PAVLE I. PREMOVIC*, NIKOLA D. NIKOLIC, MIRJANA S. PAVLOVIC*,
BRATISLAV Z. TODOROVIC, DRAGAN M. DJORDJEVIC, RUZICA S. NIKOLIC,
LILIANA LOPEZ** and SALVADOR LOMONACO**
Laboratory for Geochemistry and Cosmochemistry, Department of Chemistry, Faculty of Science,
University of Nis, P. O. Box 91, YU-18000 Nis, Yugoslavia, *Vinca Institute of Nuclear Sciences,
P. O. Box 522, YU-11001 Belgrade,Yugoslavia and **Instituto de Ciencias de la Tierra Facultad de
Ciencias, Universidad Central de Venezuela, Aptdo. 3895, Caracas 1010-A, Venezuela
(Received 17 April 2001)
Trace metals in the four discrete layers of the Cretaceous-Tertiary boundary (Fiskeler) at Stevns Klint
(Denmark) are relatively well studied, yet much remains to be learned about them. Therefore, an integrated
study of the trace (meteoritic Ir, partly meteoritic Cr/Ni/Co/Au and terrestrial
Zn/Cu/La/Ce/Nd/Sm/Eu/Tb/Yb/Ta/Th) metals in the basal black marl of Fiskeler and in its (carbonate, HClsoluble, smectite, HCl-insoluble, silicate and kerogen) fractions was undertaken. The mineralogy of the marl
is comparatively simple, authigenic calcite (mainly derived from planktonic marine algae: coccoliths), detrital
Mg-smectite and quartz being the principal components, with lesser amounts of kerogen, Fe 3+-oxides,
pyrite, ilite and feldspar. Selective leaching procedures were used to establish geochemical associations
and specific mineralogical locations of the trace metals. The results identified the main locations of the major
trace metals (Cr/Ni/Co/Zn/Cu/Ir/Au). They occur mainly in the smectite and, to a lesser extent, in the
biogenic calcite (Ni/Co/Zn) and kerogen (Ir/Au). The trace metal data are in accordance with the hypothesis
that substantial proportions of Cr/Ni/Co/Zn/Cu/Ir/Au were probably contained in the detrital smectite arriving
at the site of the deposition. In a general discussion of the results, a geochemical model describing the
incorporation of trace metals in the smectite is presented, based on the weathering/trasport of the clay by
(impact-induced) acid surface waters and the adsorption of trace metal ions by the smectite particles/colloids
in the acidic solution of nearby oxic soil. The distribution/enrichment patterns of Cr/Ni/Co/Zn of the basal
black marl and higher Fiskeler layers indicate, on the other hand, that notable proportions of these metals
were incorporated into the smectite structure during the formation of the clay. The trace metal data are also
considered in light of previously published paleoecological and geochemical information for Fiskeler. It is
proposed, for example, that the local (impact-induced) superacid rainfall and wildfires played an important
role in providing appropriate humics (i.e. appropriate organics of decaying land green plants) having
porphyrin stuctures for the formation of kerogen (enriched with Cu 2+-porphyrins). In addition, it has been
suggested that the biogenic calcite with high Ni is probably a product of the metabolic uptake of boundary
seawater (enriched with this metal) by the coccoliths. The metal enrichment of the seawater was created by
a sudden and high influx of (apparently mainly meteoritic) Ni: airborne and laterally redeposited (by the acid
surface/river waters) from a nearby soil. Lastly, the lateral distribution of kerogen (enriched withCu 2+porpyhyrins) supports an earlier interpretation presented by Hultenberg1,2 that the alleged (Nye Kløv/Dania)
boundaries in northwestern Denmark represent erosion and subsequent redeposition of Fiskeler in eastern
Denmark.
Keywords: geochemistry, Cretaceous-Tertiary boundary, trace metals, smectite, kerogen.
J.Serb.Chem.Soc. 66(10)671–683(2001)
UDC 536.7+543.54
JSCS –2895
Original scientific paper
Influence of the composition of the stationary and mobile phase
on the retention factors and solvent strength parameters in RP
chromatographic systems in which the Everett equation is valid
T. J. JANJIC#, G. VU^KOVIC*# and M. B. CELAP#
Faculty of Chemistry, University of Belgrade, P. O. Box 158, YU-11001 Belgrade, Yugoslavia
(Received 28 May 2001)
It is shown how in RPchromatography the Everett equation for ideal phase equilibriums can be used to
estimate SP values (SP = log xs/x1, xs and x1 denoting the modifier mole fractions in the stationary and
mobile phases, respectively) which are in a linear dependence with the log k values. The described
procedure includes the determination of the approximate phase equilibrium constant K. By analysis of the
Everett equation it was found that in the field of x1/K there are regions of linear dependence of the SP
parameter or log k values and the mole fraction of modifiers or its logarithm. Consequently, only in these
regions it is possible for two different chromatographic systems to have the same solvent strength scale: x1
or log x1.
Keywords: Everett equation, RP column chromatography, capacity factor, SP parameter.
J.Serb.Chem.Soc. 66(10)685–695(2001)
UDC 661.847.321+661.183.8:541.128
JSCS – 2896
Original scientific paper
Alumina/silica aerogel with zinc chloride as an alkylation
catalyst
ALEKSANDAR M. ORLOVIC1#, DJORDJE T. JANACKOVIC1#, SASA DRMANIC1#,
ZORICA MARINKOVIC2 and DEJAN U. SKALA1#
1Faculty
of Technology and Metallurgy, University of Belgrade, Karnegijeva 4, P. O. Box 3503,
YU-11120 Belgrade and 2Center for Multidisciplinary Studies, University of Belgrade, Kneza
Viseslava 1a, YU-11000 Belgrade, Yugoslavia
(Received 5 April 2001)
The alumina/silica with zinc chloride aerogel alkylation catalyst was obtained using a one step sol-gel
synthesis, and subsequent drying with supercritical carbon dioxide. The aerogel catalyst activity was found
to be higher compared to the corresponding xerogel catalyst, as a result of the higher aerogel surface area,
total pore volume and favourable pore size distribution. Mixed Al–O–Si bonds were present in both gel
catalyst types. Activation by thermal treatment in air was needed prior to catalytic alkylation, due to the
presence of residual organic groups on the aerogel surface. The optimal activation temperature was found
to be in the range 185–225 ºC, while higher temperatures resulted in the removal of zinc chloride from the
surface of the aerogel catalyst with a consequential decrease in the catalytic activity. On varying the zinc
chloride content, the catalytic activity of the aerogel catalyst exhibited a maximum. High zinc chloride
contents decreased the catalytic activity of the aerogel catalyst as the result of the pores of the catalyst
being plugged with this compound, and the separation of the alumina/silica support into Al-rich and Si-rich
phases. The surface area, total pore volume, pore size distribution and zinc chloride content had a similar
influence on the activity of the aerogel catalyst as was the case of xerogel catalyst and supported zinc
chloride catalysts. Keywords: aerogel catalyst, Friedel-Crafts alkylation catalyst, sol-gel derived catalyst.
J.Serb.Chem.Soc. 66(10)697–708(2001)
UDC 546.815+628.312.5+66.061
JSCS –2897
Original scientific paper
Lead distribution in water and its association with sediment
constituents of the “Barje” lake (Leskovac, Yugoslavia)
Z. TODOROVIC1, P. POLIC2#, D. DJORDJEVIC3# and S. ANTONIJEVIC4
1Faculty
of Technology, University of Nis, Bulevar Oslobodjenja 124, Leskovac
(E-mail: todoroviczoran@yahoo.com), 2Faculty of Chemistry, University of Belgrade,
P. O. Box 158, Belgrade, (E-mail: ppolic@helix.chem.bg.ac.yu), 3Institute of Chemistry,
Technology and Metallurgy, P. O. Box 815, YU-11001 Belgrade and 4Hemofarm Concern,
Beogradski put bb, YU-26300 Vrsac, Yugoslavia
(Received 28 November 2000, revised 19 July 2001)
The lead concentrations in the water of the “Barje” lake are presented for the years 1995 to 1998. Sequential
extraction was applied to estimate the chemical association of lead in the sediments of the “Barje” lake.
Several lead fractions showed highly significant correlations with the corresponding substrate (step II: Mnoxyhydroxides; step III: Fe-oxyhydroxides) suggesting that lead carbonates were incorporated with
amorphous iron and manganese hydroxides. An explanation for this relation can be in the same
anthropogenic source of these elements.
Keywords: lead, sediments, sequential extraction, correlation analyses.
J.Serb.Chem.Soc. 66(10)709–721(2001)
UDC 546.683+546.57:543.31:628.1.033
JSCS –2898
Original scientific paper
ETAAS determination of thallium and silver from water matrix
after colloidal precipitate flotation using lead(II)
hexamethylenedithiocarbamate
KATARINA CUNDEVA, GORICA PAVLOVSKA and TRAJCE STAFILOV*
Institute of Chemistry, Faculty of Natural Sciences and Mathematics, St. Cyril and Methodius
University, P. O. Box 162, 91000 Skopje, Macedonia
(Received 6 March, revised 18 June 2001)
Afast method for the preconcentration of thallium and silver in nanogram quantities in fresh drinking waters
(source, well, tap) and waters for irrigation using colloidal precipitate flotation is described. Lead(II)
hexamethylenedithiocarbamate, Pb(HMDTC)2 played the role of flotation collector. The experimental
conditions for the successful separation of thallium and silver (mass of Pb, amount ofHMDTC -, pHof the
system, induction time, type of surfactant etc.) were optimized. After flotation separation from the mother
liquor, the solid sublate containing traces of thallium and silver was dissolved and the analytes were
determined by electrothermal atomic absorption spectrometry (ETAAS). The results of the ETAAS analysis
are compared with those obtained by inductively coupled plasma-atomic emission spectrometry. The
detection limit for thallium by this method is 0.027 _g/l, and for silver 0.005 _g/l.
Keywords: thallium, silver, determination, water, colloidal precipitate flotation, ETAAS, lead(II)
hexamethylenedithiocarbamate.
J.Serb.Chem.Soc. 66(10)723–727(2001)
UDC 681.7.062+669.228
JSCS – 2899
Note
N O TE
The STM analysis of a silver mirror surface
NEBOJSA D. NIKOLIC1, ZLATKO RAKOCEVIC2 and KONSTANTIN I. POPOV3,* #
1ICTM-Institute of Electrochemistry, Njegoseva 12, Belgrade, 2Vinca
Belgrade and 3Faculty of Technology and Metallurgy, Karnegijeva 4,
Institute of Nuclear Sciences,
Belgrade, Yugoslavia
(Received 23 May 2001)
In this work, the structure of a silver mirror surface was examined by the STM technique. It was shown that
the structural characteristics which enable a high degree of mirror reflection from this surface, which is very
close to the ideal reflectivity of silver, are: flat and mutually parallel parts of the surface which are smooth on
the atomic level, and distances between adjacent flat parts which state several atomic diameters.
Keywords: silver mirror, STM technique.