Without doubt the lifework of Agu Aarna carried out to promote oil
shale industry in Estonia has raised the research in this field to the
top of world science [1, p. 23].
Estonian oil shale industry did not emerge from emptiness. The
honor of being the initiator of processing of this combustible natural
resource belongs to Scotland, where James Young patented the method of
getting paraffins and oils [2, p 18].
The year 1838 is considered the beginning of research on Estonian
oil shale. In this year Member of Academy Helmersen described oil shale
samples from Vanamoisa in "Mining Journal" published in
St-Petersburg [2, p. 21].
Agu Aarna started his activity in oil shale research even before
graduating from Tallinn University of Technology in 1948. His first
publications dealt with investigations on improving methods for cleaning
retort gas of tunnel ovens [3, p. 19]. Further developments in this
field resulted in writing the candidate's thesis; he obtained the
degree of candidate of technical sciences in 1948 already.
Scientific heritage of this outstandingly fruitful researcher deals
with genesis, chemical composition, and thermal treatment of kukersite
oil shale as well as chemical and technological properties of thermal
treatment products. He with co-workers has published more than 100
papers . His thoroughness led his passionate researcher's nature
to ever deeper understanding of chemical processes.
We know that even in the middle of the last century oil shale
chemists were convinced that the essence of thermal decomposition of oil
shale organic matter (kerogen) is a gradual thermolysis, during which
benzine fraction forms only at heavy oil cracking. Agu Aarna and his
co-workers explained the chemism of oil shale thermal decomposition
differently demonstrating that heavy oil and semicoke are the end
products of the process. The knowledge is extremely important when
designing technological equipment for oil shale processing. Even more -
a detailed investigation of kerogen, its carbon-skeleton structure and
functional groups was needed. The results obtained together with his
co-workers E. Lippmaa and K. Urov were essential at optimizing the
operation of industrial retort units.
Agu Aarna studied the composition and properties of shale oil for a
long time . The methods for determination of oxygen compounds in oil
elaborated by his team are in general use even today. The developed
analytical methods (incl. chromatographic ones) enabled to get a full
picture of the distribution of oil shale oxygen-containing functional
groups between phenol, carbonyl, carboxyl and so-called unknown
Further research together with L. Molder and E. Siimer enabled them
to draw the conclusion that shale oil is a complicated polyazeotropic
system with no major component.
At the beginning of the 1960s Agu Aarna together with K. Kiisler
and P. Christjanson focused on investigation in the field of DFK resins.
The original idea about carrying the reaction out in the presence of a
complex former served as a basis for taking the next step directed to
industrial production of DFK resins. The results were patented and put
into use in several countries.
Considerable is the contribution of A. Aarna in the field of
thermodynamics of solutions of autoassociating compounds (together with
L. Molder, E. Siimer, A. Suurpere, A. Viikna and others).
Being a prominent scientist, Agu Aarna was also a well-known
science popularizer. He has written more than 200 popular papers dealing
mostly with topical problems of chemical science and industry.
Such a rich scientific heritage in the field of an experimental
science could not have arisen without brilliant organizing capacities.
We can state that many of his prophetic ideas have been developed by
contemporary analytical possibilities.
[1.] A. Aarna. Estonian Soviet Encyclopedia. Vol. 1.--Tallinn:
Valgus, 1985. 704 pp.
[2.] A. Aarna. Oil Shale.--Tallinn: Valgus, 1989. 142 pp.
[3.] Publications of Agu Aarna 1947-1975 / L. Molder, I. Tali
(Eds.).--Tallinn, 1975. 79 pp.