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its water content can be determined;
the identification of the products
that are produced by the reaction of
NaK and components of the fuels; the
adaptation of a method for the de-
termination of CeO in NaK; and the
adaptation of a method for the de-
termination of UO, in UF,. A discus-
sion of these problems is included in
the following paragraphs.
zi reonium. An empirical volumetric
method for the determination of zir-
conium has been developed. The method
is based on the measurement of the
basicity produced by the reaction
between zirconium hydroxide and excess
potassium fluoride, which was discussed
in a previous report.(') Free acid in
the starting solution in excess of
0. 5 A' produced results approximately
2% high. This interference can be
overcome by dilution; a practical
limit at ion must be imposed, however,
because of the difficulty encountered
in determining the end point. The use
of acid media other than sulfuric acid
was also explored. Only perchlorate
systems were definitely unsatisfactory
because of excessive hydrolysis at
high ac idit y .
Another approach to the deve loprnent
of a volumetric method for zirconium
was to precipitate the hydroxide from
a mineral acid solution with excess
ammonium hydroxide, centrifuge, wash,
and dissolve in standard acid; the
excess of standard acid was determined
by titration. This method is satis-
factory in an academic sense, but is
hardly practical because ofthecopious
washing required to free the hydrous
oxide from basic salts and excess
precipitant.
The quantitative precipitation of
zirconium by benzoic acid and nitro-
benzoic acids has been reported.(2'3)
(l)R. Rowan, Jr., J. C. White, C. M. Boyd,
W. J. Ross, and C. K. Talbott, ANP Quar. Prog.
Rep. Sept. 10. 1952, ORNL-1375, p. 159.
("C, Lakshnan Rao, M. Venkataramaniah, and
Bh. S. V. Raghava Rao, J. Sei. Ind. Research
(India) IOR, NO. 7, 152-4 (1951).
(3)M. Venkataramaniah and 5h. S. V. Raghava Rao,
2. anal. Chen. 133, 248-51 (1951).
PERIOD ENDING DECEMBER 10, 1952
The reported method was used as a
basis for formulating a volumetric
method in which the precipltate is
dissolved in dilute acid, and the
liberated organic acid is extracted
with ethyl ether and determined by
titration in methyl alcohol-benzene
solution with sodium methylate by
using thymol blue as the indicator.
However, a precipitate of varyink
composition is formed, and attempts
to establish an empl rical relationship
were unsuccessful.
Further study of the reported
gravimetric methods showed low results
in all cases, the extent being de-
pendent upon the nature of the medium
of precipitation. For example, in a
sulEate system, no precipitate 1s
formed with benzoic acid because of
the strength of the zirconium sulfate
complex in solutions that are more
acid than pH 3 to 4. A slight pre-
cipitate was noted when m-nitrobenzoic
acid was used as the precipitant.
Nitric or hydrochloric acid solutions
are recommended for this procedure.
An attempt was made to titrate
zirconium m-nitrobenzoate with per-
chloric acid in ethylene glycol-
isopropyl alcohol solution. Zirconium
is not sufficiently basic in this
medium, however, to give a distinct
break in the potentiometric titration
made by using a glass electrode as
the indicator electrode and a calomel
electrode as the reference electrode.
Since mandelic acid gives a pre-
cipitate of definite composition with
zirconium, this reagent w i l l be
studied for application to volumetric
procedures.
The effect of large excesses of
uranium on the gravimetric determina-
tion of zirconium was studied briefly
in an attempt to select the precipitant
least affected. Four reagents, phenyl-
arsonic acid, mandelic acid, m-nitro-
benzoic acid, and cinnamic acid, were
tested on solutions of zirconium
containing a fivefold excess of
uranium. The number of determinations
191