University of Southern California Dissertations and Theses

Studies on the determination of thorium in the presence of rare earths

(USC Thesis Other)

Studies on the determination of thorium in the presence of rare earths

PDF

Download

Open document

Flip pages

Download a page range

Download transcript

Copy asset link

Request this asset

Transcript (if available)

Content STUDIES ON THE DETERMINATION OF THORIUM IN THE PRESENCE
OF
RARE EARTHS
CL
3
A Thesis
Presented to
the Department of Chemistry
University of Southern California
In Partial Fulfillment
of the Requirements for the Degree
Master of Science
By
William Glenn Hubbard
May 1934
UMI Number; EP41452
All rights reserved
INFORMATION TO ALL USERS
The quality of this reproduction is dependent upon the quality of the copy submitted.
In the unlikely event that the author did not send a complete manuscript
and there are missing pages, these will be noted. Also, if material had to be removed,
a note will indicate the deletion.
UMI EP41452
Published by ProQuest LLC (2014). Copyright in the Dissertation held by the Author.
UMI
Microform Edition © ProQuest LLC.
All rights reserved. This work is protected against
unauthorized copying under Title 17, United States Code
ProQuest LLC.
789 East Eisenhower Parkway
P.O. Box 1346
Ann Arbor, Ml 48106-1346
This thesis, w ritte n under the direction of the
candidate’s F aculty Com m ittee and approved by
Date. lj . ±3 y
a ll its members, has been presented to and ac- / ‘“'N
cepted by the C ouncil on Graduate Study and I
Research in p a rtia l fu lfillm e n t of the require
ments fo r the degree of
■tary
Dean
Faculty Committee
hairman
~ j2 r ^ h / ,
ACKNOWLEDGMENTS
The writer wishes to thank Dr, Paul E. M.-P. Brinton
for his advice, kindly interest, and patience during the
time this work was in progress.
TABLE OB' CONTENTS
CHAPTER PAGE
INTRODUCTION............................ 1
I. REVIEW OP EXISTING METHODS ........ 3
II. ORGANIC COMPOUNDS FORMERLY TESTED .... 10
III. MATERIALS ....................... 12
IV. PHENYLARSONIC ACID METHOD............. 13
Procedure • ••.•••••••.•• 13
Experimental Data .••••••••• 15
Discussion 18
V. COMBINATION METHOD . . . ............. 22
Experimental Data • ••••••••• 24
VI. SUMMARY........................... 25
BIBLIOGRAPHY ............... 26
INTRODUCTION
Many writers, when mentioning the detemination of
thorium in the presence of rare earths, are prone to say,
°The separation of thorium from the other rare earths* •
That thorium is a rare earth is not true in any sense of the
word, hut the fact that it is so generally classed as one
tends to show how closely It is associated, in the minds of
chemists, with rare earths. In fact, thorium is usually
found in minerals which contain rare earths. Monazlte sand,
for example, contains from 60 per cent to 70 per cent rare
earth oxides, and from 5 per cent to 10 per cent thorium
oxide.
The chemistry of thorium is similar to that of all the
rare earths and is practically identical with the chemistry
of eerie cerium. They have the same valencej they form the
same compounds, and these compounds are usually alike as to
solubility.
It is apparent that the separation of thorium from all
of the rare earths, especially cerium, is difficult. More
over thorium compounds must be pure for their many industrial
uses, a fact which entails a complete separation from the
rare earths of the cerium and yttrium groups.
A survey of the methods for the determination of thorium
2
in monazite sand reveals the fact that the commonly used
methods are long and tedious, and require an operator skill
ed in the analysis of rare earth elements. Some of the
lesser known methods, since they show promise of being
shorter, merit an investigation to determine their accuracy.
Furthermore, a study of the existing literature shows that
few new methods have been proposed during the last twenty
years. Hence, it was decided to review some of these pro
posed methods, and to attempt to devise a shorter method,
if possible, for the determination of thorium. It was with
this fact in mind that the following study was made.
CHAPTER I
REVIEW OP EXISTING METHODS
Of the large number of methods that have been publish
ed on this subject, practically all of them are based upon
precipitating thorium as the oxalate from either a neutral
or acid solution, and subsequently igniting the precipitate
to an oxide.
If thorium is to be determined from a neutral solution,
there is a choice of the following methods.
Hydrogen Peroxide Method. The precipitation of thorium
from the neutral solution of the nitrate by hydrogen perox-
1 2
ide is described by Benz , Borelli , and Treadwell and
Hall3.
The separation of thorium takes place in the presence
of cerium and yttrium earths. If large quantities of these
two earths are present, the thorium precipitate always con
tains small amounts as impurities. Hence, two or three re
petitions must be made with this method. The precipitates
E. Benz, ”Uber die Thorium Bestimmung im Thorium.”
Ztschr. Augew. Chem., XV, (April, 1902), 297-99.
2 „
V. Borelli, Determination of thorium in monazite
sand.K Jour. Soc. Chem. Ind., XXVIII, (1929), 625.
3F.P. Treadwell and W.T. Hall, Quantitative analysis;
analytical chemistry, II. New York: John Wiley and Sons, Inc.
1925, pp. 435-437.
4
ar© gelatinous and hard to handle.
Sodium Thiosulphate Method. The separation of thorium
4
by the use of sodium thiosulphate is discussed "by Benz ,
5 6
Metzger , and Scott .
When a solution of sodium thiosulphate is added to a
neutral solution of the mixed earths, and the solution is
boiled, a yellowish precipitate of the basic thiosulphate
of thorium and of free sulphur is thrown down. This precip
itate is caused by the hydrolysis of potential thiosulphate
and the decomposition of unstable thiosulphuric acid. While
the other earths remain, for the most part, in solution, for
a complete separation, several precipitations must be made.
The conversion of the oxalate into the form of a neutral
solution each time that a precipitation is made, requires
much time.
This method, though accurate and found to give satis
factory results in the laboratories of the Welsbach Company,
at Gloucester, New Jersey, is extremely long and tedious.
Potassium Azoimide Method. The potassium azolmide
4E. Benz, 0£. cit.
5
F.J. Metzger, "A new separation of thorium from cerium,
lanthanum, and didymium, and its application to the analysis
of monazite.” Jour. Am. Chem. Soc., XXIV, (1902), 275,901.
6
v».W. Scott, Standard methods of chemical analysis, I,
4th ed., New York! D. Van Nostrand and Co., 1925, p. 523a.
5
method, precipitates thorium from a neutral solution as the
hydroxide, because of its weak basicity, according to Den-
7 8
nis , and Dennis and Kortrlght . Cerium and other rare
earths remain in solution* The reagent is hard to make and
very expensive, so that the method has found little use
commercially*
Sebacic Acid Method* Thorium can be completely separat
ed from cerium and yttrium earths, as described by Smith
9
and James , by adding a boiling solution of sebacic acid to
a neutral solution of the rare earths* The reagent is easi
ly made by heating eastor-oil soap with sodium hydroxide*
This method seems to have possibilities, but the precipitate
of thorium sebacate Is extremely hard to filter*
Lead Carbonate Method, The precipitation of thorium
from a neutral solution by pure, moist lead carbonate is
7
L.M. Dennis, "The separation of thorium from the other
rare earths.by means of potassium trinitride.* Jour. Am.
Chem. Soo., XVIII (1896), 947. .
8L.M. Dennis and F.L. Kortright, "Upon the separation
of thorium from the rare earths of the.cerium and yttrium
groups by means of potassium hydronitride." Am. Chem. Jour.,
XVI, (1894), 79.
9T.O. Smith and C. James, * A new method for the separa
tion of thorium." Jour..Am* Chem. Soc., XXXIV, (1912),
281-84.
6
described by Giles10. Again, because of its weak basicity,
thorium is precipitated as the hydroxide or basic salt,
while the rare earths remain in solution. It is claimed
that the preparation of pure lead carbonate is the chief
difficulty. Zirconium and ferric iron, if present, inter
fere.
This method seems to merit further consideration. It
is not used commercially at present.
Metanitrobenzoic Acid Method. Metanitrobenzolc acid
precipitates thorium from a neutral solution of the nitrate.
11
(See Nelsh concerning the details of this method.) Ho
difficulty is encountered with precipitation or filtration.
The precipitant is not expensive and avoids the use of alco
hol as required with certain other organic reagents. Of the
three nitrobenzoic acids, the meta acid is used because it
is the most soluble in water. This reagent need not be
absolutely pure because the ortho and para acids, as well as
benzoic acid, act in a similar manner.
12
Fumaric Acid Method. As described by Metzger , thorium
is precipitated as thorium fumarate from a 40 per cent alco
10W.B. Giles, "The estimation and separation of thoria
from the yttrium-cerium group of oxides.” Qhem. Hews, XCII,
(1905), 1-3 and 30-31.
11 »
A.C. Helsh, "A new separation of thorium and cerium,
lanthanum, and didymium by metanitrobenzoic acid." Jour. Am.
Chem. Soc., XXVI, (1904), 780.
^2F.J. Metzger, op. cit.
holic solution. Thorium and fumaric acid react, molecule
for molecule, whereas no change is produced by that reagent
in solutions of cerium, lanthanum, or didymium. A reprecip
itation removes the traces of rare earths carried down
with the thorium. This method is thought to he shorter
than the thiosulphate method.
Ammonium Oxalate Method. Determination of thorium as
thorium oxalate is based upon its solubility in an excess of
i % 14
ammonium oxalate. (See Glaser .) It is claimed by Benz
15
and Brauner that the yttrium earths are precipitated in
completely. The method is long and should be employed, if
at all, only when high thorium and low rare earth content
are present.
The preceding paragraphs have mentioned most of the
more common methods for precipitation of thorium in a neu
tral solution. There are fewer methods for the precipita
tion of thorium in an acid solution. The advantages over
the methods mentioned are speed, ease of manipulation, inex
pensive reagents, and accurate separation of thorium from
13C. Glaser, "Estimation of thoria; chemical analysis
of monazite sand.” Jour. Am. Chem. Soc., XVIII, (1896;
782-95. -
14
E. Benz. 0£. cit.
15
Bohuslav Brauner, "Contributions to the chemistry of
thorium; comparative research on the oxalates of the rare
earths." Trans. Chem. Soc., LXXIII, (1898), 951-85.
8
cerium and yttrium earths* The many steps in making a neu
tral solution, and the many reprecipitations, with long
standing before filtration are avoided*
The following methods are described for precipitating
thorium from an acid solution.
Potassium Iodate Method, This method depends upon the
fact that, in the presence of a large excess of potassium
iodate, thorium iodate is rendered insoluble in mineral
acids, whereas iodates of the other rare earths are soluble.
The reagent is expensive, but this is counterbalanced by the
speed of determination. (See Meyer and Speter^6.)
Hypophosphate Method. This method depends upon the
fact that in an acid solution thorium can be precipitated
by sodium hyp ©phosphate, as thorium hyp opho sphat e. Zircon
ium and titanium Interfere. The reagent is expensive and
hard to make, and cannot be used in sulphuric acid solution,
1*7
since cerium may also be precipitated. (See Levy and
16R.J. Meyer and M. Speter, "Determination of thorium
in monazite sand.1 * Chem. Aba., IV, (1910), 1586.
17
S.I. Levy, "The rare earths, their occurrence, chem-
istry, and technology." 2nd ed. New ^ork: Longmans, Green
iHtco.— 9217------ -
18
and Spencer .)
Sodium Pyrophosphate Method. This is the Carney and
Campbell19 method used by the Lindsay Light Company, Chi
cago, Illinois, where it has proved entirely satisfactory
as to its accuracy.
Thorium is precipitated as the pyrophosphate and is
successively changed to the sulphate, the hydroxide, the
chloride, and the oxalate. The method Is rather long, since
the same procedure is carried through twice.
Phenyl arson! c Acid Method. This method, as described
20
by Rice, Fogg and James , precipitates thorium as the
phenyl arson ate in a strong acetic acid solution, while the
rare earths remain in solution. The reagent is easily made,
and the time of operation, short.
18
J.F. Spencer, The metals of the rare earths. Hew
York: Longmans, Green and Co., 1919.
19
R.J. Carney and E.D. Campbell, *A new method for the
determination of thorium in monazite sand.r t Jour. Am. Chem.
Soc.. XXXVI, (1914), 1134-1143.
pO
A.C. Rice, H.C. Fogg and C. James, "Phenylarsonic acid
as a reagent for the determination of thorium in monazite
sand.” Jour. Am. Chem. Soc., XLVIII, (1926), 900-902.
CHAPTER II
ORGANIC COMPOUNDS TESTED FOR PRECIPITATION OF THORIUM
Below is given a list of some of the organic compounds
that have been tested, with varying success, as a precipitant
for thorium.
Urea- no precipitate.
Thiourea- no precipitate.
Acetamide- no precipitate.
Semi Carbazine- no precipitate.
Succinimide- partial precipitation.
Diethylamine- precipitates thorium, cerium, lanthanum,
and didymium.
Maleic acid- no precipitate.
Cinnamic acid- partial precipitation in 20 per cent al
coholic solution.
Picric acid- partial precipitation in alcoholic solution.
Phthalic acid- partial precipitation in 50 per cent al
coholic solution.
Metzger1.
Phenoxyacetic acid- precipitation almost quantitative.
Orthonitrophenoxyacetic acid- unsatisfactory.
Mucic acid- partial precipitation.
Anisic acid- partial precipitation.
Aspartic acid- unable to filter precipitate.
Pyrotartaric acid- precipitation quantitative.
Oxanilic acid- precipitate easily dissolves in slight
excess acid.
Oacodylic acid- no precipitate.
— Smith and James .
Gallic acid- quantitative, slimy precipitate.
Tannic acid- quantitative precipitation.
i
S1F.J. Metzger, 0£. cit.
Op '
T.O. Smith and C. James, op. cit.
11
Citric acid- precipitates all from acetone solution.
Salicylic acid- precipitates thorium, soluble in excess.
Oleic acid- precipitates thorium and cerium.
Linoleic acid- precipitates all.
Paratuolic acid- precipitates thorium.
Oxyisophthalic acid- precipitate nearly quantitative.
Benzoic acid- precipitates thorium.
Neish23.
^A.C. Nelsh, 0£. olt.
CHAPTER III
MATERIALS
Monazite Sand. A standard sample of monazite sand from
Travancore, India, was procured through the courtesy of the
Lindsay Light Company of Chicago, Illinois.
Another standard sample of monazite from Brazil was
obtained through the courtesy of Dr. H.S. Miner, chief chem
ist of the Welsbach Company, Gloucester, New Jersey.
Thorium Nitrate. Pure thorium nitrate was obtained
through the courtesy of the Welsbach Company.
Fhenylarsonic Acid. The phenylarsonic acid was prepar
ed for Dr* E.H.M.-P. Brinton by the department of organic
chemistry at the University of Minnesota.
CHAPTER IV
PHENYL ARSONIC ACID METHOD
Of the methods described previously for the determina
tion of thorium in monazite sands, the one using phenylar-
24
sonic acid, as published by Rice, Fogg, and James , was
chosen for this investigation, since no report of the exper
iences of others with the method was found in the literature.
Procedure Recommended. Twenty-five grams of the sand
are digested with 50 ml. of concentrated sulphuric acid for
12 hours on a hot plate. When cold, the mixture is slowly
added to 500 mL. of ice cold water and thoroughly stirred.
The small residue of sand, etc., is removed by filtration,
and the filtrate is made up to a liter.
The phosphoric acid is removed in the following manner:
15 ml. of concentrated nitric acid are added to a 100 ml.
portion of the solution, and the mixture then poured into a
hot solution of about 10 g. of oxalic acid. After the whole
has stood for a short time, the precipitate is filtered off,
washed, and then decomposed by boiling with concentrated
nitric acid. When the volume has reached about 15 ml. vol-
24A.C. Rice, H.G. Fogg, and C. James, 0£. cit.
14
ume, an excess of hot oxalic acid. (10 g.) in solution is
added, and the whole diluted to ahout 200 ml. After filter
ing, the precipitate is again dissolved in concentrated
nitric acid and evaporated almost to dryness.
The residue is treated with ahout 300 ml. of water and
all eerie cerium reduced by the careful addition of sulphur
ous acid. The solution is heated to boiling, treated with
30 ml. of 10 per cent phenylarsonic acid solution and 75 ml.
of glacial acetic acid. This is followed by the slow addi
tion of a concentrated solution of ammonium acetate, until
it is evident that all of the thorium phenylarsonate is pre
cipitated, after which the mixture is digested on a hot plate
for about ten minutes. The precipitate is then filtered off,
washed, dissolved in 30 ml. of lsl hydrochloric acid, the
solution is diluted to about 300 ml. and again treated with
a little sulphurous acid. The thorium is repreeipitated by
adding a few milliliters of phenylarsonic acid, 75 ml. of
acetic acid, and enough ammonium acetate to insure complete
precipitation.
This last precipitate is then dissolved in 30 ml. of
1:1 hydrochloric acid, the solution treated with 5 g. of
oxalic acid, and the whole diluted to about 200 ml. This is
allowed to stand for at least 12 hours* The precipitate is
filtered, washed well with acidulated water, and ignited to
the oxide.
15
Experimental Data. A solution of pure thorium nitrate
containing approximately ten grams per liter was made up. It
was standardized by precipitating 25 ml. of solution as the
oxalate, and this was ignited to the oxide. Three determi
nations gave the following results:
TABLE I
Standardization of Thorium Nitrate Solution
25 ml. solution ThOp determined
Sample No. 1 0.1719 g.
Sample No. 2 .1725 g.
Sample No. 5 .1725 g.
This gave a value of 0.0069 g. of ThOg per ml. of
solution.
Next, four samples of 25 ml. each were taken, and the
following procedure was tried. The thorium nitrate was pre
cipitated as thorium phenyl arson ate, dissolved in hydrochlor
ic acid, and precipitated as thorium oxalate. It was then
Ignited to the oxide In porcelain crucibles.
16
TABLE II
Precipitation of Thorium with Phenylarsonic Acid.
25 ml. solution Th0o determined
Sample No. 1 0.1721 g.
Sample No. 2 .1722 g.
Sample No. 3 *1718 g.
Sample No* 4 .1726 g.
Average of the four determinations was 0.1722 g. ThOg,
This checked with the results which had been obtained
by determining thorium directly as the oxalate, Indicating
that phenylarsonic acid precipitates thorium quantitatively
as thorium phenyl arsonate.
Two 50 ml. samples of a solution, which had been pre
viously digested according to the Lindsay Light Company's
official method, were treated according to the phenylarsonic
acid method, with the following results:
TABLE III
50 ml. solution ThOp determined
Sample No. 1 0.2187 g.
Sample No. 2 .2191 g.
This gave 8'.75 per cent Th0g. The accepted analysis of
this sand was 8.86 per cent Th0o.
M
17
A 25 g. sample of Brazilian monazite sand was digest
ed in 50 ml. of pure concentrated sulphuric acid, and the
25
procedure specified by Rice, Fogg, and James was followed
exactly throughout.
TABLE IV
50 ml. solution ThOp determined
Sample No. 1 0.1871 g.
Sample No. 2 .1878 g.
Average .1875 g.
These results gave 7.50 per cent ThOg. The accepted
analysis of this sand was 6,57 per cent ThOg. These samples
showed by their color that they contained some cerium.
It was noticed that a precipitate formed in the filtrate
when attempting to separate the thorium oxalate from the
phosphates, early in the procedure. This precipitate did
not go through the filter paper; It formed upon standing or
after dilution. Sufficient precipitate formed each time the
method was tried to justify its examination as to eontent.
Some of this precipitate was dissolved in acid and a
qualitative analysis was run. Cerium was found. Thorium
was also indicated after adding phenylarsonic acid. Lines
25
A.C. Rice, H.C• Fogg, and C. James, op. cit.
18
indicating neodymium and praseodymium were observed in the
spectrum. These tests proved that some of the rare earths
were toeing held in solution because of the high concentra
tion of acid used to prevent the phosphates from precipitat
ing.
With this in mind, three portions from this same sam
ple were treated in the following manner:
To sample No. 1, no acid was added; the total acidity
was that of the sulphuric acid used in digestion.
To sample No. 2, one-half the specified amount of nitric
acid was added.
To sample No. 3, the specified amount of nitric acid
was added.
The oxalates were then precipitated and ignited to
determine the amount of total rare earth oxides. The results
follow:
TABLE V
50 ml. solution Ss^3 ^e^ermlne<3 -
Sample No. 1 0.6266 g.
Sample No. 2 .5777 g.
Sample No. 3 ,5424 g.
This work proved that the high concentration of acid
was keeping some of the rare earth oxalates in solution.
Discussion. From this study of the Phenylarsonic
Acid Method, the following conclusions were reached:
19
1. That it is impossible to make a 10 per cent solution
of the phenylarsonic acid* Beilstein gave the following
solubilities in water
Temperature Solubility 100 g. Hg0
28° G. 3.25 g.
41° C. 4.82 g.
52° C. 8*52 g.
84° C. 24.00 g.
A saturated solution at room temperature is approxi
mately a 3 per cent solution.
2. That phenylarsonic acid does precipitate thorium
quantitatively from solution.
3. That the acid concentration used in this method is
such as to keep some of the rare earths in solution as
oxalate.
4. That this high concentration of acid is necessary
to keep the phosphates in solution.
5. That this method, involving less handling of pre
cipitates and neutralizing of solutions, is shorter than
many of the other methods.
6. That the precipitate of thorium phenylarsonate
should not be digested on the hot plate for longer than 10
or 15 minutes. After a long and continued heating, the
solution containing the precipitate turns brown in color,
indicating decomposition. The precipitate also changes
from a white flocculent to a grey crystalline substance.
20
If this grey precipitate is dissolved in hydrochloric acid
and oxalic acid, very little thorium oxalate crystallizes
from the solution,
7. That the defect in this method lies in the separa
tion of the rare earths from the phosphates, A reduction
in acid concentration allows the phosphates to precipitate,
and there is no provision made for removing them later,
when they interfere with the phenylarsonate precipitation,
8, That the method must be altered if it was to be
usable. Two means suggested themselves. One was to reduce
the concentration of acid sufficiently to allow all the
rare earths and some of the phosphates to come down. The
latter must then be removed later in the process. The
other means was to choose another method for separating the
rare earths and phosphates.
The latter procedure was decided upon. The Carney and
26
Campbell method of separating thorium from the rare
earths and phosphates was employed. Then, instead of de
composing the thorium pyrophosphate by means of sulphuric
acid and nitric acid in a Kjeldahl flask, it was fused
with sodium peroxide in a nickel crucible. This fusion
requires but five minutes, whereas dissolving the sulphates
26
R.J. Carney and k.D. Campbell, 0£. cit.
21
from the decomposition of the pyrophosphates in sulphuric
acid is sometimes a slow process. The method, as worked
out, follows in detail in Chapter V.
CHAPTER V
COMBINATION METHOD
A 25 g. air-dried sample of the sand is weighed and
transferred to a porcelain casserole of 500 ml* capacity*
Fifty milliliters of pure sulphuric acid are added and the
sand well stirred. The casserole is then covered with a
watch glass and the contents digested on a hot plate for
12 hours* The mixture should he stirred frequently to in
sure complete decomposition. The temperature maintained
should he such that no spattering occurs, hut fumes of the
oxides of sulphur are given off* After digestion, the mass
is allowed to become cold. The sulphates and unattacked
sand is then transferred, in small portions, to a beaker
containing finely crushed ice. After thorough stirring
the whole is allowed to come to roam temperature. The un
digested sand is filtered off and the solution diluted to
a liter.
A 100 ml. sample is transferred to a liter beaker and
made up to a volume of 450 ml* with distilled water. Five
milliliters of concentrated hydrochloric acid are added and
the solution heated to boiling. A slight excess of sodium
bisulphate is added to reduce the cerium and iron. Fifteen
milliliters of sodium pyrophosphate solution (50 g. per
23
liter) are added from a pipette* The solution is boiled for
5 minutes and filtered immediately. The precipitate is
washed with acidulated water and allowed to drain*
The paper and precipitate are transferred to a nickel
crucible and ignited until the filter paper is destroyed*
An excess of sodium peroxide is added and the impure thorium
pyrophosphate fused at a low temperature* Quiet fusion
takes place if excessive heat is avoided. The crucible and
contents are allowed to cool and are placed in 100 ml, of
distilled water to dissolve the excess sodium peroxide.
The precipitate consists of thorium hydroxide and nickel
oxide. The liquid is brought to boiling and the precipitate
is filtered immediately and washed with hot water.
The precipitate is dissolved in as small an amount of
concentrated nitric acid as is possible and then evaporated
nearly to dryness. The residue is treated with about 300
ml. of distilled water, heated to boiling, and sodium bi
sulphite again added to reduce any traces of iron and cerium.
Thirty milliliters of a saturated phenylarsonic acid solu
tion and 75 ml. of glacial acetic acid are added. This is
followed by the slow addition of a saturated solution of
ammonium acetate, until it is evident that all of the thor
ium phenylarsonate has been precipitated. The mixture is
digested on a hot plate for 10 minutes and is filtered.
This precipitate is dissolved in 30 ml. of 1:1 hydro
24
chloric acid and poured into 50 ml. of a hot concentrated
solution of oxalic acid and diluted to 200 ml. The oxalate
precipitate is boiled for 15 minutes and is digested on the
water bath for several hours. The precipitate is filtered
through a quantitative filter paper and is washed with
acidulated water containing oxalic acid. The thorium oxa
late, in a tarred crucible, is ignited to the oxide and
weighed as thorium oxide.
Experimental Data. The Combination Method was tested
by running three 50 ml. samples of Brazilian monazite sand.
The first sample was a portion of the same sample that had
been used previously as mentioned in Chapter IV.
Samples No. 2 and 5 were taken from a new 25 g. sample
of the same sand.
All three samples were treated as previously outlined
by the Combination Method. The following results were ob
tained;
TABLE VI
50 ml. solution Grams ThOg Per cent ThO„
Average of three samples
Sample No. 1
Sample No. 2
Sample No. 3
0.1664
.1629
.1632
6.64$
6.52$
6.53$
6.56$
The accepted analysis was 6.57 per cent ThOg.
CHAPTER VI
SUMMARY
Many of the methods for determining thorium in mona-
zite sand have heen reviewed and their defects pointed out.
Some of these methods have heen checked and discussed in
detail. It is believed from the results quoted above, L -
by combining parts of the Carney and Campbell Pyrophosphate
Method and the Rice, Fogg and James Phenylarsonic Method,
that a shorter and simpler one may be worked out.
BIBLIOGRAPHY
Benz, E., "Uber die Thorium Bestimmung im Thorium." Ztschr.
Angew. Chem., XY, (April, 1902), 297-99.
Borelli, V., "Determination of thorium in monazite sand."
Jour. Soo. Ohem. Ind., XXVIII, (1929), 625.
Brauner, Bohuslav, "Contributions to the chemistry of
thorium; comparative research on the oxalates of the
rare earths. Trans. Chem. Soc., LXXIII, (1898),
951-85.
Carney, R.J. and Campbell, E.D., *A new method for the
determination of thorium in monazite sand." Jour. Am.
Chem. Soo., XXXVI, (1914), 1134-43.
Dennis, L.M., "The separation of thorium from the other
rare earths by means of potassium trinitrlde." Jour.
Am. Chem. Soc., XVIII, (1896), 947.
Dennis, L.M. and Kortright, P.L., "Upon the separation of
thorium from the rare earths of the cerium and yttrium
groups by means of potassium hydronitride." Am. Chem.
Jour., XVI, (1894), 79.
Giles, W.B., "The estimation and separation of thoria from
the yttrium-cerium groups of oxides." Chem. News,
XCII, (1905), 1-3, 30-31. .
Glaser, C., "Estimation of thoria; chemical analysis of
monazite sand." Jour. Am. Chem. Soc., XVIII, (1896),
782-93. .
Levy, S.I., The rare earths, their occurrence, chemistry,
and technology, 2nd ed. New York: Longmans, Green and
Co., 1984.
Metzger, P.J., "A new separation of thorium from cerium,
lanthanum, ~and didymium, and its application to the
analysis of monazite." Jour. Am. Chem. Soc., XXIV,
(1902), 275 and 901. .
Meyer, R.J. and Speter, M., "Determination of thorium in
monazite sand." Chem. Abs., IV, (1910), 1586.
27
Neish, A.O., "A new separation of thorium from cerium, lan
thanum, and didymium by metanitrobenzoic acid.” Jour.
Am. Ghem. Soc., XXVI, (1904), 780.
Rice, A.G., Fogg, H.C., and James, C., ”Phenylarsonic acid
as a reagent for the determination. of thorium in mona
zite sand.1 1 Jour. Am. Ghem. Soc., XLVIII, (1926),
900-902.
Schoeller, W.R. and Powell, A.R., The analysis of minerals
and ores of the rarer e arths. London: C. Griffin and
Go., 1&L9.
Scott, W.W., Standard methods of chemical analysis, 4th ed.
New York:"” ! ) 1 . Van Nostrand and Co., 192^' I'J 523a.
Smith, T.O. and James, C., new method for the separation
of. thorium.” Jour. Am. Ghem. Soc., XXXIV, (1912),
281-84.
Spencer, J.F., The metals of the rare earths. New York:
Longmans, Green and Go., 1919.
Treadwell, F.P. and Hall, W.T., Quantitatlve analysis:
analytical chemistry, 7th ed. New York: J. Wiley and
Sons, 1928. II , “"435-37.

Linked assets

University of Southern California Dissertations and Theses

Conceptually similar

PDF

A study of the Mohr and Volhard methods of determination of chloride content in brines

PDF

Rapid microchemical field anaylses for ores of the rare elements

PDF

Studies on the ignition of Lanthanum oxide

PDF

Nitrosyl chloride as a nonaqueous solvent

PDF

A critical study of the methods for the quantitative determination of beryllium

PDF

Kinetic and mechanistic studies of the redox reaction of Pt(CN) 4XYn in aqueous solution

PDF

The action of boron fluoride on trimethylammino sulphur trioxide, ammonium acetate, ammonium sulfate, and potassium sulfate

PDF

Study of the separation of uranium from the rare-earths by the oxalate method

PDF

Studies on the solubility of beryl after thermal treatment

PDF

The purification and conductance of sodium tetradecyl sulfate

PDF

The addition compound of phosphorous oxide and boron trifluoride

PDF

The chemistry of boron trichloride in liquid sulfur dioxide

PDF

The possibility of higher oxides of lanthanum

$Preparation of different modifications of sodium soaps and their characterization by X-ray diffraction$

PDF

Preparation of different modifications of sodium soaps and their characterization by X-ray diffraction

PDF

The determination of free alkali or free fatty acids in soaps

PDF

The construction and use of a strong electromagnet in certain chemical studies

PDF

A study of the molybdate of cerium as a means of separation from the other rare earths

PDF

The determination of the dielectric constant and dipole moment of Ethyl salicylate

PDF

Studies on the organophilic montmorillonites

PDF

Studies on nitrilophosphoric halides.

Asset Metadata

Creator Hubbard, W. G (author)

Core Title Studies on the determination of thorium in the presence of rare earths

Degree Master of Science

Degree Program Chemistry

Publisher University of Southern California (original), University of Southern California. Libraries (digital)

Tag chemistry, inorganic,OAI-PMH Harvest

Language English

Contributor Digitized by ProQuest (provenance)

Permanent Link (DOI) https://doi.org/10.25549/usctheses-c17-785014

Unique identifier UC11349280

Identifier EP41452.pdf (filename),usctheses-c17-785014 (legacy record id)

Legacy Identifier EP41452.pdf

Dmrecord 785014

Document Type Thesis

Rights Hubbard, W. G.

Type texts

Source University of Southern California (contributing entity), University of Southern California Dissertations and Theses (collection)

Access Conditions The author retains rights to his/her dissertation, thesis or other graduate work according to U.S. copyright law. Electronic access is being provided by the USC Libraries in agreement with the au...

Repository Name University of Southern California Digital Library

Repository Location USC Digital Library, University of Southern California, University Park Campus, Los Angeles, California 90089, USA