Scholars' Mine Scholars' Mine
Masters Theses Student Theses and Dissertations
1967
Studies in coprecipitation of trace amounts of elements Studies in coprecipitation of trace amounts of elements
Gerald Delano Schucker
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STUDIES IN COPRECIPITATION OF TRACE AMOUNTS OF ELEMENTS
BY
GERALD DELANO SCHUCKER - I e,.,
A
THESIS
submitted to the faculty of
THE UNIVERSITY OF MISSOURI AT ROLLA
in partial fulfillment of the requirement for the
Degree of
MASTER OF SCIENCE IN CHEMISTRY
Rolla, Missouri
1967
Approved by
(advisor)
ABSTRACT
A new approach to preconcentration of trace amounts of elements
has been demonstrated whereby traces of metals tied up as chelates
are coprecipitated on a column of solid organic material. Complete
coprecipitation was found to occur within very narrow pH ranges,
thereby allowing separation as well as concentration of the elements
by careful adjustment of acidity and concentration of chelating
agent. The separation is based on the difference in stability
constants of the metal chelates. Preliminary studies with different
physical forms of the carrier precipitate, indicate adsorptive
processes could play a significant role in the mechanism of the
column-coprecipitation process.
The applicability of Atomic Absorption Spectrophotometry for
the determination of traces of metals in coprecipitation studies
has been investigated. Sensitivity limits for nine elements have
been established and the effect of certain organic reagents on
their standard curves determined. A new quantitative indirect
method for the determination of trace amounts of chelating agent
.has been descri~ed.
TABLE OF CONTENTS
LIST OF FIGURES LIST OF TABLES
• Ill ................... ,.. •••••••• «> •
.............................. I.
II.
III.
IV.
v.
INTRODUCTION e • • e o • • • • • • o • • • e • * • • • • • • • • o • • • o • • • • • • • •
REVIEW OF LITERATURE ............................... QUANTITATIVE MEASUREMENT OF TRACE COMPONENTS ••••••••
A.
B.
Determination of Trace Amounts of Metals . ........ . 1. Experimental
a. Reagents . b. Apparatus c. Standards
............................... ............................... ............................. 4 • • ...............................
2. Results and Discussion • •••••••••••• Ill'"' ••••••
a. Detection Limits ..................... "" .... b. Effect of Organic
Indirect Determination of . ............ . Materials
Trace Amounts
1. 2 ..
of Chelating Agents ........................... Experimental . ......................... . Results and Discussion . ..................... ""'.
COLUMN-COPRECIPITATION STUDIES • ................. •· •• ill ..
A.
B.
General Experimental Procedure for Coprecipitation ••••••••••••••••••••••••••••••
Results and Discussion •••••••••••••••••••••••·• 1. 2.
Oxine-Phenolphthalein System . ............. ., .. Oxine-2-Naphthol System ................. it ••••
CONCLUSIONS ......................................... BIBLIOGRAPHY ............. ,. ............ "' .... ,. ...... . APPENDIX ................................. ., ...... "" ... . ACKNOWLEDGMENTS ...................................... VITA ..................................................
1
4
9
9 9
20
39
iv
LIST OF FIGURES
Figure Page
1. Effect of Organic Materials on Standard Curve
for Zinc ••••••••••••••••••••••••••••••••••••••••••• 13
2. Attenuation of Copper Absorption Signal by Oxine •••
3. Effect of pH on Percentage Coprecipitation of
Copper Oxinate at a 1000 Fold Oxine and Phenol-
17
phthalein as Carrier ••••••••••••••••••••••••••••••• 22
4. Effect of pH on Coprecipitation Recovery and Sep-
aration of Four Metals with Oxine and 2-Naphthol •• , 30
5. Percentage Coprecipitation of Cadmium Oxinate as a
Function of Amount of Excess of Complexing Agent .. ' 33
6. The Coprecipitation Recovery of Silver with Oxine
and 2-Naphthol ••••••••••••••••••••••••••••••••••••• 37
?.
8.
9.
10.
11.
).2.
13.
14.
15.
16.
Standard Curve for Manganese •••••••••••••••••••••••
Standard Curve for Cobalt ••••••••••••••••••••••••••
Standard Curve for Cadmium .. ........................ Standard Curve for Cadmium . ........................ Standard Curve for Nickel .......................... Standard Curve for Silver .......................... Standard Curve for Lead ............................ Standard Curve for Zinc ............................ Standard Curve for Copper . ......................... Standard Curve for Gold ............................
46
47
48
49
50
51
52
53
54
55
LIST OF TABLES
Tabl.e
I. Retention of Trace Amounts of Copper Oxinate by
Phenolphthalein using 1000 fold Excess Oxine ••••••••
II. Effect of Carrier Weight on the Coprecipitation of
Copper Oxinate using phenolphthalein and a 1000 fold
Excess Oxine •••••••••••••••••••••••••••••••••••••••
III. A Comparison of the Coprecipitation Ability of Solid
Phenolphthalein to that Re-precipitated from an
Alcoholic Solution •••••••••••••••••••••••••·•••••••
IV. Retention of Trace Amounts of Copper Oxinate by
2-Naphthol using 1000 fold Excess Oxine ••••••••••••
V. Retention of Trace Amounts of Cobalt Oxinate by
2-Naphthol using 1000 fold Excess Oxine •·••••••••••
VI. Retention of Trace Amounts of Cadmium Ox:inate by
2-Naphthol using 1000 fold Excess Oxine ............. VII. Retention of Trace Amounts of Manganese Oxinate by
2-Naphthol using 1000 fold Excess Oxine ............... VIII. Correlation of Chelate Stability Constants with
Experimental pH~ Values ••••••••••••••••••••••••••••
IX. The Relative Percent Absorption of Standard
Solutions of Gold as a Function of pH ••••••••••••••
X. Instrument Parameters ••••••••••••••••••••••••••••••
v
1
I. INTRODUCTION
The importance of trace amounts of inorganic ions in chemical,
physical, and biological systems has come to the forefront in the
past decade. Analytical chemists have been called upon to analyze
for many elements at the part per million and even part per billion
levels. Satisfactory methods are usually available for the deter
mination of microgram amounts of most ions, but in many instances
separation and concentration of the trace elements from large
amounts of the matrix or major constituent is often a necessary
preliminary step in their quantitative determination. Chemical
enrichment procedures often employed include: chromatography, ion
exchange, solvent extraction, and precipitation with organic re
agents. The phenomenon of coprecipitation using either inorganic
or organic coprecipitating agents has rec.eived extensive study as
a preconcentration technique.
When the quantity of an element in solution is less than that
required to exceed the solubility product, direct precipitation is
impossible. However it has been shown previously by several
workers that small quantities of metal ions tied up as chelates
can be extracted (coprecipitated) from aqueous solution by solid
organic carrier precipitates (4,23,30). The use of these organic
coprecipitants permits one to extend the limits of application of
organic precipitation to solutions of lower concentration of the
elements to be precipitated. For example, at a dilution of 1:107
2
nickel is not precipitated by 8-hydroxyquinoline (oxine). However
when 2-naphthol is used as a coprecipitant, complete coprecipitation
of the nickel oxinate takes place.
In previous coprecipitation work, the usual method of adding
the carrier precipitate to the aqueous solution of trace metal and
chelating agent has been from a solution of the carrier in an organic
solvent. This study is devoted to an investigation of a new method
of using the carrier precipitate.
There is strong reason to believe that freshly precipitated
fine-grained organic precipitates could be made the basis of a
column technique whereby metal ions tied up as chelates could be
extracted (coprecipitated) on the column in the presence of an
excess of the chelating agent. It is then possible that a selective
separation of the metals can be made by elution with various pH
buffered solutions and/or various concentrations of the chelating
agent.
Therefore the purpose of this study was to determine the
feasibility of a new approach to preconcentration of trace elements,
column-coprecipitation, by investigating the retention and elution
of trace element complexes on columns of organic coprecipitants.
Also to be investigated was the applicability of Atomic
Absorption Spectrophotometry for the quantitative determination
of trace amounts of metals in coprecipitation studies.
The significance of this work stems from the need for better
methods to accurately measure ultramicro quantities of elements
which have recently been shown to be so important in such fields
as geochemistry, pure materials research, ie., semiconductors,
3
superconductors, nuclear reactor materials, etc., and in biological
systems.
4
II. REVIEW OF LITERATURE
One of the earliest workers to use the phenomenon of co-
precipitation for the concentration of trace amounts of elements
was Mitchell (23). Using 8-hydroxyquinoline as the complexing
agent with various other metal oxinates as carrier precipitates,
and later (24) in combination with tannic acid and thionalid, he
was successful in quantitatively precipitating many trace elements
of biological importance in plant materials and soil extracts.
Several modifications of this method appeared later (1-3,25-27,29).
In 1954 V.I. Kuznetsov began an extensive series of articles
entitled "Organic Coprecipitants" (4-20). He employed a variety
of techniques or mechanisms of the coprecipitation process in
developing practical analytical methods for the concentration of
trace elements, particularly from soils and natural waters. If
for example an element is capable of forming a complex anion, he
found a good carrier precipitate would be the salt of a large
organic cation having low solubility, high molecular weight, and
containing the same anion that was used for forming the complex
anion of the element. Bismuth in the form of an iodide complex
anion Bii4 , is quantitatively coprecipitated by a precipitate of
methyl violet even at dilutions of 1:108 • Conversly, if an element
forms a complex cation such as Me(o-phenanthroline); , the carrier
precipitat~ should be a heavy organic anion.
Kuznetsov also investigated the concentration of trace amounts
of metals, tied up as chelates, by the use of "indifferent copre-
cipitates", that is, organic molecules that are structurally
dissimiliar to the chelating molecule. He compared the use of
these indifferent coprecipitants to liquid extraction and termed
it "extraction by solid solvents". This comparison was later
studied in detail by Tappmeyer (30) in an attempt to obtain a
quantitative correlation of solid coprecipitation to liquid ex-
traction. Using various chelating systems and metal ions it was
shown that the factors influencing coprecipitation of the metal
chelates with indifferent coprecipitants were the same as those
that influence solvent extraction. Metal chelates that were ex-
tracted well with solvents like CC14 were also extensively
coprecipitated with organic coprecipitants. Excellent agreement
was found between experimental plots of percent coprecipitation
vs. pH and calculated plots using the same type of equilibrum
5
considerations used in solvent extraction. Results thus indicate
that factors which influence the extent of coprecipitation of
metal chelates with organic carriers can be combined into one
unified expression which is quantitatively identical to the ex-
pression used for the equilibria involved in extraction of metal
chelates by organic solvents:
-1
G H+J ~ H+j-l D = KfKd K~ . + k. K. .
x ~ R ~ ~ HR aq aq
where ki and Kf = first and total formation constants of the
given chelate
Ki = ionization constant of the chelating agent
n = charge on the metal
6
HR = concentration of chelating agent in the aq
aqueous phase
Kdx = distribution coefficient of the chelate
between the organic and aqueous phase
D = distribution ratio of the metal between
the two phases
Weiss and co-workers (21,32-36) have studied the co-
crystallization of trace quantities of elements from solution
by organic reagents, however their technique required only one
reagent and simplified the operating procedure by direct
crystallization of the reagent from solution. They claim the
coprecipitation process follows Fajans Rule which predicts that
the crystallized organic reagent will be enriched with the trace
element if the trace element and organic reagent combine to form
a compound whose insolubility is greater than that of the reagent
alone. Therefore the rule could be used as a basis for the
selection of organic compounds for cocrystallizing an element from
very dilute solution. The studies by Weiss indicate many diverse
elements could be cocrystallized with organic reagents. Analytical
methods were devised for the determination of many of these elements
in seawater.
In., the work by Weiss, the mechanism is probably different
from "indifferent coprecipitation" and doubtless involves ion-
exchange of the trace metal ion for one of the cations of the
organic reagent. This ion-exchange type mechanism is also
advanced by Troiskii (31) to explain the coprecipitation of trace
metals with inorganic compounds such as metal sulfides, hydroxides,
7
and for the isolation of radioactive elements by coprec
He found that full coprecipitation of the microcomponent does
indeed occur when the solubility product of the microcomponent is
smaller than that of the corresponding coprecipitant. This
has been confirmed for many elements with various coprecipitanta.
However there have been several exceptions noted where the
rule was inapplicable and coprecipi tation was neither coaplete no:r:
selective thus indicating the apparent adsorptive nature o! co
precipitation.
Although most of the literature concerning coprec tat ion
reports on work directed toward the development of prac
analytical methods, a few studies concerning mechanisms of oo.
precipitation of organic chelates on organic precipitates have
been carried out. Williams ( 37), working under condi tion.a that
the solubility of the metal chelate had definitely not been ex
ceeded, proved that true coprecipitation does occur. Moreover
his studies revealed that the microcomponent is extracted by a
metastable liquid phase and then mechanically trapped by the
carrier during precipitation. Since the carrier precipitate was
found to release appreciable quantities of the trace element on
aging, occlusion appeared to be the principle mechanism.
It should be noted that the aboye transient liquid mec
is only applicable to experiments where the carrier preci tate
is added from an organic solvent and would not be a factor in the
present study where organic solvents were not used.
Williams further concluded that: (l) the efficiency of' co
precipitation is directly proportional to the fraction of metal
8
complexed (E = KF) ; (2) the percentage coprecipitation is depend
ent upon the method of precipitation of the carrier ; (3) adsorp
tion of the microcomponent by the carrier contributes little to
the total amount coprecipitated.; (4) the amount of chelating
agent coprecipitated influences the amount of chelate coprecipitated.
The great amount of literature dealing with coprecipitation
by inorganic compounds, such as, metal hydroxides, sulfides,
calcium phosphate, germanium dioxide, tungstic acid, calcium
oxalate, etc., has not been surveyed in this work because of the
difference in mechanism. In these cases adsorption, ion-exchange,
and collodial phenomenon are doubtless the prominent factors. It
is difficult to see how the mechanism proposed for the coprecipitation
of lead ions by barium sulfate can apply for example to the co
precipitation of traces of metal oxinates with phenolphthalein.
A survey of the literature did not reveal any attempt at the
separation and concentration of trace elements using a chelating
agent and a column of solid organic coprecipitant. The present
work was initiated to study this new approach.
III. QUANTITATIVE MEASUREMENT OF TRACE COMPONENTS
A. Determination of Trace Amounts of Metals
A necessary prerequisite in any investigation of preconcen
tration techniques is an accurate analytical method for the
determination of ultramicro quantities of metals. Previous
workers studying coprecipitation have primairly used emission
spectroscopy, colorimetric methods, or radioisotopes. Each of
these techniques have several disadvantages. Emission spec
troscopy although a good general survey tool, lacks precision
and accuracy. Colorimetric methods generally are applicable for
only one element at a time and often require time consuming wet
ashing procedures to destroy organic matter. Radioisotopes,
perhaps the most sensitive method for ultratrace work, require
special facilities for handling radioactive materials.
Within the past decade, a new instrumental technique, Atomic
Absorption Spectrophotometry, has been developed for trace metal
analysis. Part of the purpose of the present work was to in
vestigate the usefulness of Atomic Absorption for coprecipitation
studies.
1. EKperimental
The sensitivity limitations of Atomic Absorption were
investigated for the elements of interest in coprecipitation
stadies by preparing calibration curves in the lowest concen
tration ranges for which accurate absorption measurements could
be obtained. The influence of organic reagents upon these curves
was determined.
9
a. Reagents. All reagents used were of reagent grade and
were employed without further purification. Stock solutions
10
(1 mg./ml. of metal ion) of Cuso4 .5H2o , CoC12 .6H2o , CdC12 ,
MnC12 .4H2o 9 Ni(N03 ) 2 .6H20 , Pb(No3 ) 2 , Zn(N03 ) 2 .6H20 , and AgN03
were pre.pared by dissolving the salts in distilled water.
Suitable aliquots of each of the stock solutions of the first
four and last four elements were mixed and diluted to a volume
of one liter so that the resulting two mixed stock solutions
contained ten micrograms of each element per milliliter. A dilute
solution of Gold of the same concentration was prepared by
dilution of a stock solution containing 3.5 g./1. Auc13 • The
chelating agent, 8-hydroxyquinoline (exine), was prepared at
various concentrations in acetic acid. Phenolphthalein and
2-naphthol were used in powder form.
b. Apparatus. All Atomic Absorption measurements were made
on a standard Perkin Elmer Atomic Absorption Spectrophotometer,
Model 303, using the air-acetylene single slot burner head and
null meter readout.
~. Standards. Solution standards were prepared covering the
concentration range .02~10 ppm by dilut~on of proper aliquots of
the two mixed metal stock solutions. Calibration curves were then
prepared for each element by measuring the relative percent
absorption of each of the standard solutions at the appropriate
wavelengths. Instrument parameters used are given in Table X.
To study the effect on the standard curves of the organic
reagents used in the coprecipitation studies, additional sets of
standard solutions were prepared, one using water which had been
saturated with phenolphthalein and others containing various
amounts of 8-hydroxyquinoline.
2. Results and Discussion
11
In coprecipitation studies the concentration of metal ions
must be kept sufficiently low as to not exceed the solubility
product constant of the metal chelates, otherwise precipitation
not coprecipitation would be taking place. A study of this sort
is therefore largly limited by the analytical method by which the
quantities of the trace components are determined.
a. Detection Limits. Figures (7-16) show the calibration
curves for the elements of interest in the concentration ranges
for which the most accurate absorption measurements could be
obtained using the most sensitive instrument settings. Concen
tration values are plotted against percent absorption or absorbance
depending on which gave the most linear curve. The lowest optimum
working ranges were found to be: (1) Cd and Zn .01-0.1 ppm (2) Cu,
Co, Mn, Ag, Au 0.1-1.0 ppm (3) Pb and Ni 1-10 ppm.
b. Effect of Organic Materials. In order for the copre
cipitation phenomenon to occur on solid organic carrier precipitates,
the:metal ions must first be tied to a large organic molecule. An
excess of various chelating agents, such as oxine, have been used
for this purpose. The effect on the accurate determination of the
trace amounts of metals by approximately a 50 fold excess of oxine
was investigated by preparing the series of solution standards to
contain 1 ml. of a 5% solution of oxine. Experiments were conducted
on a solution containing Cu, Zn, Cd, and Mn. The curves for Co, Cd,
and Mn were found to be identical with those prepared from solutions
12
containing no exine. However the relative percent absorption
values for copper and zinc were suppressed. This was found to be
caused by precipitation of the copper as the oxinate from the
solution standards of high concentration, with the possible co
precipitation of zinc hydroxide. These results are resonable in
light of the very high formation constant of copper oxinate (105
higher than any of the other metals), and the amphoteric nature of
zinc. Since zinc is known to precipitate as the hydroxide at
about the optimum pH for coprecipitation (about 5.5), it was ex
cluded from study by this technique. Copper on the other hand
could be used in the absence of zinc at concentrations not to
exceed 50 micrograms.
The lowest optimum working range for lead and nickel was found
to be 1-10 ppm. This would necessitate carrying out the copre
cipitation studies of these two elements at an order of magnitude
higher concentration levels than for the other elements. Experiments
showed that solution standards containing no visible precipitate
could not be obtained for these elements above the range O.l-1 ppm.
Therefore lead and nickel, because of their poor sensitivities, had
to be excluded from study using Atomic Absorption as the means of
quantitative determination.
The column-coprecipitation technique involves the passage of
aqueous solutions of metal chelates over a column of solid organic
material. Since phenolphthalein, one of the materials used, is
slightly soluble in water, its effect on the accurate determination
of the traces of metals was determined. Figure 1 shows that the
small amount of dissolved phenophthalein had no effect on the
calibration curve for zinc. All the other elements of interest
.20
.16
Q)
(.) .12 c:: t1l
.0 !-< 0 fl.l
~
.08
.04
13
0 standards in distilled water
~ standards containing phenolphthalein
0.2 0.4 0.6 0.8 1.0 Zinc Concentration, ppm
Figure 1. EFFECT OF ORGANIC MATERIALS ON STANDARD CURVE FOR ZINC
were investigated and the presence of dissolved phenolphthalein
found to be negligible.
B. Indirect Determination of Trace Amounts of Chelating Agent
14
For the quantitative determination of small amounts of chelating
agents during coprecipitation studies, previous workers (30,37)
have used ultraviolet absorption spectrophotometry. The present
study has defined a new analytical technique. During the invest
igations of the effect of oxine on the calibration.·curves of the
various elements, it was observed that an t1indirect" quantitative
method, using Atomic Absorption Spectrophotometry, could be set
up for the determination of trace amounts of chelating agents.
In aqueous solutions, oxine forms chelate complexes with
metals which can be extracted into organic solvents. Since the
amount of particular metal extracted is governed by the concen
tration of the chelating agent, a direct relationship can be
obtained between the reduction in the atomic absorption signal for
the metal in the aqueous phase and the concentration of the chelating
agent.
1. Experimental
Since 8-hydroxyquinoline is an ampholyte, close control of
the pH is very important in the extraction or precipitation of the
jydroxyquinolates. In the present work the system was buffered to
a pH of 6.5 with acetate.
A measured excess of metal ion (about 10 ppm copper solution
was used in this study) was added to s.eparatory funnels. Various
amounts of oxine in acetic acid solution were then added covering
15
the concentration range of about 0-5 ppm, and the pH brought up
to 6.5 by the addition of solid ammonium acetate. The aqueous :
phases were then extracted with methyl isobutyl ketone and placed
in volumetric flasks. The organic layers were washed with a
dilute solution of ammonium acetate and the washings added to the
flasks. The solutions were diluted to volume, mixed, and the
relative percent absorptions measured.
2. Results and ~iseussion
Figure 2 shows the linear attenuation of the absorption
signal for the aqueous solution of copper as the amount of oxine
is increased. Since the chelating agent reduces the amount of
absorption of metal in direct proportion to its concentration,
this indirect method can be used to quantitatively measure trace
amounts of chelating agent.
Alternately, the amount of absorption of the organic phase
could have been measured and the concentration of chelating agent
related to the increase in metal signal. Generally the sensitivity
of determinations performed in organic solvents is greater than
those in aqueous solutions. However at the time of this work, the
Atomic Absorption unit was not equipped to aspirate organic solvents.
Copper was the only metal used in this aspect of the present
study. Others should suffice, provided their hydroxyquinolates are
soluble in the organic solvent employed. Other solvents such as
chloroform or ethyl acetate could probably be used, however Sandell
(28) points out that the hydroxyquinolates of Ga, Mg, W, Ag, and Au
are not extractable into chloroform and those of Cd,and Zn precipitate
16
out of the chloroform phase as they become hydrated.
No study was made to determine the optimum conditions for
complete extraction of the metal because this indirect technique
is the reverse to that usually used in solvent extraction in that
an excess of metal ion is added rather than of chelating aga.nt.
As long as the conditions of extraction are held constant, it is
unimportant for the maximum amount of metal to be extracted.
In all probability this technique could be extended to many
other chelating agents. The concentration ranges of the species
being determined can easily be extended by varying the amount of
excess metal present.
17
14
12
c:1o 0
·.-I 4-J p. 1-l 0 Ul
~ 4-J d 8 <lJ (.)
1-l <lJ
p..,
<lJ >
•.-I 4-J C\1
,....; 6 <lJ
P:i
4
2
5 10 15 Ho1arity Oxine x 106
20 25
Figure 2. ATTENUATION OF COPPER ABSORPTION SIGNAL BY OXINE
18
IV. COLUMN-COPRECIPITATION STUDIES
Previous workers (30,37) have studied the coprecipitation of
trace amounts of metals using various combinations of chelating
agent and carrier precipitate. Their work has shown the oxine
phenoEphthalein and oxine-2-naphthol systems m be very good in
producing complete coprecipitation. These systems were therefore
chosen for studies in the feasibility of a column-coprecipitation
technique. Experiments were performed to determine the factors
affecting the retention and elution of metal"oxinates on columns
of solid organic carrier precipitates (coprecipitants).
where
From the equation
Me+n
Me+n + n RKe ----- Me(Ke) n
= metal ion of oooidation
+ + n R
number
~e = organic chelating agent
Me(Ke) n = metal chelate
R+ = hydrogen ion
Equation (l)
n '
it is apparent that the concentration of the chelating agent and
the pH are very important factors in the coprecipitation pr&cess
if it is the metal chelate species that is being coprecipitated.
Therefore these two factors (and others) were examined in an
attempt to obtain the concentration/separation of metals by a
column-coprecipitatian technique.
19
A. General Experimental Procedure for Coprecipitation
Standard solutions of Cu, Co, Cd, and Mn (10 mcg./ml.) were
prepared by dilution of suitable stock solutions. Oxine was
dispensed from standard solutions containing 100, 50, and 5 milli
grams per milliliter in acetic acid.
Test solutions were prepared by adding to 75 ml. of distilled
water, 20 meg. of one of the above metals, and the desired level
of excess exine. The pH was then adjusted by the addition of dilute
HCl or NH4oH. In no case was there a visible sign of a precipitate
forming since the metal concentration was so small. A blank
solution was also prepared containing the same ingredients except
t~ metal ions.
A polyethylene holder tube with an end filter disc was packed
with three grams of the carrier precipitate (in some experiments
the carrier precipitate was used directly from the reagent bottle
and in others it was freshly prec&pitated from alcoholic solution).
The column of coprecipitant was conditioned by passing through it
about 20 ml. of the blank solution, the filtrate being discarded.
Next the test solution was passed through at a rate of about
1 ml./min. with the aid of suction. The column was then washed
with 10 ml. of the blank solution. The test solution and washings
were collected in a 100 ml. volumetric flask and made up to volume
with distilled water. The amount of metal escaping coprecipitation
was determined by measuring the relative percent absorption of
the solutions , using Atomic Absorption, and converting to concen
tration of metal by using the standard curves.
B. Results and Discussion
Nearly 100 pieces of data were taken under a variety of
conditions for the two carrier precipitate systems. Various
experimental conditions were investigated such as the amount
of earrier used, physical form of the carrier, oxine concen
tration and the pH.
1. Oxine-phenolphthalein system
Table I shows the data obtained for the coprecipitation
20
of copper oxinate using a 1000 fold excess oxine and a column of
solid phenolphthalein as carrier, in which the pH was varied and
the percentage retention determined by Atomic Absorption. The
same data is presented graphically in Figure 3 and shows a
symB!etrieiH sigmoid curve when percent coprecipi ta tion is plotted
vs. pH. A maximum percentage retention of only 63% was attained.
In an attempt to increase the percent of metal retained,
experiments were carried out on the amount and physical form of
the carrier precipitate. Table II shows the non-dependence of
percent coprecipitation on carrier weight when the quantity of
material used to make up the column is varied from 1 to 5 grams.
Apparently gram quantities of carrier are well in excess of the
amount needed to coprecipi tate all the metal oxinate •
As the adsorptive properties of the carrier precipitate may
play a significant role in the column-coprecipitation technique,
attempts were made to obtain a column of very fine-grained phenol
phthalein by freshly precipitating it from an alcoholic solution'.
pH
4
4.5
5
5.5
5.75
6
6.5
7
TABLE I.
RETENTION OF ~RACE AMOUNTS OF COPPER OXINATE BY PHENOLPHTHALEIN USING 1000 FOLD EXCESS OXINE
Quantity of Qua11tity Found Metal Taken, meg. in Filtrate, meg.
20 18.8
20 18.6
20 18.0
20 16.4
20 12.0
20 8.6
20 7.8
20 7.4
21
Percent Retained
6
7
10
18
40
57
61
63
c 0
·.-(
.u cO .u ·.-(
0.. ·.-(
0 Q)
~ 0.. 0 ()
.u c Q)
0 ~ Q)
A-1
22
70
60
50
40
30
20
10
4 5 6 pH
7 8
Figure 3. EFFECT OF pH ON PERCENTAGE COPRECIPITATION OF COPPER OXINATE AT A 1000 FOLD OXINE AND PHENOLPHTI~LEIN AS CARRIER
TABLE II.
EFFECT OF CARRIER WEIGHT ON THE COPRECIPITATION OF COPPER OXINATE USING PHENOLPHTHALEIN AND 1000 FOLD EXCESS OXINE
Grams of carrier used % Coprecipitation
1 60
2 60
3 61
4 6o
5 60
pH 6.5
23
24
Results were unsucessful because the very fine and gummy-textured
precipitate could not be transfered to the column apparatus.
When the phenolphthalein solid phase is formed by precipitation
from alcoholic solution, the very fine precipitate begins to
coagulate almost immediately. After standing for about 20 minutes
this material was collected on the column and used for coprecipitation
of copper oxinate. Table III indicates that a phenolphthalein
precipitate prepared in this manner is less effective in its co
precipitation ability than solid phenolphthalein used directly from
a reagent bottle. Apparently coagulation had extensively decreased
the available surface area, thus indicating the possibility that
adsorption is an important factor in the column-coprecipitation
process. Since the percentage retention of copper oxinate using
phenolphthalein as carrier could not be improved, a more effective
carrier for the column technique was sought.
2. Oxine-2-Naphthol system
Tables IV-VII show the pH vs. percentage coprecipitation data
for four metal oxinates using a 1000 fold excess oxine and 2-naphthol
as carrier. The percentage retention of copper was substantially
increased over that using phenolphthale~n; complete retention was
obtained for the other metals. A summary of th~ data is presented
in Figure 4 accentuating the concentration/separation possibilities
existing for the four metals. Since the coaplete coprecipitation
takes place within very narrow pH ranges, it is possible to separate
the metals by careful adjustment of acidity. The anomalous behavior
of copper oxinate was not totally unexpected in light of the
TABLE III.
A COMPARISON OF THE COPRECIPITATION ABILITY OF SOLID PHENOLPHTHALEIN TO THAT PRECIPITATED FROM ALCOHOLIC SOLUTION
pH:f of Solution
4
5
6
% Coprecipitation
Phenolphthalein Solid precipitated
Phenolphthalein from Alcohol
6 6
10 7
57 29
20 meg. copper, 1000 fold oxine
25
pH
1
2
2.5
2.75
3
3.1
3.25
3.5
TABLE IV.
RETENTION OF TRACE AMOUNTS OF COPPER OXINATE BY 2-NAPHTHOL USING 1000 FOLD EXCESS OXINE
Quantity of Metal Taken, meg.
20
20
20
20
20
20
20
20
Quantity Found in,Filtrate, meg.
20
18.6
14
10
3.6
2.8
3.0
9.0
Percent Retained
0
7
30
50
82
86
85
55
26
pH
2.0
3.0
3.2
3.4
3.6
3.8
4.0
5.0
TABLE V.
RETENTION OF TRACE AMOUNTS OF COBALT OXINATE BY 2-NAPHTHOL USING 1000 FOLD EXCESS OXINE
Quantity of Quantity Found Percent Metal Taken, meg. in Filtrate, meg. Retained
20 20 0
20 19 5
20 15.2 24
20 11 45
20 7.4 63
20 4.2 79
20 0 100
20 0 100
27
pH
3.0
3.5
4.0
4.5
4.6
4.7
4.8
4.9
5.0
5·5
6.0
7.0
TABLE VI.
:RETENTION OF TRACE AMOUNTS OF CADMIUM OXINATE BY 2-NAPHTHOL USING 1000 FOLD EXCESS OXINE
Quantity of Quantity Found Percent Metal Taken, meg. in Filtrate, meg. Retain.ed
20 20 0
20 20 0
20 20 0
20 20 0
20 14 30
20 12 40
20 10.6 47
20 8.0 80
20 0 100
20 0 100
20 0 100
20 0 100
28
pH
4.0
5.0
5.2
5.4
5.6
5.8
6.0
TABLE VII.
RETENTION OF TRACE AMOUNTS OF MANGANESE OXINATE BY 2-NAPHTHOL USING 1000 FOLD EXCESS OXINE
Quantity of Quantity Found Percent Metal Taken, meg. in Filtrate, meg. Retained
20 20 0
20 18 10
20 8.4 58
20 1.0 95
20 0.5 97.5
20 0 100
20 0 100
29
80
c: 0
•r-l ~
60 C1l ~ •r-l p.
•r-l 0 Q)
1-l p. 0 u. ~ c:
40 Q)
u 1-l Q)
p.,
20
0 copper
A cobalt
0 cadmium
• manganese
2 3 4 5 6 7 pH
Figure 4. EFFECT OF pH ON THE COPRECIPITATION RECOVERY ANJ) SEPARATION OF FOUR METALS WITH OXINE AND 2-NAPHTHOL \}I
0
31
difficulty experienced by other workers (27) in attaining complete
coprecipitation by the usual alcoholic coprecipitation procedure.
In order to increase the versatility of the column-coprecip-
itation technique, experiments were conducted on the effect of
various levels of excess exine on the percentage coprecipitation.
Figure 5 shows the data obtained for cadmium oxinate at three
different concentration levels of exine. By adjustment of exine
level, the pH range for complete coprecipitation can be shifted
along the pH axis thus allowing additional opportunity for effecting
separation of the metals. The other oxinates would be expected to
exhibit the same general type of behavior upon changes in the
chelate concentration.
The ability Gic separate metal chelates by this method appears
to be directly related to the chelate stability constants. From
equation (1) we can define an equilibrum constant Km as follows:
Km [M(Ke)J [H+] n
= F _____ f _____ Me+n] HK3 n
Equation (2)
Km = ---~-c~~J~---[HKe]n
Equation (3)
where Dm represents the distribution ratio for the metal.
The distribution coeffic~ent is then given by:
Dm Equation (4)
32
Writing equation (4) in logarithmic form:
log Dm = log Km + n log HKe + n pH
When the percent of metal extracted (coprecipitated) is 50%
the first term is equal to zero. If we consider a constant excess
of reagent (HKe), and define p~ as the pH of 50% extraction,
at half extraction we have:
1 plL, = - log Km + log HKe
!2 n
Thus the pH at half extraction is a constant and for the same
concentration of a given chelating agent the magnitude of the p~
is dependent only on the valence of the ion (n) and the stability
constant. For a series of metals having the same valence, pH~
should vary directly with the chelate stability constant, and
the magnitude of the value should indicate the order of stability
of the chelates. From equation (4) it is apparent that the more
stable the chelate thelower will be the pH of 50% extraction.
Table VIII shows the correlation of stamility constants for
the chelates used in this study with the experimentally obtained
p~ values (taken from Figure 4). There is good qualitative agree
ment and the order of stability is shown to be:
Cu > Co > C d > Mn
This agrees with the work of Mellor and Maley {22) who have shown
that the stability of the complexes .of bivalent metail. ions follows
the order
Pd > Cu :> Ni > Pb > Co> Zn > Cd > Fe> Mn > Mg
irrespective of the nature of the ligands involved.
80
t:l 0
•.4 -1-1 <U
-1-1 60 •.4 p.
•.4 (,) 4) 1-1 0. 0 u
-1-1 40 t:l 4) (,)
1-1 (I)
Il-l
20
0 1000 fold oxine
~ 500 fold oxine
[J 100 fold oxine
2 3 4 5 6 7 pH
Figure 5. PERCENTAGE COPRECIPITATION OF CADMIUM OXINATE AS A FUNCTION OF AMOUNT OF EXCESS OF COMPLEXING AGENT
TABLE VIII.
CORRELATION OF CHELATE STABILITY CONSTANTS WITH EXPERIMENTAL p~ VALUES (pH of half coprecipitation)
pH~ (exp)
Cu(ox) 2 23.4 2.?5
Co(ox)2 17.2 3.45
Cd(ox) 2 13.4 4.75
Mn(ox) 2 12.6 5.20
* Taken from "Stability Constants of Metal-Ion Complexes" by Sillen, L.G., and Martell, A.E., Chem. Soc. (London) Spc. Publ. No. 17 (1964)
35
It has been demonstrated that the column-coprecipitation
technique can be useful in the concentration and separation of
important transition metals. Another aspect of the present
study was to investigate its potential for the recovery of
precious metals from very dilute solutions. Test solutions,
containing 0.2 ppm silver were prepared and carried through the
coprecipitation procedure previously described.. Figure 6 shows
that complete recovery was obtained using 1000 fold excess oxine
(based on AgOx) with 2-naphthol as carrier. Attempts to apply
the same method to dilute solutions of gold failed due to the
standard solutions of gold, containing oxine, showing a pro
nounced pH effect. Coprecipitation was believed to have taken
place over the pH range studies, however no quantitative dat~
could be obtained using Atomic Absorption. Table IX shows the
suppression in absorption signal found for a 0.75 ppm gold stand
ard containing exine as the pH was varied from l to 7. At pH
values above 4.5, where no suppression of signal took place, the
percentage coprecipjjtation was of the order of 70%.
A final phase of this work was to determine if the presence
of an organic carrier precipitate was really necessary for the
recovery of trace amounts of metal chelates from dilute solutions.
Is true coprecipitation taking place, or could any material with
a large surface area serve equally well in retaining the metal
chelates? A suspension of macerated filter paper was passed
through the column apparatus until a tightly packed column of
paper pulp was obtaimed. Three test solutions of cadmium containing
a 1000 fold excess oxine were prepared and adjusted to pH values
of 4.5, 4.75, and .5.0. When these were carried through the
coprecipitation procedure previously described, zero percent
coprecipitation was found for each solution. When 2-naphthol
was used as the column material for the same three solutions,
percentage coprecipitation was 0, 50, and 100 percent respectively.
80
t:l 0
•r-1 .jJ (1j
60 .jJ
•r-1 p,
•r-1 u w l-1 p, 0 u .jJ 40 t:l w u l-1 w ~
20
2 3 4 5 6 7 pH
Figure 6. THE COPRECIPITATION RECOVERY OF SILVER WITH OXINE AND 2-NAPHTHOL
TABLE IX.
THE RELATIVE PERCENT ABSORPTION OF STANDARD SOLUTIONS OF GOLD AS A FUNCTION OF pH
pH
1
2
3
4
5
6
7
0.75 ppm gold standard
oxine - 1 mg./ml.
Relative Percent Absorption no oxine with oxine
16.5 16.5
16.5 12.0
16.5 4.6
16.5 9.6
16.5 16.5
16.5 16.5
16.5 16.5
39
V. CONCLUSIONS
Extensive research has be~n carried out on the ooprecipitation
of trace amounts of metals by precipitating an organic carrier
coprecipitant from an alcoholic solution in the presence of an
aqueous solution of trace metals and chelating agent (4,30,37).
The presence of a metastable liquid phase, formed as the alcoholic
carrier solution is mixed with the aqueous solution, has been
observed and it has been suggested that the microcomponents are
extracted by this transient liquid which in turn is mechanically
trapped by the carrier during precipitation (3?).
The results of this study indicate that the recovery of trace
amounts of metal chelates from very dilute solutions is just as
effective using a ''column" of solid organic material as the usual
procedure of precipitating the carrier from an alcoholic solution.
Preliminary experiments with different physical foxms of the carrier
precipitate indicate adsorption as a possible mechanism in the
column-coprecipitation process. Investigations of the coprecipitation
ability of phenolphthalein and 2-naphthol for copper oxinate,
indicate 2-naphthol to be superior. Further studies with the oxine-
2-naphthol system showed that complete recovery and separation was
possible for the oxinates of copper, cobalt, eadmium, and manganese
by careful adjustment of the pH and excess exine concnetration. The
complete recovery of trace amounts of silver was also shown to be
possible with this system. Further research will doubtless reveal
the applicability of the technique for many other metals.
40
The separation of metals by this method appears to be based
on the difference in stability cQnstants of the metal chelates.
Good qualitative agreement was found between the experimental p~
values for four metal oxinates and their stability constants.
In the past, the quantitative determination of trace elements
in coprecipi~tion studies has been accomplished with emission
spectroscopy, colorimetric methods, or radioaative tracers. Eaeh
of these methods has several d.isadvantages. In the present study
investigations were carried out on the usefulness of a relatively
new analytical method, Atomic Absorption Spectrophotometry, for
determining the extent of coprecipitation. Experiments have shown
the method to be relatively free from interference by some reagents
used in coprecipitation studies. It is a rapid method not requiring
prior chemical separations or extensive sample treatment as w:i.th
colorimetric methods. However its sensitivity limitations are •
disadvantage·; lead and nickel could not be included in the present
work due to poor sensitivity.
In coprecipitation research, it is desirable to study the
behavior of several elements simultaneously. Although Atomic
Absorption has this desirable inherent capability of multielement
anal~sis on the same test solution, advantage could not be taken
of this due to insufficient sensitivity. Determinations had to be
carried out on the elements, singly, because the extra exine
concentration needed to give a high level of excess for several
elemente simultaneously, would precipitate out at the higher pH
values where optimum coprecipi tation occured. This ,oal..d have
been overcome if the concentration of metal ion could have been
41
.owered, thus lowering the concentration of chelating agent required
;o give the desired level of excess. However the concentration of
metal ion could not be lowered since no additional increase in sen
sitivity could be attained.
Work with Atomic Absorption during this study has disclosed a
novel application of the technique for the quantitative uindirect 11
determination of trace amounts of chelating agents. Chelates,
many times, form complexes with metals in aqueous solutions which
can be extracted into immiscible organic solvents. The amount of
metal extracted is controlled by the concentration of the chelating
agent. In this work, it has been observed that if an excess of
metal ion is added to a series of standard solutions of chelating
agent, and the solutions extracted with an organic solvent, a
direct relationship can be observed between the reduction in Atomic
Absorption signal for the metal in the aqueous phase and the con
centration of the chelating agent. The concentration ranges of
the chelating species being determined can readily be extended by
varying the amount of excess metal present.
BIBLIOGRAPHY
1. Dehm, R.L., Dunn, W.G., and Loder, E.R., Anal. Chem. 33 , 607 (1961)
2. Farmer, V.C., Spectrochem. Acta., ~ , 224 (1950)
3. Heggen, G.E., and Strock, L.W., Anal. Chem. 25 9 859 (1953)
4. Kuznetsov, V.I., Zhurn. An~~. Khim. ~, 199 (1954)
5. Ibid., 10 , 32 (1955) - . 6. Kuznetsov, V.I., and Myosoedova, G.V., Zhurn. Anal. Khim.
!Q 9 21$1 (1955)
7. Kuznetsov, V.I., Session of USSR Academy of Sciences on Peaceful Uses of Atomic Energy, Chemical Section, p. 177 (1955)
8 .. Kuznetsov, V.I., and Papaushina, L.I., Zhurn. Anal.., Khim. ll ' 686 (1956)
9. Kuznetsov, V.I., Ibid., 13 9 79 (1958)
42
10. Kuznetsov, V.I .. , and Myosoedova, G.V., Tr. Komia. po Analit. Kbim. Akad. Nauk. SSSR Inst. Geokbim. i A.na1it. Khim.. 2. ' 76 (1958)
11. Ibid., P• 89
12. Kuznetsov, V.I.., and Aki:miva, T.G., Radiokhim. 2 , 357 (1960}
13. Ibid., 2 , 426 (1960)
14. Ibid., l , 737 (1961)
15. Ibid., 4 , 188 (1962)
16. Ibid., l , 93 (1963)
17. Kuznetsov, V .. I., Myosodova, G.V., Akimova, T.G. and Nikolskaya, I.V., Tr. Komia. po Analit. Khim. Akad. Nauk. SSSR Inst. Geokhim. i Analit. Khim. 12 9 296 (1965)
18. Ibid., P• 279
19. Kuznetsov, V.I., Gorshkov, v.v., and Orlova, L.P., Agrokbim. E. t 118 (1964)
20. Kuznetsov, V.I., and Slovera, T.V., Dokl. Akad. Nauk. SSSR 167 ' 1063 (1966)
21. Lai, M.G., and Weiss, H.V., Anal .. Chem. 34 , 1012 (1962)
22 .. Mellor and Maley, Nature 159 9 370 (1947)
43
23. Mitchell, R.L., and Scott, R.O., J. Soc. Chem. Ind. 62, 4 (1943)
24. Ibid., 66 , 330 (1947)
25. Mitchell, R.L., Commonwealth Bureau of Soil Science, Tech. Comm. No. 44, Harpended, England, 1948
26. Mitchell, R.L., and Scott, R.O., Spectrochem. Acta. 2 ,367 (1948)
27. Pickett, E.E., and Hankins, B.E., Anal. Chem. ZQ, 47 (1958)
28. Sandell, E.B., "Colorimetric Determination of Traces of Metals", Chemical Analysis Series, Vol. III., Third Ed., InterscienceoPublishers, Inc., New York (1959)
29. Smit, J. and Smit, J.A., Anal. Chem. ~ , 274 (1953)
30. Tappmeyer, W.P., and Pickett, E.E., Anal. Chem. 34, 1709 (1962)
31. Troitskii, K.V., Zhurn. Neorg. Khim.!, 1104 (1956)
32. Weiss, H.V., and Lai, M.G., Anal. Chem. 32, 475 (1960)
33. Weiss, H.V., and Shipman, W.H., Ibid., 34 , 1010 (1962)
34. Weiss, H. V., Lai, M.G., and Gillespie, A., Anal. Chem. Acta. 2.5 t 550 (1961)
35. Weiss, H. V., and Lai, M.G., Talanta~~ ,72 (1961)
36. Ibid., J. Inorg. Nucl. Chem. 17 t 366 (1961)
37. Williams, J.C., Ph.D. Thesis, University of Missouri (1964)
44
APPENDIX
TABLE X.
INSTRUMENT PARAMETERS
Scale Elements Settings Mn Co Cu Pb Ni Ag Au Cd Zn
Scale Expansion lOX lOX lOX lOX lOX lOX lOX lOX & lX lOX & lX
Meter Response 3 2 3 2 3 2 2 2 2
Slit Selector 2 3 4 4 3 4 5 4 4
Grating Counter 280 241 325 217 232 328 243 229 214
Air Flowmeter 9 9 9 9 9 9 9 9 9
Acetylene Flowmeter 9 9 9 9 9 9. 7.5 9 9
46
80 Mn 2795 & 2798 A Q 0
•.-I .J-J 0.. 1-1 0 Ul 60 ~ -l-1 Q <I) C)
1-1 <I)
P-1
Cl) 40 > •.-I .J-J cU
.--l <I)
~
20
0.2 0.4 0.6 0.8 1.0 Manganese Concentration, ppm
Figure 7 • STANDARD CURVE FOR MANGANESE
(\) C) c: a:s
.a !--1 0 til
~
.20 Co 2407 A
.15
.10
.05
0.2 0.4 0.6 Cobalt Concentration, ppm
Figure 8. STANDARD CURVE FOR COBALT
47
0.8 1.0
48
.08 Cd 2288 A
.06
.04
.02
0.2 0.4 0.6 0.8 1.0 Cadmium Concentration, ppm
Figure 9. STANDARD CURVE FOR CADMIUM
25 Cd 2288 A
Q 20 0 •.-l .u 0.. 1-1 0 Cl)
~ .u Q 15 C) (.)
1-1 C)
t:t< C)
:> ·.-l .u cO
r-1 10 C) p:::
5
.02 .04 .06 .03 Cadmium Concentration, ppm
Figure 10. STANDARD CURVE FOR CADMIUM
50
35 Ni 2320 A
30
r:: 0 25 •.-I l-1 p.. l-1 0 Cl.l
~ l-1 s:: <l) 20 ()
l-1 <l)
P-<
<l)
:> •...t l-1 m
r-1 <l) 15 ~
10
5
2 4 6 8 10 Nickel Concentration, ppm
Figure 11. STANDARD CURVE FOR NICKEL
51
70 Ag 3221 A
60
s:: so 0 •ri -I.J 0.. H 0 C/l
~ -I.J ~
40 (!)
0 H (!)
p.,
(!)
:> •ri -I.J C\1
...-1 30 (!)
0:::
20
10
0.2 0.4 0.6 0.8 1.0 Silver Concentration, ppm
Figure 12. STANDARD CURVE FOR SILVER
52
.12 Pb 2170 A
.10
.08
.06
.04
.02
2 4 6 8 10 Lead Concentration, ppm
Figure 13. STANDARD CURVE FOR LEAD
53
25 Zn 2138 A
Q 20 0 ·~ +J p.. H 0 Ul
,.0 ~
+J Q 15 <lJ (.)
H <lJ p..
<lJ l>
•.-I +J cd
.....-! 10 (!)
~
5
.02 .04 .06 .08 0.1 Zinc Concentration, ppm
Figure 14. STANDARD CURVE FOR ZINC
54
40 Cu 3247 A
l::l 0
•.-I .u 0, l-1 0
30 UJ ,.0 <! .u l::l (!) (.)
l-1 (!)
P-1
(!)
> 20
·rl .jJ
<d r-l (!) p::
10
0.1 0.2 0.3 0.4 0.5 Copper Concentration, ppm
Figure 15. STANDARD CURVE FOR COPPER
55
40
c: 0
•.-l .j.J
0... 1-1 0
30 Iii) ,..a < .j.J
c: Q)
0 1-1 Q)
P.r
Q) 20 >
•.-I .j.J
til ~ Q) p::
10
"'
0.6 1.2 1.8 Gold Concentration ppm
Figure 16. STANDARD CURVE FOR GOLD
ACKNOWLEDGMENTS
The author would like to take this opportunity to thank
his advisor, Dr. Wilbur P. Tappmeyer, for his suggestions and
guidance during the course of th~s study.
Thanks also goes to Dr. Ernst A. Bolter of the Geology
Department for permission to use their Atomic Absorption
instrument.
For their continuous encouragement and support throughout
his educational career, the author gratefully acknowledges his
parents, Mr. and Mrs. Paul R. Schucker.
56
57
VITA
The author was born in McConnellstown, Pennsylvania on
October 29, 1936. He was graduated from Huntingdon High School
in June 1954. In September of 1954 he entered Juniata College,
Huntingdon, Pa. and was graduated in 1958 with a B.S. in Chemistry.
During the years 1958-1962 he was employed as a chemist by
the Pennsylvania Railroad Company Test Department, Altoona, Pa.
From 1962-1965 he worked in the Materials Science Center of
Cornell University, Ithaca, N.Y. He began graduate study at the
University of Missouri at Rolla, Rolla, Mo. in September of 1965.
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