Investigations in the Preparation of a Low-Cost, High-Capacity Ion Exchange Material

81 Pages·02.45 MB·English

by  McGarry, Phillip E

INVESTIGATIONS IN THE PREPARATION OF A
LOW-COST, HIGH-CAPACITY
ION EXCHANGE MATERIAL
by
Phillip E. McGarry
A Thesis
Submitted to the Department of Mineral Dressing
in Partial Fulfillment of the
Requirements for the Degree of
Master of Science in Mineral. Dressing Engineering
22750
RY-MONTANA TECH
kJXTE, MONTANA.
MONTANA SCHOOL OF MINES
Butte, Montana
May 23, 1951
UMI Number: EP33368
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TABLE OF CONTENTS
INTRODUCTION 1
THE HISTORY OF ION EXCHANGE 2
The Discovery Period (1819-1905) 2
The Zeolite Period (1906-1930) - 3
The Organic Zeolite Period (1931-1934) 3
The Resin Period 3
THEORY OF ION EXCHANGE EQUILIBRIA 4
Mechanism of Attachment of Ions 4
Ion Exchange Formulae 7
Factors Affecting Ion Exchange Equilibrium 10
CLASSIFICATION MID PREPARATION OF EXCHANGE MATERIALS 14
Classification of Exchange Materials 14
Preparation of Exchange Materials 15
Qualities Desired in an Exchanger 18
ION EXCHANGE OPERATION 20
Exhaustion 20
Elution 20
Regeneration _ __ _ 20
Rinsing 21
EXPERIMENTAL PROCEDURE 21
Column Tests 21
Agitator Tests 26
Multiple Tank Tests 27
ILLUSTRATIONS
Plate 1: Synthesis of a Typical Exchange Resin 16
Plate 2: Schematic Diagram of Column Apparatus 22
Plate 3: Typical Column-exchange Graphs 25
Plate 4: Schematic Diagram of Multiple Tank Apparatus 28
GRAPHS
Fig. 1: Percent Extration of Zinc by Unactivated
Mineral Wool 30
Fig. 2: Exchange Capacity of Unactivated Mineral Wool 31
Fig. 3: Percent Extraction of Zinc by Activated
Mineral ¥ool 32
Fig. 4: Exchange Capacity of Activated Mineral Wool 33
Fig. 5: Percent Extraction of Zinc by Sulfuric Acid-
activated Quartz 35
Fig. 6: Exchange Capacity of Sulfuric Acid-activated
Quartz 36
Fig. 7: Percent Extraction of Zinc by Sulfuric Acid-
activated Quartz 37
Fig. 8: Exchange Capacity of Sulfuric Acid-activated
Quartz 38
Fig. 9: Percent Extraction of Zinc by Sodium Silicate-
activated Quartz 39
Fig. 10: Exchange Capacity of Sodium Silicate-activated
Quartz 40
Fig. 11: Percent Extraction of Zinc by Unactivated
Sawdust _ __ 4.3
Fig. 12: Exchange Capacity of Unactivated Sawdust 44
Fig. 13: Agitation Tests on Unactivated Sawdust 46
Fig. 14-: Agitation Test on Unactivated Resinous
Sawdust 47
Fig. 15: Agitation Tests on Activated Sawdust 48
Fig. 16: Multiple Tank Tests on Acid-activated
Sawdust 51
Fig. 17: Multiple Tank Tests on Acid-activated
Sawdust 52
INTRODUCTION
Recent advances in the field of ion exchange—in particular,
the introduction of higher capacity exchange materials — have
aroused interest in the possibility of the use of ion exchange
in the mineral industry. Although ion exchange processes find
wide use in water treatment and increasing use in industrial
waste recovery, applications in the mineral industry have been
negligible because of the high cost of the exchange materials.
The purpose of this investigation was to test the exchange
properties of some common materials in an effort to produce
a low-cost exchange material of satisfactory capacity.
The uses to which ion exchange may be put in the mineral
industry may be, in a general way, divided as follows:
(1) Recovery of valuable metals from the dilute solutions
of mine, mill, and smelter waste waters.
(2) Purification of mine, mill, and smelter waste waters
to minimize and control stream contamination.
Since stream contamination is not as great a problem in Montana
as it is in more populous regions, the first of these possibil
ities seems the more attractive.
The materials tested were: mineral wool, crushed quartz,
and sawdust. Of the three, sawdust alone offered possibilities
for further investigation.
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THE HISTORY OF ION EXCHANGE
The history of ion exchange has been aptly described by
Nachod -* as being "characterized by its discontinuity of
development". These discontinuities divide the history of
ion excliange into four general periods; namely, the discovery
period, the zeolite period, the organic zeolite period, and
the resin period.
The Discovery Period: (1S19-1905)
Gazzari, in 1819, did perhaps the first vork on ion ex
change when he found that clays would decolorize liquid manure.
He deduced that the clays removed soluble constituents from
manure solutions and later gave them up to growing plants.
20 23
Thompson and Way are given credit for the discovery
of ion exchange in 1850. They discovered that certain soils
would remove potassium and ammonium ions from solution and
return other ions, principally calcium, to the solution in
exchange.
In 1S52 TJay2-' proved that -ohs active substances in the
soils were sodium-aluminum silicates, or the so-called
zeolites.
- 2 -
The Zeolite Period; (1906-1930)
In his work with alumino-silicates, the German chemist
5
Gans first produced a granular exchanger in 1910, and sug
gested its use in water softening. The synthesis and fusion
of zeolites to produce granular materials vith much higher ex
change capacity than natural soils led to a considerable use of
ion exchange in water softening between 1910 and 1930.
The Organic Zeolite Period? (1931-1934.)
The search for higher capacity, acid-resistant materials
for use in ion exchange led, in the period between 1931 and
1934-* to the patenting of a large number of humin-like sub
stances by Borrowman.^ The most successful of these was sul-
12 19
fonated coal. Later Liebknecht and Smit, independently,
obtained other patents on methods of treatment of organic
substances to produce exchange qualities in them.
These developments gave, for the first time, exchange
materials which were sufficiently acid-resistant to be cap
able of hydrogen ion exchange. They were at first called
"organic zeolites", but are more commonly known now as
carbonaceous exchangers.
The Resin Period; (1935-present)
In 1935, Adams and Holmes synthesized the first resin
exchanger by condensation of phenolsulfonic acid with formal
dehyde. These exchangers are extremely acid-resistant and
have a high capacity. The desirable properties of these
- 3 -
exchangers have led to the widespread use of ion exchange in
many fields.
THEORY OF ION EXCHANGE EQUILIBRIA
The theory of ion exchange is, as yet, in the formative
stage. Several divergent theories have been advanced but no
one theory satisfies all of the data. The same situation exists
in consideration of the mechanism of attachment of ions to
exchangers.
Mechanism of Attachment of Ions:
The most prevalent theory of the mechanism of attachment
of ions to the surface of clay mineral particles is that of
the Gouy diffuse double layer. The diffuse double layer is
Q
a more modern concept of the Helmholtz7 double layer. Helm-
holtz assumed that ions of opposite sign -would be adsorbed
to the surface of the solid in separate, rigid, monoionic
layers, while the Gouy diffuse double layer postulates a
rigidly attached layer of ions on the surface and a diffuse
layer of ions of opposite charge in a relatively wide, mobile
layer extending further into the liquid. If the diffuse
layer consists largely of cations, other cations could be
exchanged for the original cations.
A more recent theory of the attachment of ions to clay
mineral particles is that of Jenny. He visualizes the plate-
shaped particles as having ions adsorbed on their surfaces.
- k -
..see ions oscillate because of heat notion and Browniar- move-
r.cr.t and, at times, may be a considerable distance from the
surface. It is possible, therefore, that another ion could
slip in and occupy this oscillation space if it were approx
imately of the same size as the first ion or if it could be
deiorned sufficiently. This theory also recognizes the diffuse
nature of the adsorbed layer of ions, since the amplitude of
oscillation is considered to be the thickness of the adsorbed
10
layer.
The mechanism of attachment of ions to zeolites is consid
ered to be quite different from tliat of ions to clays. Zeo
lites as used in ion exchange are natural or synthetic sodium-
22
or potassium-aluminum silicates. According to Walton, "prac
tically all of the exchange takes place in the interior of the
particles, which have a gel structure". The capacity of such
exchangers, depending as it does on an exchange of ions within
the particle, would be difficult indeed to calculate theoret
ically, since the density of the gel network of fibers should
vary considerably with the method of preparation. Whereas,
with clay minerals it should be possible to determine the
amount of surface available for adsorption by one of the var
ious methods in use in colloid chemistry, with gels there is
no method known for determining space available for adsorp
tion.
Most of the carbonaceous exchangers also have a gel struc-
- 5 -