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DOWEX
Ion Exchange Resins
Powerful Chemical
Processing Tools
Table of Contents
Introduction to Ion Exchange Resins . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .2 Applications - Ion Exchange Resins in Chemical Processing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .4 General Considerations for Use of Ion Exchange Resins . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .4 Resins as Solid Acid/Base Catalysts . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .4 Metal Recovery and/or Concentration . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .5 Solution Purification . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .6 Chemical Conversions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .7 Fractionations/Separations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .7 Resins as Desiccants . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .7 Laboratory - Evaluation Considerations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .8 Applications and Recommended DOWEX resins . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .9 Notes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .10 Introduction
DOWEX Ion Exchange Resins -
The Functional Group. Following
Powerful Chemical Processing
ing the flexibility of porosity control.
necessary in this area of processing.
alities that allowed the companiondevelopment of new processes utiliz- Standard DOWEX Ion Exchange Beads
ing these ion exchange related prod-ucts. Processes such as IonRetardation, Ion Exclusion, AcidRetardation, Desiccation, RadiumRemoval, Chelation, and Catalysishave been pioneered by The DowChemical Company, and Dowremains committed to the continuingsupport of this diverse industry.
Important Chemical and Physical
Nature of Ion Exchange Resins
The Matrix. The majority of the ion
exchange resins manufactured in the
world today are based on the poly-
mer chemistry of styrene, crosslinked
with divinylbenzene. The variety of
copolymers and their functionalized
products, available both conceptually
DOWEX MONOSPHERE Ion Exchange Beads
and commercially, are many. Thispolymer system has also stood thetest of time as the most stable sys-tem, physically and chemically, ofany commercially available to date.
nificantly varied by changing theamount of divinylbenzene crosslink-ing agent, which alters the swollengel porosity of the finished ionexchange resin. Reaction rates arethus variable and controllable, as arethe size range of molecules that maydiffuse into and out of the resinstructure. True porosity can also bebuilt into the matrix during the orig- DOWEX Resins Significant to
Type I Strong Base Resins
Chemical Processing
Applications
different selectivity characteristicsresulting in enhanced iron rejection Strong Acid Resins. As produced,
these resins contain exchangeableH+ cations which give the resins the Polymeric Adsorbents. Polymeric
CH3 – N+ – CH3
rials and excellent physical stability.
solution, effectively “salt splitting” and Type II Strong Base Resins
Ion Retardation Resins. Made by
CH3 – N+ – CH2– CH2OH
unique ability to absorb ion pairs (ofsalts) from solution, retarding their Weak Base Resins. These resins
Strong Acid Resins
remove salt contamination from caustic solution.
Styrene-DVB Copolymers. Dow
Weak Base Resins
Styrene-DVB copolymers are freeflowing, spherical beads made from Strong Base Resins. These
CH3 – N – CH3
Weak Acid Resins. These resins
decolorization and precision fillers.
in improved regeneration efficiency.
Chelating Resins. Special function-
Applications - Ion Exchange Resins In Chemical Processing
General Considerations for Use
of Ion Exchange Resins
Aqueous Solutions. Ion Exchange
Resins as Solid Acid/Base
Catalysts
Strong Acid Resins are used in a
catalysts in place of soluble acids.
tion is 0.002 equivalents per liter.
effectively used in phenol alkylation.
Strong Base Resins can replace
Organic Solutions. In general,
Advantages. DOWEX ion exchange
better the chance for ion exchangereactions to occur. Ethanol andmethanol support ionization reason-ably well.
Figure 1. Catalytic Reaction - MTBE Production
oxidizing agents, should be avoided.
These materials can attack the resinand perhaps even cause a haz- Stability Considerations.
which resin degradation occurs. Thestrong base resin in hydroxide formmay be used as base catalysts at Metal Recovery and/or
Concentration
Cobalt/Nickel Recovery and
Separation. For more than a
Uranium Recovery. Of the many
Chromate Recovery. Chromic acid
is suitable for recycle in the process.
Copper Recovery Using Chelating
Resins. Chelating resins are
Precious Metal Recovery. In the
complexes with cyanides or chlorides.
Solution Purification
Figure 2. Iron Removal from Concentrated HCI
Complex mixtures of acids, alkalis orsalts can be purified using ion Iron Removal from Hydrochloric
(Muriatic) Acid. Hydrochloric acid
used in steel pickling baths becomes
contaminated with iron. To maintain
the effectiveness of the bath, iron
contamination must be maintained at
a low level. The strong base resin,
DOWEX MSA-1, has a high affinity
which the resin has for the anioniciron complex decreases, as the HClconcentration decreases, facilitatingthe stripping of iron from the resinwith a water wash. The wash wateris pH adjusted to keep trivalent ironin solution in the effluent strip solu-tion. Figure 2 shows this operation Nitrate Removal from Water.
Nitrate levels in water must be kept
low to meet public health standards.
out using sodium chloride solutions.
selectively, long runs are obtained.
Formic Acid Removal from
Phenol Removal from Aqueous
Formaldehyde Solution. Formic
Solution. Phenol contamination
Aluminum Removal from
Phosphoric Acid Bright Dip Bath.
Radium Removal from Water.
Chemical Conversions
Iron Removal from Phosphoric
Acid Pickling Solution. Steel pick-
Silica Sol Production from Sodium
Silicate. In the production of silica
Reactivation Considerations.
Resins as Desiccants
Ideal for Non-polar Solvents.
terminals around the country bypassing through beds of DOWEX Fractionations/Separations
A number of ion exchange process-es are chromatographic in nature.
Figure 3. Ion Retardation Separation of NaOH & NaCI
Acid Retardation Separation of
Sulfuric Acid from Salts. Mixtures
of sulfuric acid and its salts are sep-arated by passage through a bed of acid is the imbibed species, separa-tion from large organic salts is also Ion Exclusion Separation of
Glycerin from Salts. Using similar
chromatographic operating tech-
niques, glycerin has been separatedfrom salts by passing the solution salt is excluded by Donnan mem-brane exclusion effects.
Ion Retardation Separation of
Salts from Caustic. Caustic solu-
tions (NaOH, KOH, etc.) are contam-
inated with various levels of chloride
salts in some production processes
and in some uses. These materials
can be substantially freed of the salt
contamination by treating a caustic
solution through a specific DOWEX
Laboratory - Evaluation Considerations
Batch Operation. Occasionally, the
see “Equilibrium Isotherm Testing”.
a desired separation. In thisapproach, equilibrium adsorption Consider DOWEX Ion Exchange
Resins for your Application
Column Operation. Ion exchange
generally fixed at about 3 feet. Theadditional column depth is to allow solutions being processed. Also, insome applications resins may swellsignificantly and care must be takento avoid column breakage. (NOTE:Resin expansion requires that col-umn configuration be such that thevolume change can occur vertically.
Tall, narrow columns might restrainthis expansion and cause strong lateral pressures to develop in the column, resulting in resin beingcrushed, or in a column being ruptured).
Applications and Recommended DOWEX Resins
Catalysis
Desiccation
Solution Purification
Trivalent Chromium Removal from Chromate Solutions Copper and Vanadium Recovery from Adipic Acid Manufacture Metal Recovery And/Or Concentration
DOWEX SBP-P; DOWEX M 41;DOWEX OPTIPORE L285 OR L493 Fractionation/Separation
Styrene-DVB Copolymers
For lubrication, void space maintainers, grinding media, absorption and decolorization and precision fillers.
Other grades and sizes can be manufactured upon request Polymeric Adsorbents
For Liquid Applications
For Vapor Applications
Dow Liquid Separations Offices.
For more information call Dow Liquid Separations:
Dow Europe
Dow Pacific
Dow North America
Dow Latin America
Internet
Dow Pacific
† Toll-free telephone number for the following countries: Austria, Belgium, Denmark, Finland, France, Germany, Hungary, Ireland, Italy, The Netherlands,Norway, Portugal, Spain, Sweden, Switzerland, and the United Kingdom Warning: Oxidizing agents such as nitric acid attack organic ion exchange resins under certain conditions. This could lead to anything from
slight resin degradation to a violent exothermic reaction (explosion). Before using strong oxidizing agents, consult sources knowledgeable in
handling such materials.
Notice: No freedom from any patent owned by Seller or others is to be inferred. Because use conditions and applicable laws may differ
from one location to another and may change with time, Customer is responsible for determining whether products and the information in this
document are appropriate for Customer’s use and for ensuring that Customer’s workplace and disposal practices are in compliance
with applicable laws and other governmental enactments. Seller assumes no obligation or liability for the information in this document. NO
WARRANTIES ARE GIVEN; ALL IMPLIED WARRANTIES OF MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE ARE
EXPRESSLY EXCLUDED.

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