Ion-exchange resin

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Ion-exchange resin

An ion-exchange resin or ion-exchange polymer is an insoluble matrix (or support structure) normally in the form of small (1–2 mm diameter) beads, usually white or yellowish, fabricated from an organic polymer substrate. The material has a highly developed structure of pores on the surface of which are sites with easily trapped and released ions. The trapping of ions takes place only with simultaneous releasing of other ions; thus the process is called ion-exchange. There are multiple different types of ion-exchange resin which are fabricated to selectively prefer one or several different types of ions.

Ion-exchange resins are widely used in different separation, purification, and decontamination processes. The most common examples are water softening and water purification. In many cases ion-exchange resins were introduced in such processes as a more flexible alternative to the use of natural or artificial zeolites.

Most typical ion-exchange resins are based on crosslinked polystyrene. The required active groups can be introduced after polymerization, or substituted monomers can be used. For example, the crosslinking is often achieved by adding 0.5-25% of divinylbenzene to styrene at the polymerization process. Non-crosslinked polymers are used only rarely because they are less stable. Crosslinking decreases ion-exchange capacity of the resin and prolongs the time needed to accomplish the ion exchange processes. Particle size also influences the resin parameters; smaller particles have larger outer surface, but cause larger head loss in the column processes.

Uses

Water softening

In this application, ion-exchange resins are used to replace the magnesium and calcium ions found in hard water with sodium ions. When the resin is fresh, it contains sodium ions at its active sites. When in contact with a solution containing magnesium and calcium ions (but a low concentration of sodium ions), the magnesium and calcium ions preferentially migrate out of solution to the active sites on the resin, being replaced in solution by sodium ions. This process reaches equilibrium with a much lower concentration of magnesium and calcium ions in solution than was started with.

The resin can be recharged by washing it with a solution containing a high concentration of sodium ions (e.g. it has large amounts of common salt (NaCl) dissolved in it). The calcium and magnesium ions migrate off the resin, being replaced by sodium ions from the solution until a new equilibrium is reached. The salt is used to recharge an ion-exchange resin which itself is used to soften the water.

Water purification

In this application, ion-exchange resins are used to remove poisonous (e.g. copper) and heavy metal (e.g. lead or cadmium) ions from solution, replacing them with more innocuous ions, such as sodium and potassium.

Few ion-exchange resins remove chlorine or organic contaminants from water – this is usually done by using an activated charcoal filter mixed in with the resin. There are some ion-exchange resins that do remove organic ions, such as MIEX (magnetic ion-exchange) resins. Domestic water purification resin is not usually recharged – the resin is discarded when it can no longer be used.

Production of high purity water

Water of highest purity is required for electronics, scientific experiments, production of superconductors, and nuclear industry, among others. Such water is produced using ion-exchange processes or combinations of membrane and ion-exchange methods. Cations are replaced with hydrogen ions using cation-exchange resins; anions are replaced with hydroxyls using anion-exchange resins. The hydrogen ions and hydroxyls recombine producing water molecules. Thus, no ions remain in the produced water. The purification process is usually performed in several steps with "mixed bed ion-exchange columns" at the end of the technological chain.

Juice purification

Ion-exchange resins are used in the manufacture of fruit juices such as orange and cranberry juice where they are used to remove bitter tasting components and so improve the flavor. This allows tart or poorer tasting fruit sources to be used for juice production.

Sugar manufacturing

Ion-exchange resins are used in the manufacturing of sugar from various sources. They are used to help convert one type of sugar into another type of sugar, and to decolorize and purify sugar syrups.

From Wikipedia, the free encyclopedia

 



 URELY

Bayer

Mitsubishi
Diaion

Dow
Dowex

Purolite

ResinTech

Rohm&Haas

Sybron

Amberlite

Duolite

Cation Exchange Resins

001x7

S100LF


HCR-S(E)S

C100E


SR1L



001x7
H




C100H





001x8

S100

SK1B

HCR-S(E)

C100

CG-8

IR-120

C-20

C-249

001x10

S110

SK110

HGR-W2/C10

C100X10

CG-10

IR-122

C-20X10

C-250

001x16


SK116







SQ-66




SST-60





SQ-68








C-249NS

D001

SP112

PK216

MSC-1

C150

SAC MP

Amb 252

C-26S

CFP-110

SQD-65

SP120

PK228

CM15/16

C160




C-360

SQD-67




C160





D113-III

CNP-80

WK-40

MWC-1

C104E

WAC MP

IRC-76/84


CCP

SQD-85

CNP/LF

WK-20

MAC-3

C107E





SQD-88


WT01S


C115E


IRC-50



Anion Exchange Resins

201x4

M504/510

SA 12A

SBR-P

A400

SBG 1P

IRA402/420

A-113

ASB-1P

201x7

M500/511

SA 10A

SBR

A600

SBG 1

IRA400

A-109

ASB-1

202-II

M600/610

SA 20A

SAR

A200/300

SBG 2

IRA410

A102/104

ASB-2

D201

MP500

PA308/312

MSA-1

A500

SBMP 1

IRA900

A-161

A641

D202-II

MP600

PA412/416

MSA-2

A510


IRA910

A-162

A651

D296

MP500A




SBG-1VP

IRA901/904


A642

DOC2001

S6328A

HPA25


A500P

SIR-22P

IRA958



D208



1X1






D301-III

MP62


66

A100


IRA94

A-329S


D301-G

MP64

WA 30

MWA-1

A100E

WBMP

IRA93/95/96



213

VP OC1071



A850E

SBACR1

IRA458


A475

D218

VP OC1074



A860


IRA958


MACRO-T

313

VP OC1072

WA 11


A845/847


IRA67



D318

AP49



A830


IRA68


A375

D818

AP49



A830




A375
















 


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