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4.1 Basic Principles of Adsorption and Ion Exchange 257

However, there also some disadv the limited radiation and thermal , ically antages. Specif
stability set limits to the usage of synthetic organic ion-exchange resins. Regarding tem-
perature, 150 °C is the maximum temperature that cation-exchange resins can withstand,
,
whereas 70 °C is the limit for anion-exchange resins. Consequently hot streams to be
v treated hae to be cooled below these temperatures.
In Tables 4.9 and 4.10, a comparison of organic and inorganic ion exchangers is pre-
sented.

Classification based on matrix
Polystyrene divinylbenzene: Ion-exchange resins are commonly manufactured from a
copolymer of styrene (Figure 4.8) and diylbenzene (Figure 4.9). The di vin ylbenzene vin
content in the matrix determines the degree of cross-linking. So, 5% mol di ylbenzene vin

Table 4.9
Qualitative comparison of organic and inorganic ion e xchangers
Property Organic exchangers Inorganic exchangers

Chemical stability Good Fair to good
Thermal stability Fair to poor Good
Mechanical strength Good Variable
Exchange capacity High Variable
Regeneration Good Limitedre generation
performance
Immobilization Good; Good;
imobilized in a v ariety converted into
of matrixes or can be equivalent mineral
incinerated structures
Cost Medium to high Low to high

Table 4.10
Quantitative comparison of organic and inorganic cation e xchangers
Exhanger Capacity
(kg/ft 3 )
Natural zeolites 3–5
Synthetic zeolites 12–16
Organic
Sulfonated coal (carbonaceous) 5–7
Organic 6–18
Synthetic
Phenolic
Organic 20–30
Synthetic
Styrene base
Organic synthetic resins 10–22