Cane Sugar Refining - Purolite

Cane Sugar Refining with Ion Exchange Resins
Table 3 provides a comparison of the 3 different anionic decolorization resins primarily
being used today, macroporous acrylic, macroporous styrenic and gelular styrenic.
Table 3: Properties of Acrylic and Styrenic Strong Base Anion Decolorization Resins
A860S
Acrylic Macroporous
A500PS
Styrenic Macroporous
A420S
Styrenic Gel
Primary Decolorization
Mechanism
Ion Exchange Adsorption Adsorption
Typical Decolorization 50-60% 65-75% 65-75%
Regeneration Efficiency Excellent Good Good
Regenerant 10% NaCl 10% NaCl/0.5% NaOH 10% NaCl/0.5% NaOH
Matrix Aliphatic Aromatic Aromatic
Max Feed Color IU 2500 800 200
Color Loading BV x IU (68 Bx) 35,000 25,000 20,000
Advantages of Ion Exchange Resin Decolorization
Cost: One advantage of ion exchange resins as sugar decolorizers is economy. The costs
are considered to be about half those of traditional granular carbon or bone char methods.
These costs comprise resin and char uses, energy, labor, maintenance, sugar losses and
costs due to greater ash. Water use decreases from 30% to 50% per sugar output. Energy
savings arising from use of resins come mostly from lower hot water requirements, and
lower volumes of sweetwater produced, with consequent reductions in energy needed
for heating and concentration, respectively. As brine is cheap, regeneration cost is low,
so resin decolorization is a low cost alternative to traditional methods such as activated
carbon or bone char.
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Equipment Size: Flow rate is also much greater through resin than alternative materials.
Thus, less bulky apparatus is needed for given liquor flows. Also, shorter retention times
reduce sucrose degradation during decolorization. As regeneration can be performed
inside resin columns, no special handling systems or other equipment for regeneration
are required.
Automation: The resin process is easily automated, and the liquor and adsorbent
are always contained inside a closed vessel, so the process is more hygienic than other
decolorization processes.