Modeling adsorption of cane-sugar solution colorant in packed-bed ion exchangers

• Published in: AIChE journal Vol. 49; no. 10; pp. 2519 - 2532
• Main Authors: Broadhurst, Hugh A., Rein, Peter W.
• Format: Journal Article
• Language: English
• Published: Hoboken Wiley Subscription Services, Inc., A Wiley Company 01.10.2003; Wiley Subscription Services; American Institute of Chemical Engineers
• Subjects: Biological and medical sciences; Food industries; Fundamental and applied biological sciences. Psychology; Sugar industries
• ISSN: 0001-1541; 1547-5905
• DOI: 10.1002/aic.690491008

The removal of cane‐sugar solution colorant by packed‐bed ion exchangers was modeled using a linear driving‐force adsorption model. Adsorption of colorant is a complex subject, since color is an indiscrete mixture of many components, making it difficult to measure and even more challenging to model. Three resins were investigated: a strong‐acid cation (SAC), a weak‐base anion (WBA), and a standard sugar industry strong‐base anion decolorizing resin. Batch testing of the resins produced linear isotherms, indicating that the colorant is dilute. Results from column testing showed that a plug‐flow model with a constant linear isotherm was sufficient in all cases except the SAC resin. The SAC adsorption parameter decreased sharply as the pH increased, causing the colorant to be desorbed from the resin. This situation must be avoided if optimal decolorization is to be achieved.