DECOLORIZATION AND CHEMICAL REGENERATION OF GRANULAR ACTIVATED CARBON USED IN CITRIC ACID REFINING

Abstract

Citric acid fermentation (CAF) liquor decolorization by granular activated carbon (GAC) was studied and an improved chemical regeneration method of the exhausted GAC by the color of CAF liquor was investigated. The effects of the GAC dosage, time and temperature on the decoloring efficiency (DE %) were studied. The DE % of the original GAC was 91 %. The regeneration efficiency (RE %) using chemical regents was 104 % of the original GAC. Hot water as cheap reagent was found to be much helpful to the regeneration efficiency. Using oxidant and surfactant in addition to just using NaOH solution can recover 10 % more adsorption capacity of renewed GAC. The adding dosage of oxidant is good at 3 % of exhausted GAC weight; that of surfactant is good at 0.1 %. Comparing with steam regeneration method, high regeneration yield (> 95 %) of chemical method was an attractive economic factor. The results of this investigation can be as helpful reference for citric acid manufacturer expanding profits.

KEY WORDS: Granular activated carbon, Decoloration, Chemical regeneration, Citric acid fermentation liquor


Bull. Chem. Soc. Ethiop. 2009, 23(1), 29-36.