The feasibility of an activated charcoal/ultrafiltration process for the decolouration of beet molasses, and
subsequent regeneration of the exhausted charcoal by thermal and chemical methods, has been examined.
Several activated charcoals were assayed prior to the selection of Norit powdered activated charcoal
(NPAC). The affinity of NPAC for the adsorption of dark colour compounds was studied at 25 C. A colour
reduction of over 98% was achieved at equilibrium using an NPAC concentration of 5 g/L from the beet
molasses at pH 3, with no betaine or sucrose co-adsorptions. Crossflow ultrafiltration experiments with
NPAC were performed using a 100 kDa TiO2 tubular ceramic membrane, in order to select the optimal
operating conditions. Experiments with several ultrafiltration stages for the decolouration of beet
molasses, and subsequent regeneration of the exhausted NPAC with sodium hydroxide solutions, were
also performed under the conditions identified previously. A high colour reduction in the molasses of
over 96.5%, with no adsorption of sucrose, betaine, citric acid or lactic acid, was achieved in the first
decolouration stage at pH 3, with an initial NPAC concentration of 5 g/L, a transmembrane pressure of
100 kPa and a feed flowrate of 4.24 L/h. A good NPAC regeneration was obtained, with a loss of its colour
removal capacity lower than 10%.
