Decolorization of melanoidin by activated carbon obtained from bagasse bottom ash

A synthetic melanoidin is used as a model for the colorant in sugar syrup to study the mechanism of adsorption on activated carbon (AC) obtained from bagasse bottom ash (BBA). The equilibrium adsorption capacities, fitted with Langmuir and Freundlich models increased with increasing temperatures. Thermodynamic parameters for BBA–AC indicate that the adsorption process is endothermic and spontaneous. No new peaks or no peak shifts were observed in IR spectra as a result of adsorption of the melanoidin on BBA–AC. This indicates a physical adsorption mechanism, which was confirmed by the fact that the melanoidin could be completely desorbed by distilled water. Overall, 8.3 kg BBA–AC was able to reduce melanoidin concentration from 100 mg l−1 to ⩽10 mg l−1 in 1 m3 effluent.