Decolorization of molasses' wastewater using activated carbon prepared from cane bagasse

The decolorization of synthetic melanoidin was studied using activated carbon from cane bagasse obtained from Thailand and Brazil. Melanoidin, a nitrogenous brown polymer present in molasses' wastewater, is formed on the interaction between amino acids and carbohydrates. Bagasse, another by-product in the sugar industry, is a cheap material suitable for the preparation of activated carbon. Samples of cane bagasse were carbonized using nitrogen gas at 300 degrees C and activated with steam at 800 degrees C in a ceramic boat inside a horizontal electric furnace consisting of a batch reactor. Yields were determined and values of 10-20% were obtained. Proximate analyses show that the bagasse samples appear to be adequate precursors for activated carbon because of their low ash content. The activated carbons were characterized for their adsorptive capacities on melanoidin. Results showed that the activated carbons have high adsorptive capacities that favorably compare well with a commercial activated carbon. BET surface areas were determined using nitrogen gas for adsorption and results showed surface areas greater than 400 m(2) g(-1), the value for most commercial activated carbons. The activated carbons produced are therefore comparable commercial ones. Regeneration of the spent carbon showed an increase in the adsorptive capacity and yield. (C) 1997 Elsevier Science Ltd.