Decolorization of Raw Cane Sugar Syrup by using Activated Carbon Made from Sugarcane Bagasse
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Date
2019-06
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Addis Ababa University
Abstract
Activated carbon is used in sugar industries for the removal of colorants from sugar liquor. It is also
used for treatment of potable water as well as industrial wastewater. Coal is a commercially used
activated carbon, which is a limited non-renewable resource. However, there are different renewable
resources such as sugarcane bagasse, peanut shells, rice husk, rice straw, coconut shells, which could
be used as alternatives. The aims of this study were to decolorize raw cane sugar by using activated
carbons prepared from renewable low cost sugarcane bagasse (SCB) and to investigate the effects of
reagent to precursor ratio and activation temperature on decolorization efficiency. SCB was ground
to the desired particle size, screened and characterized for powdered activated carbons (PAC)
preparation. Sodium hydroxide (NaOH) at 0.25:1.0 and 0.5:1.0 impregnation ratio (IR-reagent to
precursor) was used as an activating agent. The carbons were prepared in a carbonization process in
an inert environment with a nitrogen gas flow rate of 0.2 l/min at temperatures of 500°C and 600°C
for three hours. Using the same temperature and activation time but without reagent, bio-chars were
also prepared for control and reference purpose to compare and contrast effects of reagent on
prepared carbons properties and adsorption efficiency. The prepared carbons were characterized for
their proximate and surface properties. Carbon yield, amount of burn off and bulk density were also
determined for each sample of prepared carbons. Decolorization efficiency of each carbon was batch
tested using ICUMSA method. The effects of carbon dose, raw sugar solution (syrup) concentration,
solution temperature, and adsorption time on decolorization efficiency were studied in this
experiment. The adsorbent prepared at a temperature of 600°C and 0.5:1.0 IR gave the best quality
with respect to carbon yield (25.5204 %), bulk density (0.4022g/ml) and decolorization efficiency
(56 %). The second best quality adsorbent, in terms of these parameters, was the carbon prepared at
5000C with the same IR having the results of 29.9081 %, 0.4028 g/ml and 40 % respectively.
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Keywords
Activated carbon, Raw sugar syrup decolorization, Sugarcane bagasse