Hydrochar-derived activated carbon from sugar cane bagasse employing hydrothermal carbonization and steam activation for syrup decolorization

Activated carbon (AC) was produced from sugarcane bagasse using hydrothermal carbonization (HTC) and steam activation for syrup decolorization. The HTC temperature was 180–240 °C over 30–90 min of holding time and the steam activation temperature was 700–900 °C at 1 h. Results showed that dry-basis AC yield was in the range of 10.4–27.1%. The maximum Brunauer–Emmett–Teller (BET) surface area of the product was 390 m2/g. The average pore size of the AC was 2.2 to 2.5 nm with total pore volume of 0.1–0.25 cm3/g. Decolorization tests showed that the AC produced from low-temperature HTC had better decolorization performance with maximum removal rates of 63.4% and 74% in batch-type and fixed-bed, continuous-flow decolorization, respectively. International Commission for Uniform Methods of Sugar Analysis (ICUMSA) unit reduction of the produced AC was about 62%. This study shows that the AC produced can be used for low-cost preliminary syrup decolorization in sugar mills, offering circular utilization of agricultural residues.