Low temperature conversion of sugar-cane by-products

Abstract

This work reports the low temperature conversion (LTC) of the most important sugar-cane by-products, i.e., sugar-cane bagasse, filter mud, molasses and alcohol sludge, into oil, char, reaction water and non-condensable gases. The oil was analysed for fatty acids and hydrocarbons. Active carbon was produced from the char and was characterized subsequently. Filter mud gave the highest yield of LTC oil (20.6%), while other samples recorded yields lower than 6%. The heating values of the oils were between 24.5 kJ g −1 and 35.6 kJ g −1. Thermogravimetric studies of the LTC oil from filter mud indicated that 99% was vapourized at temperatures below 450°C. Varying concentrations of C 8–C 30 hydrocarbons were detected in the oil. The distribution pattern of hydrocarbons, however, was unusual compared to typical oils from LTC. The yields of LTC chars were between 35.4% and 77.6%. These chars have been activated and the conditions were optimized. Active carbon from bagasse recorded a high iodine and methylene blue number (1180 mg g −1 and 275 mg g −1 respectively). The BET surface is also very high (1035 m 2 g −1) and consists of a large proportion of micro- and mesopores. Active carbons produced from the other samples however exhibited also fairly high iodine, methylene blue and BET values. These results are discussed comparatively and the potential of the wastes is outlined.