Bio-crude and Bio-char Production via Hydrothermal Carbonization of Spontaneously Grown Ricinus Communis

Abstract

In this study, hydrothermal carbonization (HTC) of Ricinus Communis (RC) (seeds and husks) has been carried out at a temperature range of 120-250 °C, 1 h of residence time, and corresponding autogenous water pressures (2-40 bar) to investigate the production of energy-dense solid (hydrochar) and liquid (bio-crude) biofuels. RC, an oilseed and phyto-depurant plant, exhibits high resistance to drought and climatic variations, and abilities to adapt to polluted and low fertility environments. RC, although is originally from tropical Africa, is also widespread and spontaneously grown in the south of Italy and in particular in the Sicilian region. Dried hydrochars were extracted with acetone (7.5 ml/gr), leading to a bio-crude fraction and a solid residue. The results showed that the bio-crude mass yield increased with increasing HTC temperature up to 47.6% at 250 °C. The bio-crude showed no significant changes in higher heating value (HHV) which was of 35.3 MJ/kg on average. The hydrochar mass yield varied between 78 and 63% at 120 and 250 °C, respectively, and the corresponding acetone-extracted hydrochars showed HHVs of 19.47 and 23.72 MJ/kg. Hydrothermal carbonization proved to be an efficient thermochemical treatment for the production of valuable bio-char and energy-dense bio-crude.