Higher heating values of hydrotropic, hidrolytic and alkaline lignin from grape seeds and other types of biomass

Abstract

Lignin is a natural polymer aromatic-based that exhibit interesting application both as a final product and as a source of energy and aromatic compounds. For decades lignin has been a discarded sub product of the pulp industry (black liquor) used basically as energy source for the pulp mill, creating a number of environmental problems. Currently a number of production processes are available, i.e. alkaline extraction, Kraft, organosolv, hydrotrope extraction, hydrolysis in sub and supercritical water, for instance. The Higher Heating Value (HHV) is a required parameter for the characterization of the biomass fractions. There are techniques to estimate HHV using the elemental composition and other parameters, but this is an indirect method and requires the availability of the analytical techniques. In this work we determine the HHV of three types of lignin, alkaline (19.82 kJ/g), hydrotropic (26.54 kJ/g) and from subcritical water hydrolysis (26.19 kJ/g), also cellulose (16.31 kJ/g), anhydrous glucose (15.64 kJ/g), grape seeds (18.84 kJ/g) and extracted grape seeds (23.78 kJ/g) by using an adiabatic combustion calorimeter and a combustion bomb. We propose the use of cellulose as agglomeration agent for the biomass and lignin, simplifying the pellet preparation process. Calibrations repeatability for a standard of Benzoic Acid was 1.9% and for a standard of Anhydrous Glucose was 3.4%. Finally, the average from calibrations was 2.6%.