Effect of Mn (II) and ozone on pretreatment of sugar cane bagasse in order to produce cellulosic ethanol

Ozone has been shown effective in the pretreatment of bagasse for cellulosic ethanol production. The objective of this work was to verify the effect of the ion Mn (II) in the pre-treatment to enhance the efficiency of ozone. The bagasse was subjected to the flow of ozone for 20 minutes, then kept 2 hours in a solution of MnSO₄ at concentrations of 2.0 x10^-6 and 2.0 x10^-4 mol L^-1. The insoluble fraction was analyzed by FTIR-ATR and the soluble fraction analyzed through quantification of total phenolic compounds (TPC) and Total Reducing Sugars (TRS). The whole process was carried out in triplicate. The FTIR-ATR spectrum of the pre-treated bagasse showed reductions on peak at 3400 cm^-1 and 2921 cm^-1, related to the stretching of the C-H and O-H groups of cellulose and hemicellulose, respectively. The treatment also decreased bands at 1170 cm^-1 corresponding to vibrations C-O-C of hemicellulose and 1143 cm^-1 refering to stretch of group C-O-C of β-(1-4)-glycosidic bonds. Peaks 1600 cm^-1 and 1505 cm^-1 indicate the aromatic ring vibration, and the bands at 1326 cm^-1 and 1276 cm^-1 are derived from the breakdown of guaiacyl and syringyl rings, respectively, which are components of the lignin. The analysis of the levels of TRS and TPC of pre-bagasse showed that the ion Mn (II) become the ozone action more specific to lignin, reducing in approximately 35% cellulose degradation. In conclusion, the ion Mn (II) increases the efficiency of ozone in disruption of the lignocellulosic material.

ACKNOWLEGMENTS: CAPES, CNPq and FAPESP