Determinação dos compostos orgânicos voláteis (COVs) do bio-óleo de pirólise rápida por headspace CG-DIC

Abstract

The current growing of bio-oil interest for power generation and production of chemical inputs does the bio-oil from the fast pyrolysis of biomass an interesting raw material for chemical compounds of great value. The volatile organic compounds (VOCs) of bio-oil as methanol, ethanol, acetone, acetic acid and furfural can be recovered and marketed. The determination and quantification of VOCs are performed by gas chromatography, but VOCs bio-oil cannot be characterized directly by gas chromatography, as the bio-oil is a complex matrix, and requires several sample preparation steps. This problem can be solved by full evaporation headspace (HS/FE) and gas chromatography (GC) analysis. This paper presents a simple and rapid method to characterize methanol, ethanol, acetone, acetic acid and furfural in samples of bio-oil by HS/FE-GC. The method uses 4 µL sample of bio-oil in a headspace vial (22 mL), the time for complete evaporation of the compounds was 7 minutes at 90 °C, and detection and quantification was performed by a flame ionization detector using external analytical curves. The results showed that the method can be applied for determining VOCs of bio-oil, detection limits ranged from 0.13 to 0.16 µg of the compounds. The method showed excellent accuracy with the following recoveries: methanol (100.9%), ethanol (99.2%), acetone (92.8%) and acetic acid (104.3%). Furfural recovery was low, about 74.3% and it was associated to polymerization with phenolic the compound of bio-oil. The major volatile organic compound was acetic acid with 11.13%, followed by methanol with 0.39%, 0.26% ethanol, 0.04% acetone and 0.01% furfural.