Characterization and antioxidant properties of ethyl acetate fractions from pyroligneous acid obtained by slow pyrolysis of palm kernel shell

Abstract

Sustainable and renewable utilization of Palm kernel shell biomass, can be achieved by thermochemical conversion method of slow pyrolysis which is simple, cost effective and eco-friendly. Palm kernel shell biomass has unlimited potential, as an alternative form of fossil fuels and source of value added chemicals. The refined bio-oil termed Pyroligneous Acid (PA) has been found to contain phenolic and antioxidant activity. These compounds have various applications. However, the low concentration of the antioxidant phenols makes producing chemicals and medicines from palm kernel shell less viable. A higher yield percentage can be obtained from fractionation which also simplifies identification of compounds. The total phenolic contents and antioxidant activities are determined by the Folin ciocalteau and (DPPH and FRAP) assay, column chromatography is used to separate the Pyroligneous acid sample into different fractions, characterization of chemical constituents of the fractions with phenolic activities is carried out by GC-MS. Optimum pyrolysis condition achieved at 429°C residence time 39 o Min -1 with a 40.44 % wt. yield. The obtained results show the presence of phenolic activity in different fractions, the fraction with the highest phenolic activity Fraction 9 (181.75 µg/ml ± 17.0), Fraction 21-25(174.95 µg/ml ± 0.39) and 26-30 (181.76 µg/ml ± 15.54) simultaneously exhibiting high antioxidant activity DPPH Fraction 9 (23.97%), Fraction 21-25(31.39%) and Fraction 26-30 (52.58%). Sixteen different types of phenolic chemical compounds and their derivatives were also identified with up to 60% higher concentrations when compared to previous studies without fractionation. This allows for more economical utilization of viable, pure natural alternatives for producing chemicals and medicines, while simultaneously reducing agricultural waste. Keywords : Palm kernel shell, Slow Pyrolysis, Pyroligneous acid, Antioxidants, Fractionation and GCMS