Pyrolysis of aquatic fern and macroalgae biomass into bio-oil: Comparison and optimization of operational parameters using response surface methodology

Abstract

Effect of temperature (300–500 °C), carrier gas flow rate (0.2–0.8 L min−1), and the heating rate (10–20 °C min−1) on the final bio-oil production from the Salvinia auriculata (SA) and Ulva lactuca (UL) was optimized using response surface methodology (RSM), established by a central composite design (CCD). The maximum bio-oil yield from UL was 34.8%, reached at 500 °C, 0.2 L min−1 nitrogen flow rate, and 10 °C min−1 heating rate. However, in the case of SA feedstock, the highest bio-oil yield was 32.3% at 400 °C, 0.5 L min−1 nitrogen flow rate, and 20 °C min−1 heating rate. Both bio-oil samples contained saturated and unsaturated hydrocarbons; but the average hydrocarbon chain length in UL bio-oil (C4–C16) was relatively shorter than bio-oil from SA (C6– C24). The bio-oil from A. filiculoides exhibited higher HHV values than that of UL derived bio-oil due to its relative large carbon and hydrogen concentration and small oxygen content. Although both the bio-oils showed different heating values, the UL biooil had more appropriate properties, i.e. lower viscosity and density.