Optimization of bio-oil production from microwave-assisted pyrolysis of spirulina platensis residue over Fe₃O₄ catalyst

Currently, there has been large interest to utilize biomass as a renewable energy source. Pyrolysis is a part of thermoconversion method to convert biomass to liquid fuel. Here, we have investigated optimization of bio oil production from Spirulina Platensis Residue (SPR) using microwave-assisted pyrolysis with the aid of Fe₃O₄ catalyst and carbon as absorber. Optimization process was conducted using Response Surface Methodology (RSM) with Box-Behnken Design. For this purpose, we have conducted variation of temperatures (500; 550; and 600 °C), catalyst amount (2.5; 5; and 7.5 grams), and biomass particle sizes (50; 100; and 150 mesh). The pyrolysis reaction was carried out in a 100 ml round flask for 1.5 hours with the addition of nitrogen gas at a flow rate of 1.5 LPM. Our results showed that temperature and catalyst amount significantly influence the yield of bio oil. The proposes empirical model could capture the experimental data well (R2=0.99). The model predicted that the maximum yield of bio oil was obtained at temperature of 553.53 °C with a catalyst amount of 6.338 grams and particle size of 102 mesh which will give maximum yield of 43.5062%. From our experimental data, the maximum bio-oil yield of 43.541% was achieved at centre points which is in close agreement with model prediction. The resulting bio oil consists of 2 phases, the GC-MS analysis of bottom phase of bio oil revealed that the bio oil contains more than 100 components, with the largest component is phenol.