Response surface methodology–based extraction optimization with application of ZrCl₄ as novel quenching agent for enhancement of bio-oil yield from Jatropha curcas and Chlorella pyrenoidosa

Jatropha curcas and microalga Chlorella pyrenoidosa, two different biofuel feedstocks, are investigated in the present study for optimization of lipid production in the presence of zirconium tetrachloride (ZrCl₄) as a novel quenching agent. Furthermore, the biofixation ability of C. pyrenoidosa for carbon dioxide was also determined in batch experimental studies. Response surface methodology (RSM) was applied for optimization of bio-oil extraction from selected feedstocks by varying the dose of the quenching agent (mg/g), extraction time (h), and temperature (°C). The optimized yield of bio-oil was obtained with 1.41 mg/g quenching agent, 60 °C temperature, and 1.5 h of reaction time. For J. curcas, optimized yield of bio-oil was 43.78% while 32.45% bio-oil yield was obtained with C. pyrenoidosa. Microalga showed highest biomass productivity (289.34 g L⁻¹ day⁻¹) at 10% CO₂ concentration while maximum CO₂ sequestration (5.5 ± 0.07 g CO₂ L⁻¹ day⁻¹) was observed at 20% CO₂ concentrations. Bio-oil obtained from both feedstocks was analyzed by Fourier transform infrared spectroscopy (FTIR), which clearly shows peak at 1400–1700 cm⁻¹ that confirms the presence of carbonyl group (-COOR-). Thus, the present study provides a competitive analysis for the extraction of bio-oil which is an urgent need to enhance the process for economic sustainability.