Novel nanobioupgrading of heavy crude oil through simultaneous applying iron oxide nanoparticles and Geobacillus stearothermophilus bacteria

• Qualitative and quantitative analyses to demonstrate Geobacillus stearothermophilus and Iron Oxide Nanoparticles simultaneous application in upgrading heavy oil. • Performance of simultaneous application of Geobacillus stearothermophilus and Iron Oxide Nanoparticles in reducing the Environmentally Hazardous contents. • Performance of simultaneous applying Geobacillus stearothermophilus and Iron Oxide Nanoparticles in increasing Environmentally friendly heavy oil light molecules. • Performance of simultaneous applying Geobacillus stearothermophilus and Iron Oxide Nanoparticles in upgrading heavy oil at reservoir condition. The rising energy demand has amplified the focus on unconventional hydrocarbons, necessitating innovative approaches to upgrading heavy oils. Bioupgrading, while promising, has faced challenges due to its prolonged processing times. Hence, our study delves into the simultaneous application of Geobacillus stearothermophilus ( G. stearothermophilus) bacterium and Iron oxide (Fe 3 O 4 ) nanoparticles on heavy oil upgrading at high temperature. The experiment used Design Expert software's central composite design method by considering the main variables and two independent responses. The results showed that the novel simultaneous nanobiocatalyst could have accelerated the upgrading. The most favorable outcomes were observed during 10.9 days, 25.33% V/V initial oil and 0.46% W nanoparticles, during which FTIR (Fourier-transform infrared spectroscopy) analysis indicated a noteworthy reduction in the aromaticity/aliphatic index from 0.29613 to 0.01178 and a decrease in oil viscosity from 480 cp to its zenith at 87.5 cp. Moreover, as gauged by GC-MS, a remarkable 100% decrease in certain aromatics was exhibited, and considerable improvement in upgrading relative changes (URC) for some contents was observed. Also, asphaltene content was sharply decreased by 74%, which was a 21% improvement in the decreased use of bacteria. These findings highlight G. stearothermophilus and Fe 3 O 4 nanoparticles' synergistic efficacy in upgrading heavy crude oil, offering a promising strategy for addressing energy demands.