Assessment of biosurfactant as an emulsifier produced from Bacillus aryabhattai SPS1001 grown on industrial waste coal tar for recovery of bitumen from oil sands

Bacillus aryabhattai SPS1001 grown using a nutrient broth medium supplemented with waste coal tar results in a maximum yield of biosurfactant (0.43 g L−1) and surface tension reduction to 36.55 ± 0.02 mN/m at 48 h whereas emulsification index (E24) with engine oil and mineral oil was measured 88.53% and 89.21%. Emulsion forming and stabilizing efficiency of biosurfactant was retained during exposure to a temperature range (20–121 °C), and salt (NaCl) concentrations up to 12% whereas in the case of pH 6.5 and 7 activity of the biosurfactant dropped significantly and no emulsion formed above pH 11. Quantitative relation of emulsion stability at biosurfactant concentration 0.18 g L−1 was studied in lowering the interfacial tension of engine (2.13 ± 0.9 mN/m) and mineral (3.61 ± 1.9 mN/m) oil at the interface which limits recoalescence of droplets due to Gibbs-Marangoni effect. Zeta potential of the engine and mineral oil emulsions recorded − 23.5 and − 25.5 mV respectively and the polydispersity index (PDI) was measured 0.49 and 1.0 respectively which shows a monodisperse sample indicating the stability of emulsion against droplets coalescence. Structural characterization of biosurfactant by FT-IR reveals strong, broad O–H stretching in alcohol and C-O stretching vibration in primary alcohol respectively and reveals glycolipid nature. Cell-free supernatant containing biosurfactant concentration (0.43 g L−1) was used to recover the bitumen (59%) from oil sands at 70 °C, and the addition of NaCl solution (0.5%) increased the bitumen yield to 63% by decreasing interfacial tension to 0.1 mN/m. Hence, the glycolipid biosurfactant with high and long-term thermostability finds its suitability for biosurfactant-mediated bitumen recovery from oil sand and offers new insight into potential applications in sustainable environmental technologies.