Purification, Characterization, and Oil-Displacement Performance of Rhamnolipid Biosurfactant Produced by Bacillus...

Area of Science:

• Biotechnology and Bioprocess Engineering
• Petroleum Engineering
• Environmental Science

Background:

• Rhamnolipids are effective biosurfactants for enhanced oil recovery (EOR).
• Biosafety concerns exist with commonly used rhamnolipid-producing strains.
• There is a need for safe and efficient biosurfactants for EOR applications.

Purpose of the Study:

• To isolate and characterize a novel rhamnolipid-producing bacterium from oily sludge.
• To evaluate the physicochemical properties and EOR performance of the produced rhamnolipid (DQ-Rha).
• To assess the biosafety profile of DQ-Rha through acute oral toxicity testing.

Main Methods:

• Isolation and cultivation of Bacillus sp. DQ-4 from oily sludge.
• Purification and structural characterization of DQ-Rha using spectroscopic techniques (TLC, FTIR, MALDI-TOF MS, NMR).
• Evaluation of surface tension reduction, oil spreading, emulsification, oil washing efficiency, micromodel, and core flooding experiments. Acute oral toxicity testing in ICR mice.

Main Results:

• Bacillus sp. DQ-4 successfully produced rhamnolipids (DQ-Rha) with a confirmed structure.
• DQ-Rha significantly reduced surface tension and showed excellent oil-spreading and emulsification properties.
• DQ-Rha demonstrated comparable EOR performance to commercial rhamnolipids in micromodel and core flooding experiments, with an acute oral LD50 > 5000 mg/kg.

Conclusions:

• Bacillus sp. DQ-4 is a promising source for producing safe and effective rhamnolipid biosurfactants.
• DQ-Rha exhibits significant potential for enhanced oil recovery applications due to its performance and low toxicity.
• This study contributes a viable, biosafety-conscious alternative for the oil industry.