Green biocide for mitigating sulfate-reducing bacteria influenced microbial corrosion

Area of Science:

• Materials Science
• Microbiology
• Environmental Science

Background:

• Sulfate-reducing bacteria (SRB) are significant contributors to microbially influenced corrosion (MIC) in industrial settings, particularly in the oil and gas sector.
• Traditional biocides can pose environmental risks, necessitating the development of eco-friendly alternatives.

Purpose of the Study:

• To evaluate the efficacy of Polyalthia longifolia plant extract (PLAE) as a novel biocide against SRB-induced corrosion.
• To investigate the mechanism by which PLAE inhibits SRB and mitigates corrosion.

Main Methods:

• Transmission electron microscopy (TEM) and scanning electron microscopy (SEM) were used to observe the effects of PLAE on SRB morphology.
• Energy-dispersive Fourier transform infra-red spectroscopy (ED-FTIR) was employed to analyze changes in sulfide concentration.
• Potentiodynamic polarization and gravimetric mass loss tests were conducted to assess the corrosion rate of mild steel in the presence and absence of PLAE.

Main Results:

• TEM and SEM confirmed that PLAE damages the outer cell membrane of SRB, leading to cell destruction and shrinkage.
• ED-FTIR indicated a reduction in sulfide concentration when PLAE was applied.
• Potentiodynamic polarization and gravimetric analysis showed a significant decrease in the corrosion rate of mild steel, from 0.064 mm/year to 0.013 mm/year, in the presence of PLAE.

Conclusions:

• Polyalthia longifolia plant extract demonstrates potent biocidal activity against SRB.
• PLAE effectively mitigates SRB-induced corrosion by disrupting bacterial cell integrity and reducing sulfide production.
• P. longifolia extract presents a promising, novel, and eco-friendly biocide for controlling corrosion in the oil and gas industry.