Synergistic remediation of hydrocarbons using a hybrid approach: Harnessing biosurfactant and silver nanoparticles

Abstract

A biosurfactant is an amphiphilic molecule that has both hydrophobic and hydrophilic properties. Biosurfactants from microbial sources with oil degradation potential were isolated from hydrocarbon-contaminated sites. Oil displacement and emulsification tests in this study identified the biosurfactant produced. The biosurfactants produced by the isolated bacteria possess anti-microbial properties. The cell-free supernatants of Bacillus subtilis and Pseudomonas aeruginosa showed positive results for the oil displacement method. The drop collapse test supported the biosurfactant production by these isolates. The synthesis of silver nanoparticles from Acalypha indica plant leaf extract was carried out. The biosurfactants (BS) and silver nanoparticles (AgNP) was also carried out. Their application as individual and synergistic effects in the bioremediation of hydrocarbons (engine waste oil) was discussed. Gravimetric analysis was used to analyse the degradation of engine oil. Silver nanoparticles showed absorbance in the range of 200 and 400 nm. Seven discrete peaks were obtained in FT-IR, representing the main functional group of AgNPs. The reduction of silver nitrate (AgNO3) into silver nanoparticles (AgNP) occurred due to the presence of biomolecules. The SEM analysis showed that the size of the nanoparticle is between 69 and 87 nm and is crystalline. The average distribution of the diameter of the silver nanoparticles was 186.9 nm. Broader peaks of XRD reflect the influence of the experimental circumstances on the nucleation and development of the crystal nuclei and indicate smaller particle sizes. The biosurfactants showed less degradation than the synergistic method employed with biosurfactants and silver nanoparticles. Therefore, it is concluded that the silver nanoparticles influenced the biosurfactant and increased the rate of degradation of the engine waste oil.