The extracted saponin from ginseng as an efficient renewable biosurfactant for desorption enhancement of phenanthrene and nickel

Biosurfactants, especially plant-derived saponins, are capable of solubilizing and removing both heavy metals and polycyclic aromatic hydrocarbons (PAHs), simultaneously. The purpose of this study was proposing a procedure to extract Korean ginseng saponin (KGS), evaluating the characteristics and thermodynamic parameters of the KGS and exploring the possible application of the KGS for enhancing solubilization and desorption of phenanthrene (as a representative of low molecular weight PAHs) and nickel (as a representative of heavy metals). The KGS can effectively reduce surface tension of water from 73 to 40 Mn m⁻¹ at critical micelle concentration of 0.83 g/L. Analysis of the FTIR data suggested that KGS can form complex with nickel caused by hydroxyl group of saponin; nevertheless, phenanthrene has no significant effect on KGS solution spectra. The solubility of phenanthrene was enhanced about 76-fold by 15 g/L of KGS solution than by pure water. Batch desorption tests were conducted on kaolinite contaminated with phenanthrene (102 mg/kg) and nickel (112 mg/kg). The results showed that 30 g/L KGS can simultaneously remove 79 and 86% of phenanthrene and nickel, respectively. Hence, KGS can be considered as an enhancing agent in remediation technologies of soils contaminated simultaneously with heavy metals and PAHs.