Biosurfactant from Candida sphaerica UCP0995 exhibiting heavy metal remediation properties

• A yeast biosurfactant was first evaluated in removing heavy metals in soil.
• The biosurfactant can be used as a cleaning agent for heavy metal remediation.
• The biosurfactant removed 95, 90 and 79% Fe, Zn and Pb, respectively.
• The recycled biosurfactant removed 70, 62 and 45% Fe, Zn and Pb, respectively.
• The biosurfactant also removed 75% Pb and 87% Cd from aqueous solution.

The performance of an anionic biosurfactant from Candida sphaerica in the removal of heavy metals from soil collected from an automotive battery industry and from aqueous solution was evaluated. Multiple combinations of biosurfactant solutions, NaOH and HCl were tested. The results indicated removal rates of 95, 90 and 79% for Fe, Zn and Pb, respectively. The addition of HCl increased the metal removal rate when used with biosurfactant solutions at 0.1 and 0.25%. The use of the recycled biosurfactant after precipitation of the metals in the treated soil demonstrated the ability of the biomolecule to remove 70, 62 and 45% of Fe, Zn and Pb, respectively. Sequential extraction procedures were conducted to determine the speciation of the heavy metals before and after washing the soil with the biosurfactant. The biosurfactant was effective in removing the exchangeable, carbonate, oxide and organic fractions of heavy metals. Tests were performed to evaluate the conductivity and chelating activity of the biosurfactant in aqueous solutions containing Pb and Cd. Atomic absorption spectroscopy studies demonstrated metal removal at a concentration less than the critical micelle concentration. The biosurfactant washing technology is a promising alternative for the remediation of wastewater and soil contaminated with metals.

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