Removal of cadmium and lead from soil using aescin as a biosurfactant

Abstract

Remediation of a soil contaminated with cadmium or lead was performed by a soil washing process using aescin as a biosurfactant. The removal of cadmium and lead from the soil was evaluated as a function of aescin concentration and pH in a batch process. A 30-mM aescin solution was most effective in the removal of cadmium and lead at pH 6.8. Cadmium and lead migrated from the soil to the aescin-containing aqueous phase, depending on the pH value. We found that 41% of cadmium (pH 7.8) and 25% of lead (pH 2.8) in the soil matrix migrated into a 30-mM aescin solution. Also, the complexation of aescin with cadmium and lead ions was confirmed by Fourier transform infrared spectroscopy and electrical conductivity measurements. As a result, the maximal complexation capacity of aescin with metal ions was approximately aescin/cadmium = 2:1 and aescin/lead = 3:1 on a molar basis. It was suggested that aescin may sequester cadmium and lead ions by the carboxylic and saccharide moieties. Then, the complex of aescin with cadmium or lead may migrate to the aqueous phase as the result of dispersion. JSD 1, 247-250 (1998). FIG. 3. Shift of carboxylate bands in Fourier transform-infrared spectra of aescin and metal aescinates as evidence for the complexation of aescin with cadmium and lead. FIG. 4. Addition effect of lead ion (3 mM) on electrical conductivity of the aescin solution. FIG. 5. Addition effect of cadmium ion (3 mM) on electrical conductivity of the aescin solution.

Saponin Versus Rhamnolipids for Remediation of Cd Contaminated Soils

“…Zhu et al reported that Cd removal from multi‐metal contaminated soil reached maximum (45.6%) at 5% SAP. Hong et al showed that Cd removal was most effective (41%) at an aescin (SAP mixture) concentration of 3.4%. Chen et al observed that Pb, Cu, and Ni removal with tea SAP increased up to a 1.5% concentration, and that above this concentration removal of all metals plateaued.…”

Humic substances from sewage sludge compost as washing agent effectively remove Cu and Cd from soil

“…Saponin can effectively remove Cd and Zn from clay loam, loam and sandy clay loam (Hong et al, 2002), or Cu and Ni from kaolin (Chen et al, 2008). This is due to the ability of the carboxyl groups on saponin to form complexes with heavy metals, as shown by FTIR analysis (Hong et al, 1998). Similarly, saponin and tannic acid can effectively remove heavy metals and metalloids from both artificially contaminated soils and highly contaminated industrial soils (Gusiatin and Klimiuk, 2012;Gusiatin, 2014).…”

Removal of cadmium or lead from polluted water by biological amphiphiles

“…Recently there has been interest in the application of biological amphiphiles (biosurfactants and naturally occurring acids) to environmental remediation processes (1)(2)(3). They have been successfully used in the treatment of heavy metal-polluted soils and waters (4)(5)(6)(7)(8)(9), and offer the advantages of biodegradability, facile production from renewable resources, selectivity for heavy metals, possible reuse by regeneration, and low toxicity (10)(11)(12). However, being a relatively new area of research, there have been few studies on the applications of biological amphiphiles in heavy metal removal (13).…”