Submitted to: Environmental Geosciences
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 2/13/1998
Publication Date: N/A
Interpretive Summary: Ten commercially available cationic surfactants were screened for their ability to remove lead from soils. The objective was to determine with batch equilibrium testing if cationic surfactants can remove lead from soils by varying surfactant concentrations and pH conditions. Three of ten screened cationic surfactants, Isostearamidopropyl Morpholine Lactate (ISML), Lapyrium Chloride (LC), and Dodecyl Pyridinium Chloride (DPC) showed the highest potential in desorbing lead. Lead desorption from Salughterville sandy loam and Teller loam was dependent on surfactant solution concentration, pH, soil type, and soil pH. With decreasing pH of surfactant solution to pH 4, lead desorption increased. Up to pH 6, the desorption was mainly ion exchange. Overall, at highest studied solution concentration of 0.1 mole/L, and at constant concentration of 0.025 mole/L with varied pH, ISML was the best surfactant in desorbing lead from two soils. Sandy loams and sandy soils with pH between 5 to 6 are good candidates for lead removal up to 83 percent using cationic surfactants. These results provided valuable information on feasibility of using surfactants for environmental remediation of heavy metals from contaminated sites and outlined the direction for future research.
Technical Abstract: The feasibility of using cationic surfactants to desorb lead from contaminated soil was investigated by a two-phase batch testing. In phase I, lead desorption from the Slaughterville sandy loam was measured as a function of surfactant concentration for ten cationic surfactants. In Phase II, Slaughterville and Teller loam soils were used to measure the impact of pH on surfactant desorption of lead. During this phase, pH was varied over the range of 4 to 9, while the surfactant concentration was kept constant at 0.025 mole/L. Phase I results indicate that three of ten surfactants, Isostearamidopropyl Morpholine Lactate (ISML), Lapyrium Chloride (LC), and Dodecyl Pyridinium Chloride (DPC) are clearly better in desorbing lead. At concentration 0.1 mole/L, ISML, LC, and DPC desorbed 82, 59 and 50% of lead, respectively, from Slaughterville. Phase II results show that lead desorption by surfactant solutions 0.025 mole/L to be pH dependent. As pH decreased, desorption of lead increased. At a pH 4, ISML, LC, and DPC desorbed 83, 78, and 68% lead, respectively, from Slaughterville, and 36, 32, and 29% Pb from Teller loam. These results support the feasibility of using cationic surfactants in lead removal and other heavy metals from fine-grained soil.