Sorption and transport studies of cetyl trimethylammonium bromide (CTAB) and Triton X-100 in clayey soil

Surfactants are soil washing agents and facilitators for subsurface remediation of hydrocarbon spills.It is important to understand the sorption and transport behavior of surfactants for enhanced soil remediation.The adsorption and desorption isotherms of cetyl trimethylammonium bromide (CTAB) and Triton X-100 with sand and kaolinite have been quantified.Kaolinite clay had the highest sorption capacity compared to blasting sand.Transport parameters such as diffusion coefficient (D) and retardation factor (R) of the above mentioned surfactant solutions were determined in clayey soils (82.5% sand and 17.5% kaolinite mixture) with near zero and 0.1 g/L ionic strength.NaCl was used as the electrolyte solution.Convection-Diffusion equation was used to model the breakthrough curves of the surfactants.Bromide ion was chosen as the tracer material in order to characterize the column.CTAB and Triton X-100 were used to flush the perchloroethylene (PCE) contaminated soil.The effectiveness of CTAB and Triton X-100 in flushing the PCE from the contaminated soil was quantified.     

Solubilization and degradation of perchloroethylene （PCE） in cationic and nonionic surfactant solutions

Solubilization of perchloroethylene (PCE) in a nonionic (Triton X-100) and a cationic (cetyltrimethylammonium bromide (CTAB)) surfactant solutions and the degradation of surfactant solubilized PCE using fine to nanosize Fe and bi-metallic Fe-Ni particles were investigated. Micelle partition coefficients (Km) and molar solubility ratio (MSR) for PCE in 10 g/L of surfactant solutions have been quantified and the solubility of PCE (100 mg/L in water) in the surfactant solutions increased by about ten fold. Of the two surfactants studied, Triton X-100 solubilized the higher amount of PCE per gram of surfactant. To degrade solubilized PCE, both iron and bimetallic Fe-Ni particles were used in continuously stirred batch reactors. The iron and bi-metallic particles were synthesized using the solution method and the particles were characterized using the SEM, EDS, TEM and XRD. The PCE solubilized up to 500 mg/L in both surfactant solutions were totally degraded at various rates by 200 g/L of bi-metallic Fe-Ni particles in less than 20 hr, which is the highest concentration of PCE degraded in the shortest time compared to data in the literature. The degradations of PCE solubilized in surfactant solutions were represented by nonlinear kinetic relationships which depended on the type of surfactant used for solubilizing the PCE.