Sorption of sodium dodecylbenzene sulfonate by montmorillonite

Sorption of linear alkylbenzene sulfonates by soils and sediments is an important process that may affect their fate, transport, toxicity and their application in remediation of contaminated soil and groundwater. In this study, batch experiments were conducted to elucidate the sorption of a widely used anionic surfactant, sodium dodecylbenzene sulfonate (SDBS), by montmorillonite. It was observed that: (i) SDBS was sorbed significantly by montmorillonite saturated with Ca2+, but little by Na-saturated montmorillonite; (ii) the amount of SDBS sorbed by Ca2+–montmorillonite was enhanced by NaCl; and (iii) no significant intercalation of SDBS into Ca2+–montmorillonite was observed by X-ray diffraction (XRD) analysis. These results indicate that the removal of SDBS by Ca2+–montmorillonite was primarily attributed to the precipitation between DBS− and Ca2+ in solution which was released from montmorillonite via cation exchange. These results will help us to understand the sorption behavior and environmental effects of anionic surfactants.