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[PY-49] Adsorption of perchlorate on synthesized gemini surfactants with different chain lengths

○Li Zhang¹, Kancharla Srinivasarao¹, Keiko Sasaki¹ (1. Kyushu University)

Keywords:gemini surfactant, hydrophobicity, adsorption density, perchlorate, quaternary ammonium group

Perchlorate is one of emergent contaminants and known as difficult to immobilize by conventional adsorbents. The difficulty is derived from less hydration of perchlorate. Since quaternary ammonium ions and pyridinium ions have good affinity with perchlorate, several surfactant modified clay have been developed using them as functional groups of the surfactants. In the present work, new series of gemini surfactants, which consists of two amphiphiles bound through a spacer moiety having aromatic hydrocarbons, are synthesized in ionic liquid to characterize by ¹NMR. Highly hydrophobic gemini surfactants with different chain lengths (C14~C20) were successfully synthesized and they are strongly hydrophobic and insoluble in water under room temperature. Adsorption performance of perchlorate by them was directly investigated. Interestingly, perchlorate adsorption density of perchlorate on gemini surfactants with different chain lengths did not always have a positive correlation with its hydrophobicity. The maximum adsorption density of perchlorate was recorded to be 1.7 meq/g when C18 is used. When the chain length is shorter than C18, more hydrophobic surfactant performed higher adsorption capacity of perchlorate. Meanwhile when it is longer than C18, the adsorption capacity of perchlorate decreased. This suggests other factors are behind to affect the adsorption of perchlorate on insoluble surfactants.