Showing papers by "Xiaolei Qu published in 2011"

Probing the specific sorption sites on montmorillonite using nitroaromatic compounds and hexafluorobenzene.

Abstract: The objective of this work was to test two possible sorption mechanisms of organic chemicals to montmorillonite: n−π electron-donor−acceptor (EDA) interaction with lone electron pairs of siloxane oxygens (n-donors) and complexation with exchangeable cations. Batch sorption experiments were performed for 1,3-dinitrobenzene, 1,4-dinitrobenzene (π-electron acceptors and cation binders), and hexafluorobenzene (π-electron acceptor only) to homoionic montmorillonites in water or hexane. For all three sorbates, the aqueous sorption affinity showed large cation dependency (Cs+ > K+ > Na+), wherein sorption of hexafluorobenzene to Cs+−montmorillonite was the strongest (Kd in the order of 104 L/kg). Change of the solvent media from water to hexane generally favored sorption, indicating suppressive effect by cation hydration. Cosorption of 1,4-dinitrobenzene prominently decreased sorption of 1,3-dinitrobenzene to all cation-exchanged montmorillonites; however, hexafluorobenzene caused strong competition only to Cs+−...