Preparation of ionic liquids/montmorillonite composites and its application for diclofenac sodium removal

Ionic liquid (IL) is an environment friendly organic solvent, which has a relatively low vapor pressure. This work focuses on adsorption of montmorillonite (Mt) to IL as well as removal of diclofenac sodium (DS), an anionic contaminant in water, by IL-modified Mt. The experiment shows absorption of DS increased by increasing IL dosage in modifying Mt. As a result, to modified Mt. with a concentration of IL of 200% cationic exchange capacity (CEC), its static absorption of modified Mt. to DS is 310 mmol/kg, with a rapid rate (reaching balance in 5 min). In dynamic column experiment, absorption of DS reaches balance after 24 h, which absorption amount is 2490 mmol/kg. It can be inferred that modification of IL change surface charge of Mt. and renders intercalation of DS into Mt. interlayers, thus increasing adsorption capacity to DS. These features could further expand the application of ILs and enable IL-modified Mt. to be used as inexpensive sorbents for the removal of chromate and other oxyanions from water.