Colloid Facilitated Ciprofloxacin Transport in Saturated Porous Media.

Ciprofloxacin (CIP) has been frequently detected in water body.  It has been demonstrated to be strongly sorbed in subsurface materials. Mobile colloidal particles may act as carriers to facilitate  CIP transport. This study examined two common soil colloids montmorillinite and kaolinite in facilitating CIP transport in saturated porous media. Laboratory columns packed with quartz sand before (native) and after removing (clean) metal oxides on sand surface were used.  When pre-mixed with CIP, montmorillinite effectively facilitated CIP transport in both clean and native sand  whereas kaolinite facilitated CIP transport only in clean sand. For CIP pre-sorbed sand column, montmorillinite stripped off most of CIP from both clean and native sand surface; however kaolinite only partially stripped CIP off clean sand surface.  Colloid-facilitated transport and stripping effect was impacted by sorption capacity of the colloid and sand matrix.