Removal of sulfamethoxazole and ciprofloxacin from aqueous solutions by graphene oxide.

As a promising nanomaterial, graphene-oxide (GO) has shown great sorption potential for environmental contaminants. This study evaluated the ability and mechanism of GO to remove sulfamethoxazole (SMX) and ciprofloxacin (CIP) from aqueous solution. Experimental and modeling results showed that GO effectively sorbed both CIP and SMX with maximum sorption capacity of 379 and 240 mg g(-1), respectively. The sorption of CIP was mainly controlled by the electrostatic attractions; while SMX sorption was mainly though π-π EDA attraction on the basal planes of the GO. Solution pH showed strong effect on the sorption ability of GO to the two antibiotics: at pH of 2, GO sorption ability decreased for both CIP and SMX; at pH of 9, GO completely lost SMX sorption ability but still showed strong sorption to CIP. Both NaCl and CaCl2 decreased CIP sorption onto GO and CaCl2 showed high efficiency even at low ionic strength. The effect of NaCl and CaCl2 on SMX sorption was weaker, but higher ionic strength also reduced the sorption of SMX onto GO. At solution pH of 2, sorption of CIP destabilized GO suspension to form aggregates. Results obtained from this work demonstrated that GO can be used as an effective adsorbents to removal antibiotics from water.