( cest2017_00733) Removal of Nitroimidazoles from Aqueous Solutions by Adsorption on Single-Walled Carbon Nanotubes (SWCNT) and Multi-Walled Carbon Nanotubes (MWCNT)

摘要

This work was aimed at investigating theadsorption of metronidazole (MNZ) and dimetridazole,(DTZ) from water onto single-walled carbon nanotubes(SWCNT) and multi-walled carbon nanotubes (MWCNT).The MWCNTs were functionalized by attachingcarboxylic groups (MWCNT-COOH) and by treating withan HNO3 solution (MWCNT-HNO3). The adsorptionequilibrium data were obtained in a batch adsorber andwere interpreted by the Freundlich, Langmuir and Radke-Prausnitz (R-P) isotherms. The R-P isotherm best fitted theexperimental data since its percentage deviation wasalways the lowest. At T=25?C and pH=7, the adsorptioncapacity of the CNTs decreased in the following order:SWCNT > MWCNT > MWCNT-HNO3 > MWNT-COOH,and the maximum adsorption capacities of SWCNTtowards MNZ and DTZ were 101 and 84 mg/g,respectively. The SWCNT had the highest adsorptioncapacity because SWCNT presented the largest surfacearea and was the only CNT with a basic surface. The basicgroups activated the π-π dispersive interactions andfavored the adsorption of the nitroimidazoles. Theadsorption capacity of SWCNT towards MNZ increasedconsiderably by raising the solution pH from 2 to 11, andthis trend was not due to electrostatic interactions. Theadsorption of both nitroimidazoles on the CNTs waspredominantly due to π-π dispersive interactions.