Adsorptive removal of plasticizer (dimethyl phthalate) and antibiotic (sulfamethazine) from municipal wastewater by magnetic carbon nanotubes

Abstract

In this study, the adsorptive removal of plasticizer (dimethyl phthalate, DMP) and antibiotic (sulfamethazine, SMT) from synthetic and municipal wastewater was studied using multi-wall carbon nanotubes (MWCNTs) and magnetic (Fe3O4) MWCNTs. The competition of SMT and DMP for the adsorptive sites was examined. The adsorption kinetics, isotherms, thermodynamics, as well as the effect of initial pH and competitive adsorption of DMP and SMT were determined. Results showed that both adsorption processes were endothermic, and the maximum adsorption capacity for DMP was calculated to be 196.85 mg g−1 (MWCNTs) and 136.99 mg g−1 (Fe3O4/MWCNTs) at 303 K according to the Langmuir model. The second-order kinetic model and the Freundlich isotherm model could fit the experimental data. In addition, there was a competitive relationship between SMT and DMP for the adsorptive sites of Fe3O4/MWCNTs and MWCNTs, and DMP had obvious competitive effect on the SMT adsorption by Fe3O4/MWCNTs, possibly due to the electrostatic interaction. The adsorption capacity for SMT or DMP decreased in the influent and effluent of municipal sewage plant than that in the deionized water and tap water. Both adsorbents were effective in removal of COD/TOC and targeted pollutants.