Environmental condition effects on radionuclide 64Cu(II) sequestration to a novel composite: polyaniline grafted multiwalled carbon nanotubes

This work examines the sequestration of Cu-64(II) by sorption process onto plasma-induced polyaniline (PANI)-grafted multiwalled carbon nanotubes (denoted as MWCNTs/PANI) prepared by an plasma-induced grafting technique. The role of a variety of environmental conditions such as pH, ionic strength, natural organic matter (NOM) in the sorption of Cu-64(II) onto MWCNTs/PANI is studied. The results indicate that the sorption is strongly dependent on pH but independent of ionic strength. A positive effect of NOM on Cu-64(II) sorption is found at pH < 7.5, whereas a negative effect is observed at pH > 7.5. The sorption isotherms in the absence and presence of NOM can be better described by Freundlich model than Langmuir model. Sorption isotherms of Cu-64(II) at higher initial NOM concentrations are higher than those at lower NOM concentrations. The thermodynamic data calculated from temperature-dependent sorption suggest that the sorption is spontaneous and enhanced at higher temperature. Results of this work suggest that MWCNTs/PANI may be a promising candidate for cost-effective treatments of Cu-64(II)-contaminated wastewaters.