In this study, multiwall carbon annotates (MWNTs) were modified with concentrated sulfuric acid and nitric acid. The activity of f-MWCNTs toward the removal and inactivation of bacteria Gram negative Bacteria (E.coli) were examined. Fourier transformed infrared spectroscopy (FTIR) shows formation of oxygen containing groups such as C=O and COOH. Scanning electron microscopy (SEM) was used to characterize the treated -MWCNTs structure due to oxidation during acid treatment. Moreover, the treated MWCNTs exhibited antimicrobial activities towards E.coli using viable cell technique. Finally, these observations point to the potential use of MWNTs as building blocks for antimicrobial materials.