Characterization of functionalized multiwalled carbon nanotubes and application as an effective filter for heavy metal removal from aqueous solutions☆

Filtration efficiency of Ni(II) from aqueous solution using pristine and modified MWCNTs filters was investigated as a function of Ni(II) ion concentration, pH, and filter mass. MWCNTs were synthesized by CVD method and modified using two complementary treatments, purification (using a mixture of hydrochloric acid and hydrogen peroxide) and functionalization (using nitric acid). The effect and mechanism of each treatment on the structural integrity of pristine MWCNTs has been studied. Morphology of the pristine and modified filters was investigated by Raman Spectrometry (RS), Scanning Electron Microscopy (SEM), Energy Dispersive X-ray Spectroscopy (EDS), Fourier Transform Infrared (FTIR) spectrometry and Thermogravimetric analysis. It was found from Raman spec-tra that the ratio of the intensity of D-band to that of G-band decreased by purification process, and increased by functionalization process. The adsorption mechanism of Ni(II) onto the surface functional groups of modified MWCNTs was confirmed by FTIR spectrum. The filtration results showed that the removal efficiency of Ni(II) is strongly dependent on pH and could reach 85%at pH=8. Also, modified MWCNT filters can be reused through many cycles of regeneration with high performance. Functionalized MWCNTs filters may be a promising adsor-bent candidate for heavy metal removal from wastewater.     

Antimicrobial activity of functionalised carbon nanotubes against pathogenic microorganisms

Carbon nanotubes represent one of the best examples of novel nanostructures, exhibit a range of extraordinary physical properties, strong antimicrobial activity and can pierce bacterial cell walls. This investigation handles the antimicrobial activity of functionalised multiwall carbon nanotubes (F‐MWNTs) as an alternative antimicrobial material compared to the commercial antibiotics. Antibacterial activities of F‐MWNTs are investigated through two different kinds of bacteria, E. coli and S. aureus. The results demonstrate that the best concentration of F‐MWNTs for the maximum inhibition and antibacterial functionality is 80 and 60 μg/ml for E. coli and S. aureus, respectively. The transmission electron microscope reveals the morphological changes damage mechanism for the cellular reliability on these microorganisms. F‐MWNTs are capable of biologically isolating the cell from their microenvironment, contributing to the development of toxic substances and placing the cell under oxidative stress leading to cellular death. The efficiency of F‐MWNTs is compared with the common antibiotics and shows an enhancement in the inhibitory effect with percentages reaches 85%. To account for the bactericidal performance of F‐MWNTs towards these pathogens, the dielectric conductivity and the bacterial growth measurements are conducted. The present study endeavour that F‐MWNTs could be exploited in biomedical devices and altering systems for hospital and industrial cleaning applications.Inspec keywords: antibacterial activity, biomedical materials, microorganisms, cellular biophysics, toxicology, nanomedicine, multi‐wall carbon nanotubes, transmission electron microscopy, electrical conductivity, permittivityOther keywords: F‐MWNTs, pathogenic microorganisms, antimicrobial activity, bacterial cell walls, functionalised multiwall carbon nanotubes, antibacterial activity, E. coli, S. aureus, antimicrobial material, physical properties, transmission electron microscopy, morphological changes, damage mechanism, cellular reliability, microenvironment, toxic substances, oxidative stress, cellular death, bactericidal performance, dielectric conductivity, bacterial growth measurements, biomedical devices, C