Electrochemical Multiwalled Carbon Nanotube Filter for Viral and Bacterial Removal and Inactivation

Department of Chemical and Environmental Engineering, Yale University , New Haven, Connecticut 06520-8286, United States.
Environmental Science & Technology (Impact Factor: 5.33). 03/2011; 45(8):3672-9. DOI: 10.1021/es2000062
Source: PubMed


Nanotechnology has potential to offer solutions to problems facing the developing world. Here, we demonstrate the efficacy of an anodic multiwalled carbon nanotube (MWNT) microfilter toward the removal and inactivation of viruses (MS2) and bacteria (E. coli). In the absence of electrolysis, the MWNT filter is effective for complete removal of bacteria by sieving and multilog removal of viruses by depth-filtration. Concomitant electrolysis during filtration results in significantly increased inactivation of influent bacteria and viruses. At applied potentials of 2 and 3 V, the electrochemical MWNT filter reduced the number of bacteria and viruses in the effluent to below the limit of detection. Application of 2 and 3 V for 30 s postfiltration inactivated >75% of the sieved bacteria and >99.6% of the adsorbed viruses. Electrolyte concentration and composition had no correlation to electrochemical inactivation consistent with a direct oxidation mechanism at the MWNT filter surface. Potential dependent dye oxidation and E. coli morphological changes also support a direct oxidation mechanism. Advantages of the electrochemical MWNT filter for pathogen removal and inactivation and potential for point-of-use drinking water treatment are discussed.

Download full-text


Available from: Jessica D Schiffman
  • Source
    • "For the coating strategy, the durability of the coated layer of conductive materials was normally questionable. Carbon nanotubes (CNTs), owing to their superior electrical conductivity and physicochemical stability, have drawn much attention as an ideal conductive material [26] [27] [28] [29] [30] [31] [32]. Polyvinylidene fluoride (PVDF), as one of the most extensively used membrane materials, is well known for its outstanding mechanical strength, chemical resistance, and thermal stability [33] [34] [35]. "
    [Show abstract] [Hide abstract]
    ABSTRACT: Electrically conductive membrane possesses a remarkable performance in antifouling with the assistance of applied external electric fields. However, its widespread application is hampered due to the poor properties of existing conductive membranes, such as low conductivity and inadequate strength. The present study demonstrates a novel in-situ combination approach for the fabrication of a highly conductive carbon nanotube (CNT)/polyvinylidene fluoride (PVDF) membrane. During membrane fabrication, the casting solution film was pre-mantled with a CNT layer before the occurrence of polymer precipitation, thereby ensuring a natural and tight in-situ mergence between the CNT layer and supporting PVDF. The obtained CNT/PVDF membrane was characterized in terms of physicochemical properties and filtration performance. An electrically-enhanced cross-flow filtration system was devised to evaluate the antifouling performance of the pristine PVDF and CNT/PVDF membranes. Compared with the pristine PVDF membrane, the CNT/PVDF membrane possesses a greater electrical conductivity and a higher permeability. The incorporation of the CNT layer led to a completely different surface composition in terms of elemental components and functional groups. Being used as a cathode, the CNT/PVDF membrane exhibited a remarkable antifouling performance in the presence of external electric fields, and performed better in a 0 V/2 V-pulsed mode as compared with a 2 V-constant mode. This in-situ combination method provides a simple and practical approach for the fabrication of composite conductive membranes, suggesting promising applications in various membrane-fabrication areas.
    Full-text · Article · Oct 2015 · Journal of Membrane Science
  • Source
    • "Dissolved natural organic matter (NOM) in drinking water sources can pose problems for water quality and treatment processes , including making contributions to disinfectant byproduct formation[1]Contents lists available at ScienceDirectThese sorbents have been incorporated into woven mat configurations as filters or sorbents45678, impregnated onto membranes to enhance removal of targeted organic molecules through sorption processes[9], or used for improved biocidal properties[10]. This work investigates interactions between dissolved NOM and commercially-obtained graphene sheets in order to evaluate their potential use in water treatment technologies. "
    [Show abstract] [Hide abstract]
    ABSTRACT: Nanosized graphene materials are being considered as a class of new, high surface area sorbents suitable for water treatment applications. This study explored commercially available graphene powders of differing sizes, surface areas, and surface compositions for their ability to sorb dissolved natural organic matter (NOM) from water under varying solution conditions within batch reactors. The sorption kinetics of NOM on graphene powders were rapid and reached equilibrium within hours. Sorption isotherms for all graphenes and all NOM types were all best described with the Freundlich model. Sorption affinity improved with increasing graphene specific surface area, more graphene carbon content, greater NOM aromatic content, and lower solution pH. Graphene sorption behavior is compared to carbon nanotubes and granular activated carbon, and high surface area graphene may possess superior sorption rates and capacities, whereas low surface area graphene may be entirely ineffective. The high surface area graphene examined here also showed selectivity for the aromatic and high molecular weight NOM fractions within measurements of specific UV absorbance and size exclusion chromatography. The results suggest that aromatic interactions significantly participate in NOM binding, but that electrostatic interactions may also influence sorption capacity depending on solution pH and graphene surface charge.
    Full-text · Article · Aug 2015 · The Chemical Engineering Journal
  • Source
    • "Therefore, FCV can be electrochemically inactivated without risk of producing DBPs. Using the proposed method, FCV may be oxidized via the electrode surface, as described previously [16] [17] [18]. Because the major capsid protein was not fragmented or degraded following electrochemical treatment (Fig. 3), the protein oxidation may contribute to FCV inactivation. "
    [Show abstract] [Hide abstract]
    ABSTRACT: Pathogenic viral infections are an international public health concern, and viral disinfection has received increasing attention. Electrochemical treatment has been used for treatment of water contaminated by bacteria for several decades, and although in recent years several reports have investigated viral inactivation kinetics, the mode of action of viral inactivation by electrochemical treatment remains unclear. Here, we demonstrated the inactivation of feline calicivirus (FCV), a surrogate for human noroviruses, by electrochemical treatment in a developed flow-cell equipped with a screen-printed electrode. The viral infectivity titer was reduced by over 5 orders of magnitude after 15 min of treatment at 0.9 V vs. Ag/AgCl. Proteomic study of electrochemically inactivated virus revealed oxidation of peptides located in the viral particles; oxidation was not observed in the non-treated sample. Furthermore, transmission electron microscopy revealed that viral particles in the treated sample had irregular structures. These results suggest that electrochemical treatment inactivates FCV via oxidation of peptides in the structural region, causing structural deformation of virus particles. This first report of viral protein damage through electrochemical treatment will contribute to broadening the understanding of viral inactivation mechanisms.
    Full-text · Article · Oct 2014 · Journal of Hazardous Materials
Show more