Silver nanoparticles attached to porous carbon substrates: robust materials for chemical-free water disinfection

The antibacterial properties of silver are well known, and their potency can strongly depend on the available surface area. Nanoparticles provide the advantage of high surface area per volume, but their use is limited because, once deployed in the environment, they are difficult to retrieve and may become pollutants with potential adverse effects. This issue can be addressed if silver nanoparticles (AgNP) are attached to or encased in larger structures. This research focuses on attachment of AgNP on robust lightweight and tailorable structures of carbon that are easy to handle, yet offer high surface area thereby providing the nanomaterial advantage without the risk of agglomeration, loss, and environmental contamination. Silver nanoparticles were deposited on carbon foams via chemical reduction of silver nitrate in the presence of reducing and capping agents. Scanning electron microscope pictures show AgNP distribution throughout the porous structure. The antibacterial capacity of the prepared structure was tested against influent water contaminated with Gram negative Escherichia coli (E. Coli, JM109) strain of bacteria. The effectiveness of these materials has been demonstrated in two different water flow configurations, rotation in storage containers and incorporation in active or passive filters. These results clearly indicate that incorporation of AgNP onto porous carbon structures is a promising approach to fluid disinfection. There is ample scope for future refinement of these materials through modification of silver concentration, surface areas, flow rates, and/or electric fields. (C) 2013 Elsevier B.V. All rights reserved.