[Virus adsorption onto nano-sized iron oxides as affected by different background solutions]

Batch adsorption studies were conducted to investigate virus adsorption onto four commercial nanoparticles of iron oxide as affected by different background solutions, using bacteriophage phiX174 as virus indicator. When artificial ground water was used, the 4 studied nanoparticles showed high virus adsorption capacity, among which alpha-Fe2O3 was the most effective, with the adsorption percent reaching 100% at low initial virus concentration (i.e. 1E + 03 PFU x mL(-1)). Virus adsorption results were described using the Langmuir and Freundlich adsorption isotherms. The estimated adsorption parameters indicated the presence of multilayer adsorption and favorable adsorption. The adsorption percentage by the studied nanoparticles increased with decreasing virus initial concentration. Our results further showed that higher ionic strength of the background solution reduced the virus adsorption, indicating that electrostatic interaction likely dominated the virus adsorption. The presence of anions in the background solution reduced the virus adsorption, probably because of the competitive adsorption between the viruses and anions for sorption sites available, among which HPO4(2-) showed more reduced than HCO3(-). On the other hand, the presence of multivalent cations was favorable for virus adsorption, with bivalent cations (e.g. Ca2+ and Mg2+) showing more favorable than monovalent cations (e.g. Na+ and K+). Results of this study suggest that nanoparticles of iron oxide may be potentially useful for virus removal from infecting water, while other anions or cations in the water should be considered.