Single-walled carbon nanotube transport in representative municipal solid waste landfill conditions

Single-walled carbon nanotubes (SWNTs) are being used in many consumer products and devices. It is likely that as some of these products reach the end of their useful life, they will be discarded in municipal solid waste landfills. However, there has been little work evaluating the fate of nanomaterials in solid waste environments. The purpose of this study is to systematically evaluate the influence of organic matter type and concentration in landfill-relevant conditions on SWNT transport through a packed-bed of mixed municipal solid waste collectors. The influence of individual waste materials on SWNT deposition is also evaluated. Transport experiments were conducted through saturated waste-containing columns over a range of simulated leachate conditions representing both mature and young leachates. Results indicate that SWNT transport may be significant in mature waste environments, with mobility decreasing with decreasing humic acid concentration. SWNT mobility in the presence of acetic acid was inhibited, suggesting their mobility in young waste environments may be small. SWNTs also exhibited collector media-dependent transport, with greatest transport in glass and least in paper. These results represent the first study evaluating how leachate age and changes in waste composition influence potential SWNT mobility in landfills.