Complex interplay between formation routes and natural organic matter modification controls capabilities of C_(60)nanoparticles(nC_(60)) to accumulate organic contaminants

摘要

Accumulation of organic contaminants on fullerene nanoparticles(nC_(60)) may significantly affect the risks of C_(60) in the environment.The objective of this study was to further understand how the interplay of nC_(60) formation routes and humic acid modification affects contaminant adsorption of nC_(60).Specifically,adsorption of 1,2,4,5-tetrachlorobenzene(a model nonionic,hydrophobic organic contaminant) on nC_(60) was greatly affected by nC_(60)formation route- the formation route significantly affected the aggregation properties of nC_(60),thus affecting the available surface area and the extent of adsorption via the pore-filling mechanism.Depending on whether nC_(60) was formed via the "top-down" route(i.e.,sonicating C_(60) powder in aqueous solution) or "bottom-up" route(i.e.,phase transfer from an organic solvent) and the type of solvent involved(toluene versus tetrahydrofuran),modification of nC_(60) with Suwannee River humic acid(SRHA) could either enhance or inhibit the adsorption affinity of nC_(60).The net effect depended on the specific way in which SRHA interacted with C_(60) monomers and/or C_(60) aggregates of different sizes and morphology,which determined the relative importance of enhanced adsorption from SRHA modification via preventing C_(60) aggregation and inhibited adsorption through blocking available adsorption sites.The findings further demonstrate the complex mechanisms controlling interactions between nC_(60) and organic contaminants,and may have significant implications for the life-cycle analysis and risk assessment of C_(60).