Transport and Retention of Nanoscale C_(60) Aggregates in Water-Saturated Porous Media

摘要

Experimental and mathematical modeling studies were performed to investigate the transport and retention of nanoscale fullerene aggregates (nC_(60)) in water-saturated porous media. Aqueous suspensions of nC_(60) aggregates (95 nm diameter, 1 to 3 mg/L) were introduced into columns packed with either glass beads or Ottawa sand at a Darcy velocity of 2.8 m/d. In the presence of 1.0 mM CaCI_2, nC_(60) effluent breakthrough curves (BTCs) gradually increased to a maximum value and then declined sharply upon reintroduction of nC_(60)-free solution. Retention of nC_(60) in glass bead columns ranged from 8 to 49% of the introduced mass, while up to 77% of the mass was retained in Ottawa sand columns. When nC_(60) suspensions were prepared in deionized water alone, effluent nC_(60) BTCs coincided with those of a nonreactive tracer (Br~-), with minimal nC_(60) retention. Observed differences in nC_(60) transport and retention behavior in glass beads and Ottawa sand were consistent with independent batch retention data and theoretical calculations of electrostatic interactions between nC_(60) and the solid surfaces. Effluent concentration and retention profile data were accurately simulated using a numerical model that accounted for nC_(60) attachment kinetics and a limiting retention capacity.