title: Effects of polyethyleneimine-mediated functionalization of multi-walled carbon nanotubes on earthworm bioaccumulation and sorption by soils.
abstract: Carbon nanotubes (CNTs) are often modified for different intended potential applications to enhance their aqueous stability or change properties such as surface charge. Such changes may also profoundly impact their environmental behaviors. Herein, we report the effects of modifying (14)C-labeled multiwalled carbon nanotubes (MWCNTs) with polyetheyleneimine (PEI) surface coatings to render them more stable in solution and to give them positive, negative, or neutral surface charges. These carbon nanotubes were used to test their sorption by soils and uptake and elimination behaviors by earthworms. Sorption results indicate nearly linear sorption isotherms for regular MWCNTs and nonlinear isotherms for modified MWCNTs, indicating that the PEI coatings influenced MWCNT interactions with soils. Nevertheless, there were minimal differences in the sorption results among the different soils for each type of nanotube despite differences in the soil organic carbon and cation exchange capacities. Differences in uptake behaviors by earthworms were not apparent among different types of PEI-MWCNTs and MWCNTs with limited absorption into organism tissues consistently observed. Elimination patterns were well fit with an exponential decay model suggesting that the worms can readily eliminate any accumulated MWCNTs.
authors: Material Measurement Laboratory, National Institute of Standards and Technology , Gaithersburg, Maryland 20899, United States. Elijah.Petersen@nist.gov
authors: Elijah J
authors: EJ
authors: Petersen
authors: Roger A
authors: RA
authors: Pinto
authors: Liwen
authors: L
authors: Zhang
authors: Qingguo
authors: Q
authors: Huang
authors: Peter F
authors: PF
authors: Landrum
authors: Walter J
authors: WJ
authors: Weber
mesh_terms: D000327:Adsorption; D000818:Animals; D037742:Nanotubes, Carbon / Q000737:chemistry / Q000633:toxicity*; D009835:Oligochaeta / Q000187:drug effects* / Q000378:metabolism; D011094:Polyethyleneimine / Q000737:chemistry / Q000378:metabolism / Q000633:toxicity*; D012987:Soil / Q000737:chemistry*; D012989:Soil Pollutants / Q000737:chemistry / Q000378:metabolism / Q000633:toxicity*; D013499:Surface Properties
chemical_list: D037742:Nanotubes, Carbon; D012987:Soil; D012989:Soil Pollutants; D011094:Polyethyleneimine