Determination of Phase Distributions for Multi-walled Carbon Nanotubes Between Water and Soils: Limitation of Correlations with K_ow

Abstract

Production and use of carbon nanotubes (CNTs) will unavoidably lead to their disposal in the environment. To assess the risk associated with their release, an understanding of their mobility and ultimate fate is essential. To date, however, relatively little research has been conducted on the fate of CNTs in the environment. In this study, phase distributions of multi-walled carbon nanotubes (MWCNTs) between water and soils were determined by classical laboratory batch experiments and compared with values estimated from several prediction models. Aggregation and subsequent sedimentation appeared to be an important process governing the phase distribution of MWCNTs between water and soils. In this respect, corrected LogK _oc was calculated by excluding the mass of settled MWCNTs and the values were from 3.73 to 4.64. Octanol-water partition coefficient (K _ow) of MWCNTs was also determined to predict the soil sorption property. The LogK _oc values estimated from prediction models were from 1.12 to 2.31. These results indicate that the K _ow alone may not be an appropriate predictor of K _oc for MWCNTs and other predictors or approaches should be explored to accurately estimate the potential mobility of MWCNTs in the environment.

Keywords:

• Multi-walled carbon nanotubes
• phase distribution
• batch experiments
• soil sorption coefficient
• octanol-water partition coefficient

Acknowledgments

This study was supported by the Industrial Core Technology Program (10034759, Risk Management Platform Technology for Nano Products) funded by the Ministry of Trade, Industry and Energy (MOTIE, Korea).