Past and present dispersion state strongly affects the sorption behavior of carbon nanotubes
- Author(s)
- Thilo Hofmann, Mélanie Kah, Xiaoran Zhang, Michiel T.O. Jonker
- Abstract
CNTs have strong sorption affinity towards organic compounds. Understanding the influence of dispersion/aggregation on sorption is essential for evaluating CNT’s potential environmental impact and their application as superior sorbent. However, there is currently very limited data on the sorption potential of partially/fully dispersed CNT systems. This can be mainly explained by limitations associated with the generally-applied batch sorption test setup that does not allow investigations on dispersed systems.
We applied a passive sampling method to investigate the influence of dispersion state on the sorption behaviour of CNTs. The objectives were to investigate the effect of (i) CNT pre-treatments (sonication, shaking) and (ii) natural dispersants on the sorption characteristics of the CNT system. Single point sorption coefficients and sorption isotherms for pyrene were measured over a wide range of concentrationand in the presence of HA (1-200 mg L-1). CNT suspensions were extensively characterized in order to support mechanistic interpretations of the results.
Results indicated that dispersion can significantly affect the sorption behaviour of CNTs. On the one hand, sonication broke down CNT aggregates and greatly increased pyrene sorption (sorption increased by 1.4 orders of magnitude). Sorption surfaces newly exposed during sonication remained available to pyrene molecules even if re-aggregation occurred, supporting an irreversible effect of sonication. On the other hand, the presence of HA decreased the sorption of pyrene. At the highest HA concentration investigated (200 mg L-1), sorption was still 1.6 orders of magnitude stronger than sorption of pyrene to HA itself. This indicates that specific interactions between pyrene and CNTs are still occurring, in spite of a HA coating of the CNTs’ surface. A greater suppression of sorption by HA occurred when combined with a sonication pre-treatment.
Sorption isotherm fitting indicated that the maximum sorption capacity, affinity and heterogeneity of CNTs surface were all affected by sonication and the presence of HA. The present results contribute to an improved understanding of the sorption behaviour of CNTs in both natural and waste water systems.
- Organisation(s)
- External organisation(s)
- Utrecht University
- Publication date
- 2012
- Austrian Fields of Science 2012
- 105303 Hydrogeology, 104023 Environmental chemistry, 105105 Geochemistry, 105904 Environmental research
- Portal url
- https://ucrisportal.univie.ac.at/en/publications/185886ce-2af3-447e-8e5f-33c6acdfd299