Transport of surfactant-facilitated multiwalled carbon nanotube suspensions in columns packed with sized soil particles

Transport of carbon nanotubes (CNTs) in soil/sediment matrixes can regulate their potential eco-effects and has been however rarely studied. Herein, column experiments were conducted to investigate mobility of CNT suspensions stabilized by dodecylbenzenesulfonic acid sodium salt (SDBS), octyl-phenol-ethoxylate (TX-100) and cetylpyridinium chloride (CPC) in four soil samples with certain particle sizes. Humic acid was extracted from a soil sample and was coated on quartz sands to explore the effect of soil organic matter (SOM) on the mobility. Results showed that the positively-charged CPC-CNT was entirely retained in the columns while the negatively-charged SDBS-CNT and TX-100-CNT more or less broke through the columns. Pearson correlation analyses revealed that soil texture rather than SOM controlled the mobility. Electrostatic attraction to and/or precipitation on the grain surfaces together with the straining effect could explain the CNT retention. These novel results will help to understand the eco-effects of CNTs. •MWCNTs suspended by different surfactants presented different BTCs in the soils.•Soil texture rather than SOM controlled the CNT transport.•SOM increased the retention of the positively-charged CNT suspension.•Electrostatic attraction, precipitation and straining occurred during the transport. Soil texture and surfactant type control mobility of the surfactant-stabilized CNTs in soils.