Sorption Of Atrazine Onto CNTs And Their DOM Coated Complexs

In this paper, the sorption and desorption behaviors of atrazine (AT) onto single-walled carbon nanotubes (SWNTs) and multi-walled carbon nanotubes (MWNTs) were studied. The effect of ionic strength and pH were also elucidated. The association of surfactant and natural organic matters (NOM) with carbon nano-tubes (CNTs) not only could increase the mobility of CNTs, but also become a potential carrier for persistent organic pollutants (POPs) and thus make the transport, fate and toxicological effects of POPs more complicated. In this study, MWNTs and SWNTs were modified by humic acids (HA) from different sources and surfactants with different ionic types. The adsorption of atrazine by modified CNTs was investigated and the dispersion stability of modified CNTs was also observed. Physical and chemical properties of different sorbents were analyzed for interpreting sorption mechanisms.Results showed that the ionic strength had no significant influence on the adsorption of AT onto SWNTs and MWNTs. With the increase of pH, the adsorption of AT onto the two nanomaterials increased obviously, which indicated the speciation change of atrazine was the dominant factor controlling the adsorption capacity. The adsorption-desorption curves revealed that no significant desorption hysteresis existed under the condition of this study. High adsorption capacity and adsorption reversibility of atrazine on CNTs implied that CNTs could result in health and environmental risks when applied in large scale. The inhibition effect of peat humic acid (PHA) was relatively stronger than that of soil humic acid (SHA), but the two surfactants had much similar impact on the atrazine adsorption by two CNTs. With the increase of surfactant concentration in solution, the adsorption of atrazine by CNTs decreased rapidly when the surfactant concentration was less than 0.5CMC (Critical Micelle Concentration). Surface modification by humic acid and surfactant could effectively separate MWNTs into well dispersed suspensions, but the SWNTs could not be appreciably dispersed by humic acids and surfactants.