Acute Toxicity of Double‐Walled Carbon Nanotubes to Three Aquatic Organisms

Abstract

This study investigated the toxicity of double walled carbon nanotubes (DWCNTs) to three aquatic organisms, namely,Pseudokirchneriella subcapitata,Daphnia pulex, andPoecilia reticulataunder the influence of exposure media properties specifically the ionic strength and organic matter represented by humic acid. Results indicated that ionic strength enhanced DWCNTs agglomeration whilst humic acid stabilized the CNTs and in turn inhibited the formation of aggregates. LC50s forD. pulexwere higher at 2.81 and 4.45 mg/L for pristine and oxidised DWCNTs, respectively; however,P. reticulatahad lower values of 113.64 mg/L and 214.0 mg/L for the same CNTs correspondingly.P. subcapitatahad EC50s of 17.95 mg/L and 10.93 mg/L for the pristine and oxidised DWCNTs, respectively. In the presence of humic acid high DWCNTs acute toxicity towardsD. pulexandP. reticulatawas observed but ionic strength led to opposite effect irrespective of DWCNTs form. Both humic acid and ionic strength shielded theP. subcapitatafrom toxic effects of DWCNTs. Overall, our findings suggest that the toxicity of DWCNTs in the aquatic systems (i) will be dependent on media properties and (ii) is likely to proceed at different rates to organisms at different trophic levels.

Study of Separately and in Combination Impacts of Zinc-Oxide and Multiwall-Carbon-Nanotube on the Freshwater Prawn (Macrobrachium Nipponense De Haan, 1849), in Laboratory Condition

“…Chang et al (2012) showed that ZnO NMs are highly reactive agents and increase ROS production and cause genotoxicity even at low concentrations in aquatic organisms. Lukhele et al (2015) con rmed the same toxicity effects of MWCNT NMs on three aquatic animals, including Pseudokirchneriella subcapitata, Daphnia pulex, and Poecilia reticulate. In addition to CHH hormone release and SOD enzyme activity, our results showed that in combination, effects of ZnO and MWCNT NMs cause ALT and AST enzymes activities on the M. nipponense muscle tissue while the NMs hadn't shown any impacts on the enzymes as independently at the rst stage of the present study.…”

Electrokinetic Properties of the Pristine and Oxidized MWCNT Depending on the Electrolyte Type and Concentration

“…The increase in the electrolyte concentration from 0.001 to 0.01 M increases the zeta potential electronegativity. So, increasing the concentration of ions with maximum hydration shell, but forming the thickest diffusion layer among the studied solutions, does not lead to a significant reduction in zeta potential and aggregation of the system, as seen in [ 3 ]. The positively charged metal ion neutralizes the surface charge on the surfaces of MWCNTs and compresses the double layer, resulting in the reduction of electrostatic repulsion between nanotubes.…”

“…The stability of the nanotube dispersion mostly depends on the uniformity of the boundary layer and nanotube morphology. The hydrophobic nature of defectless areas of their surface and the hydrophilicity of some types of defects in the nanotube boundary layer, namely carboxy- or phenolic groups [ 2 , 3 ] which are formed during nanotube purification and washing, are competing during dispersing in the aqueous media. An increase in stability of the nanotube dispersion in water can be achieved through the surface charge via formation of the double electrical layer (EDL).…”

Effects of Ingested Multi-Walled Carbon Nanotubes in Poecilia reticulata: Localization and Physiological Responses

“…A portion of these was oxidised by refluxing in 1:3 H 2 SO 4 :HNO 3 for 24 h in order to generate o-MWCNTs. The p-MWCNTs and o-MWCNTs were characterized for their: bands that proved their successful synthesis (Raman spectroscopy, Perkin Elmer Raman nicroscope, RamanMicro 200), shape (A JEOL 100S and Tecnai G2 Spirit transmission electron microscope (TEM)), purity (Energy Dispersive X-ray (EDX) spectroscopy), successful functionalization of p-MWCNTs to o-MWCNTs (Fourier transmission infrared (FTIR), Perkin Elmer Spectrum 100 FTIR spectrometer) prior to the toxicity studies [28]. The characterization techniques gave an insight to the physical properties and chemical composition of the MWCNTs.…”