Ecotoxicity of multiwalled carbon nanotubes: Standardization of the dispersion methods and concentration measurements

Abstract

There are currently a variety of applications for multiwalled carbon nanotubes (MWCNTs), but considerable concerns exist regarding their release into the environment. Their potential accumulation by aquatic organisms could lead to transfer throughout food chains. Considering the divergences in experimental data published on the ecotoxicity of carbon nanotubes, further research is required. The dispersion of MWCNTs in aqueous culturing media of organisms as well as the determination of concentrations are relevant aspects to obtain accurate ecotoxicity results. Ultraviolet-visible spectroscopy is one of the most reported techniques to analyze concentration quickly and economically, but the methodologies to prepare dispersions and selecting the wavelengths for ultraviolet-visible measurements have not yet been clearly defined. The present study demonstrates that dispersion procedures influence absorbance, and an approach to determine the most appropriate measurement wavelength is proposed. Ecotoxicity tests with MWCNTs were performed on Vibrio fischeri bacteria, and divergences in the results were observed with respect to those previously reported. The present study contributes to the attempt to overcome the lack of standardization in the environmental assessment of MWCNTs.

Tribology: The Tool to Design Materials for Energy-Efficient and Durable Products and Process

“…Artificial intelligence can be also a tool that can facilitate this step forward. Tribology will help to design low carbon footprint materials and implement them in a cost-efficient, predictive, and safe way [70][71][72][73][74][75]. Tribology will assist also the development of energy-and resource-efficient products and processes, in real systems.…”

“…The authors made special mention to those members of the tribology team, that completed their Doctoral Thesis for their contribution to the knowledge generated: Bihotz Pinedo (Tribology of seals 2016) [23][24][25]27], Borja Zabala (high Temperature Tribology (eg. moulds, engines) 2017) [20,22,42,43,46,52], Francesco Pagano, (tribology of ionic liquids and vacuum tribology, 2017) [2-4, 13, 57-65], Beatriz Fernandez-Diaz (tribology of polymers, 2017) [28,34,63], Virginia Saenz de Viteri (biotribology, 2016) [30,31,56,57], Sofia Alves (dental tribology, 2017) [58], Cristina Cerrillo (ecotoxicity of nanoparticles, 2016) [71][72][73][74][75], Ainara López (marine and off shore tribology, 2018) [12][13][14][15][16]. Also, to all the members of the tribology team that dedicate their professional work to tribology activity Elena Fuentes [17,18,30,40,56,57], Xana Fernandez [9, 11, 29, 31, 46-48, 54, 65], Gemma Mendoza [5,11,32,49,50,60,63,[71]…”

Biological response and developmental toxicity of zebrafish embryo and larvae exposed to multi-walled carbon nanotubes with different dimension

“…Pristine (non-functionalized) MWCNTs were weighed and added to distilled water in a 500 ppm final concentration. MWCNTs were homogenized by ultrasonication with a microtip (Mastersize 2000, Malvern Instruments Ltd) in an ice bath, through a program of two pulses of 10 s at 2 W and two pulses of 10 s at 10 W (adapted from (Cerrillo et al., 2015)). This program was done twice, and then zebrafish were incubated with the resulting dispersions.…”

Challenges in characterizing the environmental fate and effects of carbon nanotubes and inorganic nanomaterials in aquatic systems

“…A recent study using a range of non-functionalized MWCNTs investigated the influence of different dispersion preparation techniques on both the comparability of the dispersions and the determination of CNT concentration by UV/ vis absorbance. 64 A sonication process for calibration dispersions using an ultrasonic probe for delivery of acoustic energy was optimized. Verification was conducted by preparing dispersions using an ultrasonic bath, and a procedure to select an appropriate wavelength for each type of MWCNT was also proposed.…”