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Carbon nanotubes (CNTs) are promising for realizing ultrafast membranes with implications to molecular separations and beyond. However, it is a big challenge to harness the potential of CNTs for designing scalable yet high-performance membranes. Here we systematically explore the role of loading and vacuum-assisted alignment of CNTs for improving the desalination performance of polyamide (PA) based thin-film composites. To rule out the dispersion instability issues, we focused on carboxylated single-walled CNTs (SWCNTs) commercially available in the market. After applying a pre-treatment for cleaning, we deposited SWCNTs on porous polysulfone supports by vacuum filtration and coated a PA layer on top via interfacial polymerization. Morphological assessments supported by polarized Raman microspectroscopy allowed the quantification of SWCNT alignment. At an optimum SWCNT loading, which we found critical for alignment, the water permeability of resulting membranes significantly improved without compromising NaCl selectivity. Also, we achieved an improved boric acid selectivity, arguably owing to the hydrophobic nature of nanotube channels. Moreover, nanotubes promoted resistance against chlorine degradation and improved mechanical strength. Vacuum deposition is instrumental for infiltrating SWCNTs into the support layer, but a mat layer forms between the support and PA layers when SWCNT loading exceeds the limit that the support pores can accommodate. Given that we use ordinary SWCNTs and a scalable methodology (vacuum-assisted infiltration), the developed membranes are promising for practical applications. © 2021 Elsevier Ltd

Reducing animal use in biosensor research requires broader use of in vitro methods. In this work, we present a novel application of Franz cells suitable for biosensor development and evaluation in vitro. The work describes how Franz cell can be equipped with electrodes enabling characterization of biosensors in close proximity to skin. As an example of a sensor, hydrogen peroxide biosensor was prepared based on horseradish peroxidase (HRP)/single-walled carbon nanotube (SWCNT)-modified textile. The electrode exhibited lower detection limit of 0.3 μM and sensitivity of 184 μA mM−1 cm−2. The ability of this biosensor to monitor H2O2 penetration through skin and dialysis membranes was evaluated in Franz cell setup in amperometric and wireless modes. The results also show that catalase activity present in skin is a considerable problem for epidermal sensing of H2O2. This work highlights opportunities and obstacles that can be addressed by assessment of biosensors in Franz cell setup before progressing to their testing in animals and humans.

Background: Drugs, especially antibiotics, are one of the serious problems of modern life and the main pollution sources of the environment, especially in the last decade, which are harmful to human health and environment. The aim of this study was to investigate the removal of penicillin G from aqueous solutions using single-walled and multi-walled carbon nanotubes. Methods: In this study, the effect of different parameters including pH (3, 5, 7, 9, and 11), initial concentration of pollutant (50, 100, 150, and 200 mg/l), absorbent dose (0.25, 0.5, 0.75, and 1 g/L), mixing speed (0, 100, 200, and 300 rpm), and temperature (10, 15, 25, 35, 45°C) were investigated. The Langmuir, Freundlich, Temkin, BET, Dubinin-Radushkevich isotherms and adsorption kinetics of the first- and second-order equations were determined. Results: The results showed that the efficiency of single-walled and multi-walled carbon nanotubes in the removal of penicillin G was 68.25% and 56.37%, respectively, and adsorption capacity of the nanotubes was 141 mg/g and 119 mg/g at initial concentration of 50 mg/l and pH=5 with adsorption dose of 0.8 g/L for 105 minutes at 300 rpm and temperature of 10°C from aqueous solutions. Also, it was revealed that the adsorption process had the highest correlation with the Langmuir model and secondorder kinetics, and the maximum adsorption capacity based on Langmuir model was 373.80 mg/g. Conclusion: According to the results, it was found that single-walled and multi-walled carbon nanotubes can be used as effective absorbents in the removal of penicillin G from aqueous solutions. Keywords: Single-walled carbon, Multi-walled carbon, Adsorption, Penicillin G, Antibiotics

Cracks are one of the primary forms of damage that can lead to the catastrophic failure of metallic structures. This study focuses on the application of epoxy nanocomposite thin film sensors for continuous monitoring of crack evolution in metallic structures. The core approach was to monitor the current (or resistance) change in these nanocomposite films, as cracks develop and propagate in the metallic host structure. Based on optical, electrical, and mechanical properties of epoxy resins modified with different contents of single-walled carbon nanotubes, two different nanocomposites (with 0.3 and 1.0 wt%) were chosen for the development of a crack sensor. The performance of the nanocomposite sensors was evaluated under tension–tension fatigue tests, on aluminum coupons with centrally located through thickness electrical discharge machining notches. Crack growth in the aluminum was found to transfer to the nanocomposite films in a stable mode. Once the crack was established, a linear correlation was found between the measured current and crack length with a slope of −10−11 and −10−8 A/mm for 0.3 and 1.0 wt% nanocomposites, respectively. Contact between the asperities formed on the crack surfaces in the nanocomposite film while the crack was closed at small loads (−1. In summary, the nanocomposite thin film sensor developed in this study offers both continuous crack growth monitoring and the possibility of strain sensing. The sensor is also suitable for visual inspection of the host structure due to the transparency of the developed nanocomposite film.

A triply fused porphyrin dimer bearing long alkyl chains for enhanced solubility was prepared and investigated for its ability to supramolecularly functionalize single-walled carbon nanotubes. It was found that this porphyrin dimer indeed binds strongly to the nanotube surface, allowing the removal of excess unbound porphyrin from solution without diminishing nanotube solubility. UV-vis spectroscopy indicated a bathochromic shift of the porphyrin Soret band upon binding to the nanotube surface, while Raman spectroscopy indicated that functionalization with the porphyrin dimer does not lead to any defects being formed on the nanotube wall. Transmission electron microscopy revealed the presence of individual nanotubes and small nanotube bundles that were heavily coated with porphyrin dimers. Comparison to analogous fused dimers bearing tert-butyl groups for solubility clearly demonstrated that long alkyl chains are necessary for prolonged solution stability of the nanotube complexes. While a previously investigated tert-butyl derivative was found to bind to the nanotube surface, the resulting complex precipitated out of solution within minutes. It was also found that the position of bulky substituents on the porphyrin dimer had a dramatic effect on whether it was able to interact with the nanotube surface. © 2011 American Chemical Society.

The radio frequency (RF) inductively coupled plasma technique is a new and promising synthesis method of single-walled carbon nanotubes (SWCNTs) at large scales, for industrial and commercial applications. In this method, a mixture of carbon black and metal catalysts is directly vaporized by the RF plasma. Subsequently, inside the reactor chamber and under a controlled temperature gradient, carbon-metal clusters are formed and become the potential sites for nucleation and growth of SWCNTs. In this process, the local plasma properties and the thermo-fluid field in the system affect the yield rate of SWCNTs, and therefore it is important to find an appropriate operating condition, which maximizes the yield rate. Numerical modeling in conjunction with experimental studies can help investigate the contribution of the thermo-fluid field and process parameters to the formation of catalyst nanoparticles and carbon nanotubes in the induction thermal plasma system. The goal of this research is to carry numerical study of SWCNT growth in a RF induction thermal plasma system with a suitable chemistry model. This model is employed to investigate the influence of the thermo-fluid field and gas-phase reactions on carbon nanotube growth and to predict the SWCNT yield rate as a function of operating conditions. © 2011 by JSME.

Köçkar, Hakan (Balikesir Author), In this paper we report the electrical characteristics of the Schottky diodes formed by surface polymerization of the Poly(ethylene glycol dimethanylate-n-vinyl imidazole)/Single Walled Carbon Nanotubes on n-Si The Single Walled Carbon Nanotubes were synthesized by CVD method. The main electrical properties of the Poly(ethylene glycol dimethanylate-n-vinyl imidazole)/Single Walled Carbon Nanotubes/n-Si have been investigated through the barrier heights, the ideality factors and the impurity density distribution, by using current-voltage and reverse bias capacitance voltage characteristics. Electrical measurements were carried out at room temperature. Poly(ethylene glycol dimethacrylate-n-vinyl imidazole)/Single Walled Carbon Nanotubes/n-Si Schottky diode current-voltage characteristics display low reverse-bias leakage currents and average barrier heights of 0.61 +/- 0.02 eV and 0.72 +/- 0.02 eV obtained from both current-voltage and capacitance-voltage measurements at room temperature, respectively.

2D axisymmetric numerical calculations are conducted to model the thermo-fluid fields and chemical reactions leading to the formation of SWCNTs in an RF plasma system. A modified version of the SWCNT "reduced" chemical model is used to estimate the formation of SWCNT in an RF plasma system for the first time. The "reduced" model incorporates 14 species and 36 chemical reactions to predict the formation of metal and carbon clusters and SWCNTs. By combing the chemistry model into the RF plasma CFD code, the formation and development of carbon and metal catalyst clusters and their reactions which produce SWCNTs are shown. The chemistry model is shown to under-predict the yield rate of SWCNT. In order to better predict the yield rate, a sensitivity analysis is performed to modify the dominant reaction rates. The modified model predicts the yield of SWCNTs correctly within the range reported experimentally. However, more studies should be conducted to validate the accuracy of the model for different operating conditions., 12th High-Tech Plasma Processes Conference, HTPP 2012, 24 June 2012 through 29 June 2012, Bologna

Single-walled carbon nanotubes (SWCNTs) were produced by an electric arc process in a low-pressure chamber with vertical electrodes using heterogeneous graphite anodes containing nickel and yttrium catalysts. The influence of the chamber volume (18, 25 and 60 L) and graphite grain size (1 and 100 µm) of the anode on the resulting products was analysed. This was correlated with the physical properties of the plasma as studied by optical emission spectroscopy and with the temperature of the gaseous atmosphere surrounding the plasma as measured using thermocouples. Nanotube yield and purity were evaluated from high-resolution transmission electron microscopy. Results showed a strong influence of the heterogeneous anode grain size. It was found that the optimal synthesis conditions correspond to an arc chamber volume of 25 L and a graphite grain size of 1 µm. In that case the plasma temperature and the carbon over nickel concentration ratio in the plasma differ notably from those observed under the other synthesis conditions. It was also found that a slower temperature rise of the gaseous atmosphere surrounding the plasma and a higher anode erosion rate are associated with a higher SWCNT yield. These results were interpreted considering the vapour–liquid–solid nanotube formation model.

A Radio Frequency (RF) inductively coupled plasma technique is a new and promising synthesis method of Single-Walled Carbon Nanotubes (SWCNTs) at large scales, for industrial and commercial applications. With this method, a mixture of carbon black and metal catalysts is directly vaporized by a plasma jet, generated from an induction plasma torch. Subsequently, inside a reactor chamber, and under a controlled temperature gradient, carbon-metal clusters are formed and become the potential sites for the nucleation and growth of SWCNTs. In this process, the local plasma properties and the thermo-fluid field in the system affect the yield rate of SWCNTs, thus it is important to find an appropriate operating condition, which maximizes the yield rate. Numerical modeling in conjunction with experimental studies can help investigate the contribution of the thermo-fluid field and process parameters in the formation of catalyst nanoparticles and carbon nanotubes in the induction thermal plasma system. The goal of this work is to perform CFD simulations of the RF thermal plasma process in the synthesis of SWCNT in order to numerically study the thermo-flow fields inside the synthesis system. The effect of thermal conductivity of the reaction chamber's graphite liners were also investigated on the flow and the temperature fields in the system. The thermal conductivity of the graphite liners was measured at different temperatures and implemented into the CFD code. The comparison between our current simulations with our previous results indicates that the thermal conductivity profile of the graphite liners imposes variations on the flow and the temperature fields inside the reaction chamber. © 2011 by the American Institute of Aeronautics and Astronautics, Inc. All rights reserved., 42nd AIAA Plasmadynamics and Lasers Conference 2011, 27 June 2011 through 30 June 2011, Honolulu, HI

We review the current achievements in the numerical studies of adsorption of molecular hydrogen in boron substituted nanoporous carbons. We show that the enhanced attraction of H-2 by boron-substituted all-carbon structures may allow designing new porous materials with modulated capacity for hydrogen adsorption. Such new structures are characterized by modification of energy landscape of adsorbing surfaces extending beyond the vicinity of substituted atom over several graphene carbon sites, and show strong surface heterogeneity. Although the theoretical conception and description of boron-substituted carbons made a considerable progress during the last decade, the preparation of these materials involves tedious procedures and still needs to be improved.