Narrow Carbon Research Articles

Management of Cassava Starch Factory Solid Waste (Thippi) through Composting to a Nutrient-Rich Organic Manure

ABSTRACTIn India, cassava cultivation is confined in South India. In Tamil Nadu, tubers are used as raw material for starch and sago industry. About 8–10 large-scale starch factories and 150–200 small-scale starch and sago production units are generating nearly 40–60 tonnes of solid waste (thippi) per annum creating serious environmental pollution. A study undertaken to manage it through composting to a nutrient-rich organic manure revealed thippi as acidic with low major and micronutrient concentration, high water-holding capacity, good porosity, low bulk density, high starch, fiber, low protein, and cyanide. Composting of thippi with different combinations of raw materials, microbial cultures, and earthworms indicated that thippi enriched with gliricida and cassava leaves and composted with earthworm had the highest nutrient concentration with narrow carbon to nitrogen (C:N) ratio. The mean concentrations of N, phosphorus (P), potassium (K) calcium (Ca) and magnesium (Mg), iron (Fe), manganese (Mn), copper (Cu), and zinc (Zn) in thippi compost were 1.32, 3.82, 0.40, 2.18, 0.96, 1.11, 0.08%, 11.23, and 89.93 mg/kg, respectively, which is 3.5, 49,7, 32.5, 8, 185, 100, 2.5, and 12 times than thippi. Thippi compost had low bulk density, starch, without fiber and cyanide but high protein suggesting this protocol as a possible alternative for the management of thippi.

Atomic layer deposition of Al2O3 catalysts for narrow diameter distributed single-walled carbon nanotube arrays growth

Taking the importance of uniform size catalysts and the unfavorable effects of residual metal catalysts into consideration, herein, we develop a facile way which utilizes the typical and facile semiconducting technique namely atomic layer deposition (ALD) to prepare non-metallic Al2O3 catalysts for narrow diameter single-walled carbon nanotube (SWNT) arrays growth. As a result, we obtained SWNT arrays with narrow-diameter distribution of 1.26 ± 0.033 nm on the a-plane sapphire substrates. Moreover, the relationship between catalysts and SWNTs were explored. These optimized conditions pave an avenue for narrow diameter even chirality distribution in SWNTs growth, which promotes the development of structure-controlled and relative applications of SWNTs.

Effect of temperature and diameter of narrow single-walled carbon nanotubes on the viscosity of nanofluid: A molecular dynamics study

Equilibrium molecular dynamics simulations by all-atom model have been employed to investigate the adsorption properties and temperature dependence of the shear viscosity of ethanol molecules confined in narrow single-walled carbon nanotubes (SWCNTs). Since the properties of the narrow tubes (diameters < 7 Å) are strongly influenced by their curvature, the narrow SWCNTs with diameters ranging from 0.54 to 1.08 nm and the length of 2.5 nm in ethanol reservoir at 273.0, 298.0 and 323K and 1 bar have been studied. The results indicate that endo-adsorption occurs in nanotubes with the diameter larger than 0.81 nm and as a result ethanol nano-wires can be formed inside nanotubes.Calculations of shear viscosity of the nanofluid using Green–Kubo method reveal that the relative viscosity of the confined ethanol decreases with increasing temperature.All the CNT@ethanol fluids have lower viscosity than the base liquid ethanol at all temperatures and the viscosity increases with the increase of CNT radius and endo-adsorption.Chirality of the CNTs has minor effects on shear viscosity and endo-adsorption and the main factor is CNTs diameter.The results of the present work provide deep understanding of the viscosity changes with temperature at the nanofluids and can describe the mechanisms for base fluid property modifications caused by adding nanoparticles. These results are applicable in design and preparation of diesohols and fuel-grade ethanol.

Unique magnetic and thermoelectric properties of chemically functionalized narrow carbon polymers

We analyze magnetic, transport and thermoelectric properties of narrow carbon polymers, which are chemically functionalized with nitroxide groups. Numerical calculations of the electronic band structure and the corresponding transmission function are based on density functional theory. Transport and thermoelectric parameters are calculated in the linear response regime, with particular interest in charge and spin thermopowers (charge and spin Seebeck effects). Such nanoribbons are shown to have thermoelectric properties described by large thermoelectric efficiency, which makes these materials promising from the application point of view.

Chirality effect on Lithiation of narrow carbon nanotubes; bond order MD and DFT studies

Bond order force field molecular dynamic simulation and also a complimentary density functional theory method are employed for lithiation of narrow carbon nanotubes (CNTs). Since interior region of the narrow tubes (diameters < 7 Å) is strongly influenced by their walls’ ‘curvature effect’, endo-lithiation occurs via formation of lithium chains. Whereas, in the case of exo-lithiation the absorbed lithium atoms form coaxial cylinders up to radiuses of 12 Å. Meanwhile, although to some extent chirality of the CNTs has minor effects on endo-litiation’s distribution, the main factor in the total lithium storage capacity is the diameter. In addition, to obtain more applicable results this study is extended also for a bundle of the CNTs and it is seen that the adsorption energy and also the storage capacity enhance about 1.5 times.

Optimal shape of entrances for a frictionless nanochannel

In a nearly frictionless channels such as narrow carbon nanotubes, flow is limited by the viscous dissipation occurring at the tube mouth. Using both numerical and analytical approaches, it is demonstrated that such end effects can be reduced to a considerable extent by adding an entrance of well-chosen shape.

Tunable Electronic and Magnetic Properties of Transition Metal-Cyclopentadiene Sandwich Molecule Wires Functionalized Narrow Single Wall Carbon Nanotubes

The structural, electronic, and magnetic properties of 1D organometallic molecule wires functionalized narrow single wall carbon nanotube, [TMCp]∞/SWCNTs (TM = Sc, V, Mn, Fe, Co, SWCNTs, (n, m) = (7,7), (10,0), (11,0)), are first studied by density functional theory calculations. In the case of the 1D [TMCp]∞ wires encapsulated in SWCNTs, the reaction between 1D [TMCp]∞ and SWCNTs are endothermic or exothermic depending on the diameters of SWCNTs, while the dimension confinement effect disappears through placing the organometallic molecular wires outside the SWCNTs. Moreover, obvious ionic bonding nature is identified in the systems by putting the 1D [TMCp]∞ wire in or outside of the SWCNTs. In contrast, stronger covalent bonding nature is found for the derivatives by desorption of one raw of hydrogen atoms in the cyclopentadiene ligands. In particular, diverse electronic and magnetic properties are introduced by the choice of SWCNTs and the functionalized 1D [TMCp]∞ wires, which allows the 1D [TMCp]∞/SWCNTs wires to function as a basic building block for potential application in electronic- and spintronic-based devices.

Thermoelectric phenomena in chemically synthesized graphene nanoribbons with substitution atoms and functional groups

AbstractWe analyze theoretically electronic, magnetic, and thermoelectric properties of narrow carbon polymers. Such nanoribbons, which can be obtained chemically via bottom‐up approach from the appropriate monomers, may exhibit extremely interesting properties from application point of view if modified with substitution Al/N atoms or functionalized with NOCH3 group. Our investigations, based on ab initio calculations, show that such modification may considerably narrow the bandgap with respect to pristine structures. Also, magnetic moments ordered ferromagnetically can be generated along modified edges, which results in the spin dependent band structure giving rise to remarkable spin effects, giving strongly enhanced spin Seebeck coefficient. These results suggest that modified polymeric graphene nanoribbons would have a great potential for applications in spintronic devices.

Effects of water-channel attractions on single-file water permeation through nanochannels

Single-file transportation of water across narrow nanochannels such as carbon nanotubes has attracted much attention in recent years. Such permeation can be greatly affected by the water-channel interactions; despite some progress, this issue has not been fully explored. Herein we use molecular dynamics simulations to investigate the effects of water-channel attractions on occupancy, translational (transportation) and orientational dynamics of water inside narrow single-walled carbon nanotubes (SWNTs). We use SWNTs as the model nanochannels and change the strength of water-nanotube attractions to mimic the changes in the hydrophobicity/polarity of the nanochannel. We investigate the dependence of water occupancy inside SWNTs on the water-channel attraction and identify the corresponding threshold values for drying states, wetting-drying transition states, and stably wetting states. As the strength of water-channel attractions increases, water flow increases rapidly first, and then decreases gradually; the maximal flow occurs in the case where the nanochannel is predominately filled with the 1D water wire but with a small fraction of ‘empty states’, indicating that appropriate empty-filling (drying-wetting) switching can promote water permeation. This maximal flow is unexpected, since in traditional view, the stable and tight hydrogen-bonding network of the water wire is the prerequisite for high permeability of water. The underlying mechanism is discussed from an energetic perspective. In addition, the effect of water-channel attractions on reorientational dynamics of the water wire is studied, and a negative correlation between the flipping frequency of water wire and the water-channel attraction is observed. The underlying mechanism is interpreted in term of the axial total dipole moment of inner water molecules. This work would help to better understand the effects of water-channel attractions on wetting properties of narrow nanochannels, and on single-file water permeation through nanochannels, which might be helpful in designs of high-flux nanochannels.

Chirality effect on nearly half-metallic properties in systematic endo-doping of 3d transition metals of narrow carbon nanotubes

Spin polarized density functional calculations were employed to study chirality effect on electronic and magnetic properties of 3d transition metals (TMs) endo-doped co-diameter (∼7Å) narrow (5,5) and (9,0) single walled carbon nanotubes (CNTs). Various magnetizations up to ∼6μB was obtained for different 3dTM-CNT systems (recall that the magnetization of fcc structure cobalt is ∼1.6μB). In addition nearly half-metallic magnetic behavior has been observed for the most of considered systems. These results would be useful for spintronic and nano-magnetic technology.

Salt Solutions in Carbon Nanotubes: The Role of Cation−π Interactions

Understanding the structure of aqueous electrolytes at interfaces is essential for predicting and optimizing device performance for a wide variety of emerging energy and environmental technologies. In this work, we investigate the structure of two common salt solutions, NaCl and KCl, at a hydrophobic interface within narrow carbon nanotubes (CNTs). Using a combination of first-principles and classical molecular dynamics simulations in conjunction with molecular orbital analysis, we find that the solvation structure of the cations in the CNTs can deviate substantially from the conventional weakly interacting hydrophobic picture. Instead, interactions between solvated ions and π orbitals of the CNTs are found to play a critically important role. Specifically, the ion solvation structure is ultimately determined by a complex interplay between cation−π interactions and the intrinsic flexibility of the solvation shell. In the case of K+, these effects result in an unusually strong propensity to partially desol...

From dimers to collective dipoles: Structure and dynamics of methanol/ethanol partition by narrow carbon nanotubes.

Alcohol partitioning by narrow single-walled carbon nanotubes (SWCNTs) holds the promise for the development of novel nanodevices for diverse applications. Consequently, in this work, the partition of small alcohols by narrow tubes was kinetically and structurally quantified via molecular dynamics simulations. Alcohol partitioning is a fast process in the order of 10 ns for diluted solutions but the axial-diffusivity within SWCNT is greatly diminished being two to three orders of magnitude lower with respect to bulk conditions. Structurally, alcohols form a single-file conformation under confinement and more interestingly, they exhibit a pore-width dependent transition from dipole dimers to a single collective dipole, for both methanol and ethanol. Energetic analyses demonstrate that this transition is the result of a detailed balance between dispersion and electrostatics interactions, with the latter being more pronounced for collective dipoles. This transition fully modifies the reorientational dynamics of the loaded particles, generating stable collective dipoles that could find usage in signal-amplification devices. Overall, the results herein have shown distinct physico-chemical features of confined alcohols and are a further step towards the understanding and development of novel nanofluidics within SWCNTs.

Review on ZnO hybrid photocatalyst: impact on photocatalytic activities of water pollutant degradation

AbstractZinc oxide (ZnO) is one of the most widely used benchmark standard photocatalysts in the field of environmental applications. However, the large band gap of ZnO and the massive recombination of photogenerated charge carriers, especially in its nanosize, limit the overall photocatalytic efficiency. This can be further overcome by modifying the electronic band structure of ZnO by hybridization with a narrow band gap material, including metal, metal oxide, carbon based, and polymeric based. Indeed, ZnO hybridization with the respective materials contributed to its sensitizer by shifting the absorption wavelength to the visible region of the spectrum. This review encompasses several advancements made in the mentioned aspects, and also some of the new physical insights related to the charge transfer events, such as charge carrier generation, trapping, detrapping, and their transfer to surface, are discussed for each strategy of the hybrid ZnO. The synergistic effects in the mixed polymorphs of ZnO and also the theories proposed for their enhanced activity are reported. The review also highlights the potential application of ZnO hybrid for different kinds of pollutants from different wastewater sources.

Interactions of anions and cations in carbon nanotubes.

We consider the insertion of alkali-halide ion pairs into a narrow (5,5) carbon nanotube. In all cases considered, the insertion of a dimer is only slightly exothermic. While the image charge induced on the surface of the tube favors insertion, it simultaneously weakens the Coulomb attraction between the two ions. In addition, the anion experiences a sizable Pauli repulsion. For a one dimensional chain of NaCl embedded in the tube the most favorable position for the anion is at the center, and for the cation near the wall. The phonon spectrum of such chains shows both an acoustic and an optical branch.

Giant Raman Response to the Encapsulation of Sulfur in Narrow Diameter Single-Walled Carbon Nanotubes.

Encapsulation of sulfur in HiPCO-SWNTs leads to large changes in the Raman spectra with the appearance of new peaks at 319, 395, and 715 cm(-1) which originate from the sulfur species within the SWNTs, while the high frequency SWNT bands (ν > 1200 cm(-1)) are decreased in intensity. The encapsulated species also shifts the near-IR interband electronic transitions to lower energy by more than 10%. These effects seem to originate with the van der Waals interaction of the confined sulfur species with the walls of the SWNTs which are not expected to be significant in the case of the previously studied large diameter SWNTs. We suggest that sulfur in the small diameter SWNTs exists as a helical polymeric sulfur chain that enters the SWNT interior in the form of S2 ((3)Σ(g)(-)) molecules which undergo polymerization to linear diradicals.

On the Energetics of Ions in Carbon and Gold Nanotubes

We investigate the insertion of halide and alkali atoms into narrow single-walled carbon nanotubes with diameters <9 Å by density functional theory; both chiral and non-chiral tubes are considered. The atoms are stored in the form of ions; the concomitant charge transfer affects the band structure and makes originally semiconducting tubes conducting. The electrostatic interaction between a charge and the walls of the tube is explicitly calculated. The insertion energies and the positions of the ions are determined by a competition between electrostatic energy and Pauli repulsion. For comparison, we consider ions in gold nanotubes. Alkali ions follow the same principles in gold as in carbon tubes, but chloride is specifically adsorbed inside gold tubes.

Characterization of Vanadyl and Nickel Porphyrins Enriched from Heavy Residues by Positive-Ion Electrospray Ionization FT-ICR Mass Spectrometry

Petroporphyrins were enriched and purified from atmospheric residues of two typical heavy oils, Canadian oil sand bitumen (OSAR: Ni, 80 ppm; V, 190 ppm; S, 3.97 wt %) and Chinese Liaohe heavy oil (LHAR: Ni, 68.7 ppm; V, 1.81 ppm; S, 0.36 wt %) by silica-gel chromatography. The separation and purification were confirmed by atomic absorption spectroscopy (AAS) combined with UV–vis spectroscopy, and the petroporphyrins were characterized by positive-ion electrospray ionization (ESI) Fourier transform–ion cyclotron resonance mass spectrometry (FT-ICR MS). Vanadyl and nickel porphyrins in OSAR are simultaneously identified by mass measurement and isotopic fine structure. Vanadyl porphyrins with structures of N4VO, N4VO2, and N4VOS are all detected as protonated analyte ([M + H]+). Both molecular ion (M+•) and protonated analyte ([M + H]+) as well as their corresponding isotopes are observed for N4Ni porphyrins in OSAR and LHAR with an average mass resolving power of over 400000 (m/Δm50%). This is rarely detected by FT-ICR MS using ESI technique previously. Formation of molecular ion can be attributed to the low oxidation potential of nickel porphyrins, the effect of oil matrix on the solution conductivity, and the relatively low flow rate of solution into the capillary. Three more highly unsaturated types of N4VO porphyrins were identified in addition to the six well-documented structures. Compared to N4VO porphyrins, N4VOS porphyrins present higher DBE ranging from 21 to 27 while N4VO2 porphyrins show lower DBE ranging from 18 to 20 and narrower carbon number distribution, suggesting possible different origins of sulfur (pyrolysis of kerogen) and oxygen (diagenesis of chlorophyills). Ni/V and the ratio of relative abundance of ETIO porphyrins to DPEP porphyrins (∑ETIO/∑DPEP) for nickel porphyrins indicate that Liaohe oil and Canadian oil sand bitumen are continental and marine sediments, respectively, and Liaohe oil has a higher maturity. Enrichment by the simple chromatographic method facilitates the mass spectral identification of nickel porphyrins even for heavy residue with low content of nickel and high content of sulfur.

Electronic property and charge carrier mobility of extended nanowires built from narrow graphene nanoribbon and atomic carbon chain

This work presented theoretical studies on the extended nanowires constructed from narrow graphene nanoribbons and atomic carbon chains by using self-consistent field crystal orbital method based on density functional theory. The size and connection effects on geometrical structure, relative stability and electronic property of these one-dimensional (1D) nanowires have been addressed systemically and in details. It is found that the ratio of narrow graphene nanoribbons and CC units may be the key factor to the relative thermodynamic stability of these 1D wires based on the obtained Gibbs free energy. All the extended nanowires studied have a direct band gap according to the calculated electronic band structures. The obtained band gaps of the nanowires are in the range of 0.918–2.015eV. These flexible band gaps imply the possibility to modulate the electronic properties of these extended wires by turning the sizes and connections. Furthermore, a quantitative relation between the band gap and the ratio of phenylene and CC units is obtained. Moreover, we calculate the charge carrier mobility of the extended nanowires based on the deformation potential theory and effective mass approach. The frontier crystal orbital analyses are performed to get a better understanding of the charge carrier mobility for the 1D nanowires with various sizes and connections.

Mechanisms of Hydrogen Transport in Flexible‐Wall Narrow Carbon Nanotubes

Understanding the interaction between hydrogen and carbon nanotubes is crucial to enhancing the performance of hydrogen storage and nanofluidic carbon‐adsorbent systems. Accordingly, this study performs a series of molecular dynamics simulations to investigate the transport properties of hydrogen molecules confined within a flexible narrow carbon nanotube. The tube’s diameter is 10.8 Å at temperatures in the range of 100~800 K. The particle loadings inside carbon nanotubes are ranging from 0.01∼1 No/Å. The results show that the hydrogen molecules exhibit three distinct diffusion regimes, namely, single‐file, Fickian, and ballistic, depending on the value of the Knudsen number. In addition, it is shown that with the Knudsen number of less than 1, the tube‐wall long wavelength acoustic phonons induced Rayleigh traveling wave prompts a longitudinal wave slip and compression‐expansion of the hydrogen molecule crowds within the CNT, which leads to a significant increase in the mean square displacement of the molecules.

A political–industrial ecology of water supply infrastructure for Los Angeles

This paper develops a political–industrial ecology approach to explore the urban water metabolism of Los Angeles, which sprawls for thousands of miles across the American West. Conventional approaches to quantify urban carbon footprints rely on global, national, or regional averages and focus narrowly on improving the efficiency of flows of resources moving into and out of the city. These approaches tend to “black box” the methodologies that guide the carbon emissions calculus and the social, political, ecological, and economic processes that perpetually reshape nature–society metabolisms. To more fully delineate the water supply metabolism of Los Angeles, this paper combines theory and method from urban political ecology and industrial ecology. Specifically, we infuse spatiality into the traditional life-cycle assessment (LCA) approach by coupling it with GIS. By illustrating how decisions about system boundaries, emissions factors, and other building blocks fundamentally shape the end result, this intervention at once destabilizes and advances the LCA enterprise. Then, using interviews and historical analysis, we provide a critical analysis of how LA’s various water supply infrastructures came to be and illustrate how a sustainable transition based on a narrow carbon calculus is problematized by historical circumstances and strategic (and often conflicting) new paradigms to secure water resources. The political–industrial ecology approach offers valuable insights into the spatiality of material metabolisms and the socio-political processes (re)shaping the relations between nature and society.