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Artur P Terzyk - One of the best experts on this subject based on the ideXlab platform.

  • first molecular dynamics simulation insight into the mechanism of organics adsorption from aqueous solutions on microporous Carbons
    Chemical Physics Letters, 2011
    Co-Authors: Artur P Terzyk, Sylwester Furmaniak, Piotr A Gauden, Wojciech Zielinski, Radoslaw P Wesolowski, Kamil K Klimek
    Abstract:

    Abstract The results of 84 MD simulations showing the influence of porosity and Carbon Surface oxidation on adsorption of three organic compounds from aqueous solutions on Carbons are reported. Based on a model of ‘soft’ activated Carbon, three Carbon structures with gradually changed microporosity were created. Next, different number of Surface oxygen groups was introduced. We observe quantitative agreement between simulation and experiment i.e. the decrease in adsorption from benzene down to paracetamol. Simulation results clearly demonstrate that the balance between porosity and Carbon Surface chemical composition in organics adsorption on Carbons, and the pore blocking determine adsorption properties of Carbons.

  • the influence of the Carbon Surface chemical composition on dubinin astakhov equation parameters calculated from sf6 adsorption data grand canonical monte carlo simulation
    Journal of Physics: Condensed Matter, 2011
    Co-Authors: Sylwester Furmaniak, Artur P Terzyk, Piotr A Gauden, Piotr Kowalczyk, Peter J F Harris
    Abstract:

    Using grand canonical Monte Carlo simulation we show, for the first time, the influence of the Carbon porosity and Surface oxidation on the parameters of the Dubinin–Astakhov (DA) adsorption isotherm equation. We conclude that upon Carbon Surface oxidation, the adsorption decreases for all Carbons studied. Moreover, the parameters of the DA model depend on the number of Surface oxygen groups. That is why in the case of Carbons containing Surface polar groups, SF6 adsorption isotherm data cannot be used for characterization of the porosity.

  • molecular properties and intermolecular forces factors balancing the effect of Carbon Surface chemistry in adsorption of organics from dilute aqueous solutions
    Journal of Colloid and Interface Science, 2004
    Co-Authors: Artur P Terzyk
    Abstract:

    Presented paper recapitulates the results of 6 years' study concerning the effect of Carbon Surface chemical composition on adsorption of paracetamol, phenol, acetanilide, and aniline from dilute aqueous solutions on Carbons. Adsorption-desorption isotherms, enthalpy, and kinetics of adsorption data are shown for the measurements performed at three temperatures (300, 310, and 320 K) at two pH levels (1.5 and 7) on commercial activated Carbons. The data were obtained for four Carbons: the initial Carbon D43/1 and forms modified by applying concentrated HNO3, fuming H2SO4, and gaseous NH3. The modification procedures do not change the porosity in a drastic way, but lead to drastic changes of the composition of Carbon Surface layer. By applying MOPAC (a general-purpose semiempirical molecular orbital package), the physicochemical constants characterizing the molecules of adsorbates are calculated, including the distribution of the Mulliken charges, the dipole moments and ionization potentials, and the energies of interaction with the unique positive and negative charges. They are correlated with the parameters characterizing the adsorption (and kinetics) process of studied molecules on the mentioned above Carbons. The mechanisms proposed in the literature for the description of adsorption from dilute aqueous solutions are verified, and a general mechanism of adsorption is proposed.

  • The influence of activated Carbon Surface chemical composition on the adsorption of acetaminophen (paracetamol) in vitro
    Colloids and Surfaces A: Physicochemical and Engineering Aspects, 2001
    Co-Authors: Artur P Terzyk
    Abstract:

    Abstract The presented paper is the subsequent one of the series concerning the results of the influence of Carbon Surface chemical composition on paracetamol adsorption from water solutions. The non-modified de-ashed commercial Carbon D43/1, (Carbo-Tech, Essen, Germany) as well as modified ones (using conc. nitric acid, fuming sulphuric acid, ammonia, and modified via ionic exchange process with Cu2+) were used as adsorbents. For these, characterised previously, Carbons the results of some additional measurements, i.e. thermogravimetry in He and in air, FTIR, and XPS are reported, to expose the type of Carbon Surface groups created by chemical modifications. The results of kinetic measurements (performed at three temperatures: 300, 310 and 320 K) are reported. They were described using very simple kinetic equation proposed by Korta and co-workers; moreover, this equation has been modified in the current paper. It is shown that, up to the relative adsorption value equal to 0.5 the kinetics of the process of paracetamol adsorption is determined by the hydrophilicity of Carbon Surface. The rate of this process increases linearly with the values of the enthalpy of Carbon immersion in water. Moreover, for all the Carbons, except for the modified one with Cu2+, the rate of adsorption is determined by the presence of Surface groups and it increases with the total acidity of Carbon.

Jacques Simonet - One of the best experts on this subject based on the ideXlab platform.

  • Enolization versus Carbonylation at glassy Carbon Surface through cathodic means
    Electrochemistry Communications, 2013
    Co-Authors: Jacques Simonet
    Abstract:

    The cathodic reduction of ω-bromomethylarylketones in aprotic organic solvents (such as propylene Carbonate) containing tetraalkylammonium iodides achieved at smooth glassy Carbon (GC) permits through a selective one-electron reduction, the scission of the Csingle bondBr bond. Quite unexpectedly, the free radical thus formed is prior attached to the Carbon Surface in its enolic form (GCsingle bondOsingle bond(Ar)Cdouble bond; length as m-dashCH2). Successive radical addition processes may lead to a redox polymer based on the one-electron oxidation of enol ethers. The average superficial enol concentration at the Carbon Surface (found to be about 2.5 × 10− 8 mol cm− 2) was assessed by the halogen index (iodine or bromine) via halogen addition to the double bonds followed by the micro-coulometric reduction of the resulting vicinal di-halo compounds.

  • Enolization versus Carbonylation at glassy Carbon Surface through cathodic means
    Electrochemistry Communications, 2013
    Co-Authors: Jacques Simonet
    Abstract:

    Abstract The cathodic reduction of ω-bromomethylarylketones in aprotic organic solvents (such as propylene Carbonate) containing tetraalkylammonium iodides achieved at smooth glassy Carbon (GC) permits through a selective one-electron reduction, the scission of the C Br bond. Quite unexpectedly, the free radical thus formed is prior attached to the Carbon Surface in its enolic form (GC O (Ar)C CH 2 ). Successive radical addition processes may lead to a redox polymer based on the one-electron oxidation of enol ethers. The average superficial enol concentration at the Carbon Surface (found to be about 2.5 × 10 − 8  mol cm − 2 ) was assessed by the halogen index (iodine or bromine) via halogen addition to the double bonds followed by the micro-coulometric reduction of the resulting vicinal di-halo compounds.

  • Glassy Carbon perceived as graphitized material. Cathodic charge and reactivity toward alkyl halides. A new concept in Surface modifications of Carbons
    Electrochemistry Communications, 2011
    Co-Authors: Jacques Simonet
    Abstract:

    Glassy Carbon was reported to be efficient in two-electron reductive scission of alkyl halides RX for leading to RH. When organic solvents are used, it is shown that, within the potential range [−1.5 V to −3 V], the electrochemical process is complicated to a large extend by the progressive alkylation of the Carbon Surface until the formation of compact films composed of immobilized alkyl groups. It is proposed that behaviour be related to the presence of graphitized zones at the glassy Carbon Surface. These large zones of sp2 Carbons can be transformed under electrochemical charge into nucleophilic belts for reacting towards RXs via a kind of heterogeneous SN2. This interfacial process independently coexists with that governed by electron transfers (ET). Therefore, the nature of the scission (pure electron exchange process) with the transient formation of a radical Rradical dot, should be re-considered according to the real reactivity of the Carbon Surface, the electrophilicity of the RX and the applied potential. Additionally, this simple procedure may lead to an efficient way for grafting alkyl links and tagging to their extremity several chemical functions.

Philippe Hapiot - One of the best experts on this subject based on the ideXlab platform.

  • Design of robust binary film onto Carbon Surface using diazonium electrochemistry.
    Langmuir, 2011
    Co-Authors: Yann Leroux, Fei Hui, Jean-marc Noël, Clément Roux, Alison J. Downard, Philippe Hapiot
    Abstract:

    The electroreduction of functionalized aryldiazonium salts combined with a protection-deprotection method was evaluated for the fabrication of organized mixed layers covalently bound onto Carbon substrates. The first modification consists of the grafting of a protected 4-((triisopropylsilyl)ethynyl)benzene layer onto the Carbon Surface on which the introduction of a second functional group is possible without altering the first grafted functional group. After deprotection, we obtained an ultrathin robust layer presenting high densities of both active ethynylbenzene groups (available for "click" chemistry) and the second functional group. The strategy was successfully demonstrated using azidomethylferrocene to react with ethynyl moieties in the binary film by "click" chemistry, and NO(2)-phenyl as the second functional group. Two possible modification pathways with different orderings of the various steps were considered to show the influence and importance of the protection-deprotection process on the final Surface obtained. Using mild conditions for the grafting of the second layer maintains a concentration of active ethynyl groups similar to that obtained for a one-component monolayer while achieving a high Surface concentration of the second modifier. Considering the wide range of functional aryldiazonium salts that could be electrodeposited onto Carbon Surfaces and the versatility and specificity of the "click" chemistry, this approach appears very promising for the preparation of mixed layers in well-controlled conditions without altering the reactivity of either functional group.

Brian S. Haynes - One of the best experts on this subject based on the ideXlab platform.

  • Oxyreactivity of Carbon Surface oxides
    Proceedings of the Combustion Institute, 2000
    Co-Authors: Brian S. Haynes, Timothy G. Newbury
    Abstract:

    The behavior of Carbon Surface oxides formed in 18O2 and exposed subsequently to 16O2 has been studied by mass spectrometric determination of the gaseous products which include all the possible isotopic forms of CO and CO2. In addition, the oxides remaining on the Surface of the Carbon have been characterized by temperature-programmed desorption (TPD) to yield CO. The experiments were conducted at a total pressure of 2.7 Pa at temperatures of 873, 973, and 1073 K. Both the transient kinetic experiments and the TPD studies point to the occurrence of a reaction between Surface-bound oxides and gas-phase oxygen to gasify Carbon and at the same time create new Surface oxide. The overall reaction proceeds as C(18O)+16O2→C(16O)+C18O, C16O18O (R3) but the precise stoichiometry remains unknown. The kinetics of reaction R3 have been studied as a function of the characteristic energy for decomposition of the Surface complexes (Edes), in the range 280 The contribution of reaction R3 to the overall rate of gasification of the Carbon under the experimental conditions ranges from 45% at 873 to 4% at 1073 K.

  • Interaction of Carbon monoxide with Carbon and Carbon Surface oxides
    Energy & Fuels, 1992
    Co-Authors: T. C. Brown, Brian S. Haynes
    Abstract:

    The Surface complexes formed when Spherocarb is exposed to CO have been investigated over a wide range of temperatures (420-970 K) and CO pressures (0.2-8.0 kPa) using thermogravimetry and a mass-spectral analysis of evolved gases. Relative to oxygen, Carbon monoxide has only a limited propensity to chemisorb to a Carbon Surface and the nature of the complexes formed in the two systems is also different, as evidenced by their distinct TPD patterns

Xinxing Liang - One of the best experts on this subject based on the ideXlab platform.

  • Study of Carbon Surface-modified Li[Li0.2Mn0.54Ni0.13Co0.13]O2 for high-capacity lithium ion battery cathode
    Journal of Solid State Electrochemistry, 2012
    Co-Authors: Yun-hua Deng, Suqin Liu, Xinxing Liang
    Abstract:

    Carbon Surface-modified Li-excess layered oxide solid solution Li[Li0.2Mn0.54Ni0.13Co0.13]O2 cathode is fabricated through a liquid phase route using polyvinylpyrrolidone as Carbon source. X-ray diffraction and X-ray photoelectron spectroscopy indicate that the crystal structure and the chemical states of elements for Li[Li0.2Mn0.54Ni0.13Co0.13]O2 are kept after Carbon Surface treatment. The high-resolution transmission electron microscopy demonstrated the existence of very little Carbon on the Surface and the clear boundary after Carbon treatment. The Carbon Surface-modified sample delivers a discharge capacity of 293.2 mAh g−1 at C/10 rate (suppose 1 C rate = 250 mA g−1) and 191.6 mAh g−1 at 1 C rate between 2.0 and 4.8 V; the capacity retention rate is ∼86 % after 70 cycles at 1 C rate. Superior electrochemical properties can be contributed to the Carbon Surface modification in these aspects including minimizing nanoparticle aggregation and cell polarization, increasing the electronic conductivity, suppressing the elimination of oxide ion vacancies, as well as suppressing the formation of the thick solid electrolyte interfacial layer. Moreover, the annealing process of Carbon Surface modification might be able to consume Li2CO3 impurity partly and cause the recrystallization of the Surface disordered layer.