Carbon Dioxide Capture by Adsorption in a Model Hydroxy-Modified Graphene Pore.

Concerns regarding the environmental impact of increasing levels of anthropogenic carbon dioxide have led to a variety of studies examining solid surfaces for their ability to trap this greenhouse gas (GHG). Atmospheric or post-combustion carbon capture requires an efficient separation of carbon dioxide and nitrogen gas. We used the molecular mechanics MM3 parameter set (previously shown to provide good estimates of molecule-surface binding energies) to calculate theoretical surface binding energies for carbon dioxide ∆E(CO) and nitrogen ∆E(N).

Teslaphoresis of Carbon Nanotubes.

This paper introduces Teslaphoresis, the directed motion and self-assembly of matter by a Tesla coil, and studies this electrokinetic phenomenon using single-walled carbon nanotubes (CNTs). Conventional directed self-assembly of matter using electric fields has been restricted to small scale structures, but with Teslaphoresis, we exceed this limitation by using the Tesla coil's antenna to create a gradient high-voltage force field that projects into free space. CNTs placed within the Teslaphoretic (TEP) field polarize and self-assemble into wires that span from the nanoscale to the macroscale, the longest thus far being 15 cm.

Comparison of gas-solid chromatography and MM2 force field molecular binding energies for greenhouse gases on a carbonaceous surface.

Gas-solid chromatography was used to determine B(2s) (gas-solid virial coefficient) values for eight molecular adsorbates interacting with a carbon powder (Carbopack B, Supelco). B(2s) values were determined by multiple size variant injections within the temperature range of 313-553 K. The molecular adsorbates included: carbon dioxide (CO(2)); tetrafluoromethane (CF(4)); hexafluoroethane (C(2)F(6)); 1,1-difluoroethane (C(2)H(4)F(2)); 1-chloro-1,1-difluoroethane (C(2)H(3)ClF(2)); dichlorodifluoromethane (CCl(2)F(2)); trichlorofluoromethane (CCl(3)F); and 1,1,1-trichloroethane (C(2)H(3)Cl(3)).

Binding energies for alkane molecules on a carbon surface from gas-solid chromatography and molecular mechanics.

Gas-solid chromatography was used to determine B(2s) (gas-solid virial coefficient) values for 12 alkanes (10 branched and 2 cyclic) interacting with a carbon powder (Carbopack B, Supelco). B(2s) values were determined by multiple size variant injections within the temperature range of 393 to 623 K with each alkane measured at 5 or 6 different temperatures. The temperature variations of the gas-solid virial coefficients were used to find the experimental adsorption energy or binding energy values (E( *)) for each alkane.

Evaluation of molecular mechanics calculated binding energies for isolated and monolayer organic molecules on graphite.

The calculated molecule-surface binding energy, E(cal)( *), for physical adsorption was determined using molecular mechanics MM2 parameters for a model graphite surface and various organic molecules. The results for E(cal)( *) were compared to published experimental binding energy values, E( *), from gas chromatography (GC) or thermal desorption (TD). The binding energies from GC were for isolated molecules in the Henry's law region of adsorption, and the binding energies from TD were for molecules in monolayer coverage on a highly oriented pyrolytic graphite (HOPG).

Determining molecule-carbon surface adsorption energies using molecular mechanics and graphene nanostructures.

Five model surfaces were developed using molecular mechanics with MM2 parameters. A smooth, flat model surface was constructed of three parallel graphene layers where each graphene layer contained 127 interconnected benzene rings. Four rough surfaces were constructed by varying the separation between a pair of graphene nanostructures placed on the topmost layer of graphene.

Adsorption energies for a nanoporous carbon from gas-solid chromatography and molecular mechanics.

Gas-solid chromatography was used to obtain second gas-solid virial coefficients, B2s, in the temperature range 342-613 K for methane, ethane, propane, butane, 2-methylpropane, chloromethane, chlorodifluoromethane, dichloromethane, and dichlorodifluoromethane. The adsorbent used was Carbosieve S-III (Supelco), a carbon powder with fairly uniform, predominately 0.55 nm slit width pores and a N2 BET surface area of 995 m2/g.

Predicting second gas-solid virial coefficients using calculated molecular properties on various carbon surfaces.

Gas-solid chromatography was used to obtain values of the second gas-solid virial coefficient, B2s, in the temperature range from 343 to 493 K for seven adsorbate gases: methane, ethane, propane, chloromethane, chlorodifluoromethane, dimethyl ether, and sulfur hexafluoride. Carboxen-1000, a 1200 m2/g carbon molecular sieve (Supelco Inc.), was used as the adsorbent.

Molar Refractivity and Connectivity Index Correlations for Henry's Law Virial Coefficients of Odorous Sulfur Compounds on Carbon and for Gas-Chromatographic Retention Indices.

Gas-solid chromatography was used to obtain values of the second gas-solid virial coefficient, B(2s), in the temperature range from 392 to 511 K for 10 volatile, malodorous organic sulfur compounds; ethanethiol, 1-propanethiol, methyl sulfide, 2-propanethiol, 1-methyl-1-propanethiol, 2-methyl-1-propanethiol, 2-methyl-2-propanethiol, ethyl sulfide, ethyl methyl sulfide, and tert-butyl methyl sulfide. Carbopack C (Supelco Inc.), a graphitized carbon black powder, was used as the adsorbent.