A statlc, volumetrlc method has been used to determine the adsorptlon equlllbrla of C2H4, C,H6, I-C4Hlo, and CO, and thelr blnary mlxtures on 13X molecular sleves at varlous temperatures between 273 and 373 K. Pressures for the puretomponent data extend up to 137.8 kPa, whlle all blnary data were obtalned at 137.8 kPa. The I-C4Hlo-C,H, system at 298 and 323 K and the C2H4-C02 system at 298 K were found to be highly nonldeal In their behavlor-they exhlblt adsorptlon azeotropes. Methods for predlctlng gas-mlxture adsorptlon data from the pure-component Isotherms were evaluated. Only the vacancy solutlon model was able to predlct the areotroplc behavlor even qualltatlvely. I ntroductlonGas adsorption on sdid surfaces is an important unit operation for the separation of gases. The technology of adsorption, however, is less advanced than that of other common separation processes such as distillation, extraction, and absorption. The complexity of adsorption phenomena and the lack of accurate and complete experimental adsorption data have been major factors in inhibiting developments in adsorption technology.Molecular sieves (zeolites) have been widely used as adsorbents because of their selectivity, adsorption capacity, and thermal and chemical stability. I n practice, adsorption processing involves the treatment of multicomponent mixtures. Very few experimental data are available for adsorption systems which exhibit highly nonideal behavior. The systems reported in this paper are quite nonideal-they have adsorption azeotropes. Thus, they should be quite useful for evaluating and developing adsorption equilibrium models. Three such models are evaluated herein. Experlmental SectionApparatus. The apparatus was of the volumetric type and used the difference technique for determining adsorbed-phase compositions. The total quantity of each gas admitted to the adsorbent and the amount of each gas remaining in the vapor phase after adsorption equilibrium had been established were determined by P -V -T measurements, and an analysis of the remaining vapor phase was determined by gas chromatography. The adsorbed-phase parameters were then determined by the difference between the quantities of admitted and remaining gases. Details of the equipment and the operating procedure are described in the paper by Dorfman and Danner (1).Maferlals. The adsorbent was molecular sieve type 13X in the form of '/i6-in. pellets manufactured by the Linde Division of Union Carbide (Lot No. 13945390174). This sieve contained 20% by weight of an inert clay as a binding material. The unit cells of 13X molecular sieve are cubic with a large cell dimension of nearly 25 A. The pore volume as determined by adsorption from n-pentane at 25 OC by Breck (2) is about 0.3 cm3/g. The surface area determined by the BET method using nitroqen at 77 K is 525 m2/g (2). For the pellets used in this 0021-9568/82/ 1727-0196$01.25/0 study, these values had to be decreased by 20% to account for the inert binder. A differential thermal analysis of the adsorbent indicated t...

A colloidal suspension of exfoliated, layered cobalt oxide nanosheets has been synthesized through the intercalation of quaternary tetramethylammonium ions into protonated lithium cobalt oxide. According to atomic force microscopy, exfoliated nanosheets of layered cobalt oxide show a plateau-like height profile with nanometer-level height, underscoring the formation of unilamellar 2D nanosheets. The exfoliation of layered cobalt oxide was cross-confirmed by X-ray diffraction, UV/Vis spectroscopy, and transmission electron microscopy. The maintenance of the hexagonal in-plane structure of the cobalt oxide lattice after the exfoliation process was evidenced by selected-area electron diffraction and Co K-edge X-ray absorption near-edge structure analysis. The zeta-potential measurements clearly demonstrated the negative surface charge of cobalt oxide nanosheets. Adopting the nanosheets of layered cobalt oxide as a precursor, we were able to prepare the monodisperse CoO nanocrystals with a particle size of approximately 10 nm as well as the heterolayered film composed of cobalt oxide monolayer and polycation.

We construct a quasi-local formalism for conserved charges in a theory of gravity in the presence of matter fields which may have slow falloff behaviors at the asymptotic infinity. This construction depends only on equations of motion and so it is irrespective of ambiguities in the total derivatives of the Lagrangian. By using identically conserved currents, we show that this formalism leads to the same expressions of conserved charges as those in the covariant phase space approach. At the boundary of the asymptotic AdS space, we also introduce an identically conserved boundary current which has the same structure as the bulk current and then show that this boundary current gives us the holographic conserved charges identical with those from the boundary stress tensor method. In our quasi-local formalism we present a general proof that conserved charges from the bulk potential are identical with those from the boundary current. Our results can be regarded as the extension of the existing results on the equivalence of conserved charges by the covariant phase space approach and by the boundary stress tensor method. *

We construct IIA GS superstring action on the ten-dimensional pp-wave background, which arises as the compactification of eleven-dimensional pp-wave geometry along the isometry direction. The background geometry has 24 Killing spinors and among them, 16 components correspond to the non-linearly realized kinematical supersymmetry in the string action. The remaining eight components are linearly realized and shown to be independent of x + coordinate, which is identified with the world-sheet time coordinate of the string action in the light-cone gauge. The resultant dynamical N =(4,4) supersymmetry is investigated, which is shown to be consistent with the field contents of the action containing two free massive supermultiplets.

No abstract