Double capacity

Gouy-Chapman capacity - double layer, -> Parsons and Zobel Plot... 

Q. Y. Wang, J. Liu, A. V. Murugan, A. Manthiram, High capacity double-layer surface modified Li[Li0.2Mn0.54Ni0.13Co0.13]02 cathode with improved rate capability, J. Mater. Chem. 2009,19,4965-4972. 

Homogeneous propellants are either simple base or double base. A simple base propellant consists of a single compound, usually nitrocellulose, which has both an oxidation capacity and a reduction capacity. Double base propellants usually consist of nitrocellulose and nitroglycerine, to which a plasticizer is added. Homogeneous propellants do not usually have specific impulses greater than about 210 seconds under normal conditions. Their main asset is that they do not produce traceable fumes and are, therefore, commonly used in tactical weapons. 

Molinard pointed out that the ions introduced can serve as specific adsorption sites and that this type of modification allows fine-tuning of the PILC substrate for certain gas adsorption applications [18]. By introducing Sr + in Al-PILC, the gas adsorption isotherms at 273 K and 5 x 10 Pa equilibrium pressure showed that the Nj capacity doubled fi-om 0.06 nunol/g on Al-PILC to 0.12 mmol/g on Sr-Al-PILC. The amoimt of cations in the PILC influences the adsorption properties. A higher cation loading results in a lower capacity but a higher N2/O2 selectivity on Ca-Al-PILC, as was proven by adsorption measurements. For the anion exchanged Cl-Al-PILC, more O2 than N2 was adsorbed (0.09 mmol/g and 0.07 mmol/g, respectively) at 273 K and 5x10 Pa. This affinity for O2 should result from a specific interaction with the Cl"-ions. The CO2 capacity decreased in comparison with the unmodified substrate from 0.5 mmol/g on Al-PILC to 0.2 mmol/g on Cl-Al-PILC at 273 K and 0.5 bar. After modification with other anions, Hke F and PO, the same effect was observed. 

This method follows the ASTM D 1159 and D 2710 procedures and the AFNOR M 07-017 standard. It exploits the capacity of the double olefinic bond to attach two bromine atoms by the addition reaction. Expressed as grams of fixed bromine per hundred grams of sample, the bromine number, BrN, enables the calculation of olefinic hydrocarbons to be made if the average molecular weight of a sufficiently narrow cut is known. 

By analogy with the Helmholtz condenser formula, for small potentials the diffuse double layer can be likened to an electrical condenser of plate distance /k. For larger yo values, however, a increases more than linearly with o, and the capacity of the double layer also begins to increase. 

The shape of the electrocapillary curve is easily calculated if it is assumed that the double layer acts as a condenser of constant capacity C. In this case, double integration of Eq. V-50 gives... 

Fig. V-12. Variation of the integral capacity of the double layer with potential for 1 N sodium sulfate , from differential capacity measurements 0, from the electrocapillary curves O, from direct measurements. (From Ref. 113.)...

Derive the general equation for the differential capacity of the diffuse double layer from the Gouy-Chapman equations. Make a plot of surface charge density tr versus this capacity. Show under what conditions your expressions reduce to the simple Helmholtz formula of Eq. V-17. 

Owing to the corrosive action of bromine upon corks j-jg 7, l. and rubber stoppers, ground glass joints are recommended in this preparation. The apparatus, depicted in Fig. Ill, 37, 1, is particularly convenient for the preparation of bromides from alcohols. A double surface condenser is fitted into D and a round-bottomed flask is fitted on to the ground glass joint at C R is a three-way stopcock f which permits the removal of the contents of A without disconnecting the apparatus. For preparations of moderate size, A has a capacity of 60 or 100 ml. and a 250 or 500 ml. flask is attached at C. 

Any improvement in resolution obtained by increasing ki generally comes at the expense of a longer analysis time. This is also indicated in Figure 12.11, which shows the relative change in retention time as a function of the new capacity factor. Note that a minimum in the retention time curve occurs when b is equal to 2, and that retention time increases in either direction. Increasing b from 2 to 10, for example, approximately doubles solute B s retention time. 

If the capacity factor and a are known, then equation 12.21 can be used to calculate the number of theoretical plates needed to achieve a desired resolution (Table 12.1). For example, given a = 1.05 and kg = 2.0, a resolution of 1.25 requires approximately 24,800 theoretical plates. If the column only provides 12,400 plates, half of what is needed, then the separation is not possible. How can the number of theoretical plates be doubled The easiest way is to double the length of the column however, this also requires a doubling of the analysis time. A more desirable approach is to cut the height of a theoretical plate in half, providing the desired resolution without changing the analysis time. Even better, if H can be decreased by more than... 

The fundamental case for pressure filters may be made using equation 10 for dry cake production capacity Y (kg/m s) derived from Darcy s law when the filter medium resistance is neglected. Eor the same cycle time (same speed), if the pressure drop is increased by a factor of four, production capacity is doubled. In other words, filtration area can be halved for the same capacity but only if is constant. If increases with pressure drop, and depending how fast it increases, the increased pressure drop may not give much more capacity and may actually cause capacity reductions. 

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