The effect of the physical and chemical characteristics of activated carbons on the adsorption energy and affinity coefficient of Dubinin equation

The dependency of adsorption energy (E) and affinity coefficient (beta) of Dubinin equations (Dubinin-Radushkevich (DR) or Dubinin-Astakhov (DA)) on surface chemistry and porosity of activated carbons was investigated by analyzing adsorption of nitrogen, benzene, trichloroethylene (TCE), and water vapor by several surface-modified activated carbons and carbon fibers. For all studied nonpolar adsorbates, carbons with smaller average micropores showed higher adsorption energies independent of their surface chemistry. For water vapor, carbons with higher surface polarities showed higher adsorption energies due to specific adsorbate-adsorbent interactions. Adsorption energies increased with decreasing average micropore widths. betaN2,DR for different carbons were observed to vary in the 0.292-0.539 range. Carbons with higher degrees of mesoporosity had higher betaN2,DR values, while no dependency was observed between betaN2,DR and surface chemistry. A comparison of DR and DA cases indicates that: (1) the average value of betaN2,DA is considerably above the classical value of this parameter; and (2) the range of betaN2,DA values were smaller compared to betaN2,DR, despite a wide range of mesoporosity of carbons examined. Obtained beta(TCE,DR) values varied in the 0.952-1.243 range, with an average value of 1.085+/-0.083, independent of surface chemistry or porosity of activated carbons. A similar result was observed for beta(TCE,DA). betaH2O,DR values of different granular and fibrous activated carbons changed in the range of 0.081-0.271. They depended more on the carbon surface chemistry and less on the porosity. A similar result was obtained when DA equation was considered.     

A digital pseudo-random number generator based on sawtooth chaotic map with a guaranteed enhanced period

Nonlinear Dynamics - We investigate tunneling behavior between two bright solitons in a Bose–Einstein condensate with attractive contact interactions between atoms. The explicit tunneling...     

Heavily doped Si:P emitters of crystalline Si solar cells: recombination due to phosphorus precipitation

The measured saturation current density J_0e of heavily phosphorus‐doped emitters of crystalline Si solar cells is analysed by means of sophisticated numerical device modelling. It is concluded that Shockley–Read–Hall (SRH) recombination exceeds Auger recombination significantly; it is caused by inactive phosphorus. This explains the large discrepancies between measured and simulated J_0e values, observed persist‐ently over the last two decades in industrially fabricated Si solar cells. As a consequence, the heavily phosphorus‐diffused emitters still bear a significant potential to contribute to higher Si solar cell efficiency levels, if the amount of inactive phosphorus can be reduced. (© 2014 WILEY‐VCH Verlag GmbH &Co. KGaA, Weinheim)