Small molecule substances as molecular probes of structure and texture of coal under sorption process and modelling

Multiple Sorption Model (MSM) is used to simulate sorption isotherms and the effect of the multiplicity of physicochemical parameters is reduced by introducing an invariant procedure using a few sorbates that are small molecules. This study presents the use of water, methanol, carbon dioxide and methane as test molecules to determine the structure and texture of coal and energy parameters. Parallel calculations for a set of sorption systems on the same coal sample recursively yield the most probable estimates. The procedure was tested for 6 coal samples with different carbon content. Effect of simulations made by MSM is evaluated on measurements of sorption isotherms. Result obtained by the analysis shows that smaller submicropores are in better contact with sorbate molecule and bigger one contact is weaker-contacts play vital role in energy contribution to the molecule. Tendency of significant absorption for CO2 and CH3OH and insignificant for H2O and CH4 is confirmed on the basis of thermodynamic dissertation/calculation.

Study of Sorption of Triphenylmethane Dyes on a Magnetic Carrier Bearing an Immobilized Copper Phthalocyanine Dye

Magnetite particles bearing covalently immobilized copper phthalocyanine dye ("blue magnetite") were prepared and used for the sorption of triphenylmethane dyes from aqueous solutions. The binding of some triphenylmethane dyes bearing two or three amino groups (basic fuchsin, crystal violet, malachite green) followed the Langmuir adsorption model. The maximum adsorption capacities were calculated. Dyes having no amino group in their molecules exhibited only low adsorption to immobilized copper phthalocyanine. The presence of amino groups in the molecules of triphenylmethane dyes seems to be necessary for their efficient binding on blue magnetite. Generally, efficient sorption of the organic compounds to immobilized copper phthalocyanine may be conditional on a cooperative effect of two parameters, viz. a certain planarity of the sorbate molecule and interaction of the central copper ion of the phthalocyanine molecule with the sorbate amino group or heterocyclic nitrogen atom.

Free Energies of Adsorption of Dipeptides and 2,5-Piperazinediones on Silica from Neutral Aqueous Solutions as Estimated from High-Performance Liquid-Chromatographic Retention Data

The equilibrium constants (K) and free energies (-∆G) of adsorption of dipeptides and their cyclic derivatives, 2,5-piperazinediones, on silica from neutral aqueous solutions were calculated from their HPLC retention data on a silica gel column. For the majority of the dipeptides -∆G values were negative, ranging from -1 170 to 430 J mol-1, and K < 1, thus indicating a very weak adsorption. The 2,5-piperazinediones under study exhibited higher adsorbabilities (-∆G -1 070 + 3 030 J mol-1, K > 1) as compared to the respective dipeptides. The effect of the α-substituent structure on the adsorbability is analyzed. A linear dependence of -∆G on the number of aliphatic carbon atoms in a sorbate molecule was observed for the series of dipeptides and 2,5-piperazinediones derived from bifunctional aliphatic amino acids.