The Study of Adsorption of Iodine on Carbon Black by Inverse Liquid Chromatography

The study of iodine adsorption on carbon black samples was made using inverse liquid chromatographic frontal analysis (ILC). Unlike HPLC supports, the efficiency of the chromatographic column filled with a carbon black designed for rubber applications is low. Then the front boundaries of a non-adsorbed molecule, like heavy water (D2O) or acetone, was taken as reference for the calculation of the desorption isotherms. The monolayer capacity of adsorption, Langmuir's and Henry's constants were determined from the desorption isotherms. It was observed that 40% of the surface of the studied carbon black corresponds to a phenomenon of irreversible adsorption of the probe, and that the ILC also highlighted the heterogeneity of the studied carbon black. The adsorption energy distribution functions of iodine obtained by this method are similar to those which were already determined by IGC-FC with the heptane -like probe. The differences in behaviors between two families of carbon black could be attributed to the surface roughness.

Heterogeneous Adsorption of Activated Carbon Nanofibers Synthesized by Electrospinning Polyacrylonitrile Solution

This study focuses on the adsorption properties of activated carbon nanofibers (CNFs) fabricated by electrospinning polyacrylonitrile solutions dissolved in dimethylformamide, followed by heat treatment at high activation temperatures (700, 750, 800 °C). The samples were characterized by BET, SEM, and XRD. In addition, the adsorption energy distribution functions of CNFs were analyzed by using the generalized nonlinear regularization method. Comparative analysis of energy distribution functions provided significant information on the energetic and structural heterogeneities of CNFs. Furthermore, an investigation of adsorption equilibrium and kinetics of methylene blue (MB) and congo red (CR) revealed that the adsorption capacity and kinetics of MB are much higher and faster than that of CR on a given sample. Our experimental and theoretical results suggest that the CNFs used in this work may be widely used as an adsorbent.

Changes of mineralogical and surface properties of water dispersible clay after acid treatment of soils

Mineralogical and water adsorption properties of water dispersible clays extracted from five soils of different typology after treatment with acid to different pH levels, were studied. The mineral composition, total and divalent iron content, surface areas and average adsorption energies of water dispersible clays were complicated functions of pH, reflecting the simultaneous effects of mineral destruction and aggregate disruption processes under influence of protons on soils. The magnetic susceptibilities of water dispersible clays were the lowest at pH 2 and roughly constant at higher pH values indicating the dissolution of crystalline forms of Fe below pH 3. The broadening of the peaks of adsorption energy distribution functions with decrease in pH is related to increasing formation of amorphous material from mineral phases.

Physical adsorption of CO2 on graphite: monolayer and multilayer regions

Different models which describe CO2 physisorption on a graphitized carbon black are analysed in the range 194·7 to 273·2 K. They are related to the thermodynamic functions and to adsorption energy distribution functions, which are obtained starting from experimental adsorption isotherms. This calculation, previously presented, is based on an extension of the Ross and Olivier method.