Browsing by Subject "Precipitation"

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    Effect of the polarity of solvents on periodic precipitation: Formation of hierarchical revert liesegang patterns
    (American Chemical Society, 2022-10-11) Holló, Gábor; Zámbó, Dániel; Deák, András; Rossi, Federico; Rossi, Federico; Cucciniello, Raffaele; Nostro, Pierandrea Lo; Nabika, Hideki; Baytekin, Bilge; Lagz, István; Itatani, Masaki
    Liesegang pattern (LP) is one example of self-organized periodic precipitation patterns in nonequilibrium systems. Several studies have demonstrated that the LP morphology can track physicochemical environmental conditions (e.g., temperature); however, the polarity effect has not been explored to date. In this study, a copper chromate system is used to reveal the impact of solvent polarity on the evolving LP structure using water/organic solvent mixtures. In the typical case of using water/dimethyl sulfoxide (DMSO) mixtures, two drastic changes in LP morphology with increasing DMSO contents were found: (i) increasing frequency of the original structure and (ii) formation of a hierarchical pattern with the appearance of another, lower-frequency structure. Furthermore, the simulation model operating with a bimodal size distribution, allowing both homogeneous and heterogeneous precipitations showed good agreement with the experimental results. Therefore, this study demonstrated that LP can be tailored by solvent polarity and can be used for designing hierarchical precipitation patterns in a straightforward manner.
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    ItemOpen Access
    Sorption studies of Cs+, Ba2+, and Co2+ ions on bentonite using radiotracer, ToF-SIMS, and XRD techniques
    (De Gruyter Oldenbourg, 2001) Shahwan, T.; Erten H. N.
    The sorption behaviour of Cs+, Ba2+, and Co2+ ions on bentonite were investigated using the radiotracer method, Time of Flight-Secondary Ion Mass Spectroscopy (ToF-SIMS), and X-Ray Diffraction (XRD). The sorption of Cs+ and Ba2+ were exothermic while sorption of Co2+ was endothermic. The sorption data were well described by Freundlich and Dubinin-Radushkevich isotherms. According to ToF-SIMS results Na+ and Mg2+ were the primary exchanging ions in bentonite. The XRD spectra showed that no structural changes were associated with the sorption of Cs+ and Co2+, and BaCO3 precipitate was formed upon the sorption of Ba2+ on bentonite.