Surface Properties Of Mnco3: Adsorption
Surface Properties of MnCO3: Adsorption
of the Organic Compounds from Water Solution
N.V. Nikolenko
Ukrainian State Chemical Technology University,
Gagarin av. 8, 49005 Dniepropetrovsk, Ukraine, e-mail: nick@academy.dp.ua
Surface properties of manganese (II) carbonate are of interest in connection with flotation problems of carbonaceous minerals. It is known that for the adsorption of polar molecules on ionic adsorbents, the contribution of dispersion and electrostatic forces is most significant. We believe that the selectivity of adsorption can be explained also as the property which arises due to the chemisorption interactions. The result of chemical interaction can be estimated from SCF MO calculations if the system is simple enough. For a complicated system, in particular, the solid surface, the perturbation MO theory can be used, which is capable for the visualizing of many factors which are responsible for the chemical bonding phenomena.
In this study, the vertical potentials of ionization, energies of vertical electronic transferring and effective charges of atoms are used as the parameters of correlation between electronic and adsorptive properties of substance. The adsorption of more than 20 aromatic and heterocyclic nitrogen- and oxygen-containing hydrocarbons from water solutions onto MnCO3 surface in static conditions was studied. To identify chemisorption interactions, the electronic spectra of adsorbed compounds were employed.
The model for the description of the chemisorption of polar molecules at MnCO3 surface is proposed, developed on the basis of adsorptive and UV-spectroscopic data. The model involves three types of interactions: 1, 2 and 3-electron donor-acceptor interaction between HOMO and LUMO of adsorbate and adsorbent. The obtained results allow assuming that the adsorption of polar organic compounds from water solutions on MnCO3 is caused by weak chemical interaction. In formation of surface bonds participate electrons both heteroatoms and aromatic rings of the molecules.
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