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The biomimetic synthesis and phase transformation of XRD amorphous calcium phosphate were studied by application of kinetic, chemical and spectral (XRD and IR) methods and thermodynamic simulations. Two SBFs (SBFc and SBFr), differing in their HCO(3)(-) and Cl(-) ion contents, were used in the maturation studies. It has been proven that the biomimetic maturation accelerated the phase transformation of less thermodynamically stable amorphous calcium phosphate to poorly crystalline hydroxyapatite. Several regularities have been found: (i) kinetic reasons determined the biomimetic precipitation of XRD-amorphous calcium deficient phosphate (ACP); (ii) the precipitated ACP always contained impurities due to co-precipitation, ion substitution and incorporation phenomena; (iii) the increased content of HCO(3)(-) ions in the surrounding microenvironments increased the rate of phase transformation and the concentration of MeHCO(3)(+) (Me = Ca, Mg) species in the solution, but the solubility of CaCO(3) has only been decreased and its precipitation accelerated, thus playing a crucial role in the process under study.

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The main goal of this presentation is to tentatively forecast or improve an extractive process. The sea-water system is described using a graphical representation of the quinary ion-pair system Na+, K+, Mg2+/Cl−, SO42-//H2O. The operations required by extraction or purification of a sea-water component are simulated by a path through the solubility diagram.The procedure is applied to isothermal evaporation of Black Sea water at 25 °C, and the balance of the crystallization sequence is determined. In the same way, the cooling of residual brine, after precipitation of pure sodium chloride, is studied.

The inorganic chemical species in Maresh and Luda Yana rivers affected by the Cu- Mo Asarel-Medet mine, Bulgaria were determined during a low-flow and a high-flow period. The mining activities, the weathering and the oxidation processes strongly influenced the physicochemical processes in the whole water system. The main pollution source was a small lake receiving the acid effluents of the mining activities. High levels of SO4(2-), Cu, Mg, Al, Mn and Fe were determined at the mining polluted and affected stations. Cu(2+) and CuCO3(0) species (1:1) were present in the reference waters and Cu(2+) and CuSO4(0) species (1:1) in the polluted and affected waters; Cu(2+) species was dominating downstream. Me(2+) followed by MeSO4(0) (Me = Mn, Zn, Cd and Pb), PbCO3(0) and PbHCO3(+) species as well as Fe(OH)2(+), Al(OH)4(-), Al(OH)2(+), Al(OH)3(0) were prevailing in the system. MeSO4(+) and Me(SO4)2(-) (Me = Fe, Al), Me(SO4)2(2-) (Me = Zn, Cd and Pb), Me(SO4)3(4-) (Me = Zn, Cd) and Cd(SO4)4(6-) species polluted and affected waters. The major elements K and Na were mainly Me(+) species, whereas Ca and Mg were Me(2+) and MeSO4(0) species in different ratios. The concentration of concentration of NO2(-), NO3(-) and NO4(+) species as well as complex phosphorous species such as H2PO4(-), FeHPO4(+), HPO4(2-), CaPO4(-), CaHPO4(0) and MgHPO4(0) were also calculated. The trace element concentrations decreased downstream due to dilution, sorption processes and precipitation, but the percentage of free metal species, which are more toxic, increased. An exception was iron and aluminum of which the dominant hydroxy colloidal and sulphate species were easily incorporated into the suspended phase.

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