Interpretation of the adsorption of metals on quartz crystal based-macromolecule via advanced modeling of equilibrium isotherms

In this article, new insights about the metals-porphyrin complexes are proved by analyzing the zinc, nickel and chromium adsorption process over the well-known porphyrin macromolecule. The use of the quartz crystal microbalance (QCM) apparatus allows the control of the complexation systems’ experimental adsorption data operating at four temperatures. The experimental results and the physical models reveal that the zinc and nickel complexation processes are to be examined using the mono layer adsorption model. While, the double layer model describes the interaction between the chromium compound and the porphyrin. Actually, the three metals are shown to be adsorbed by a multi-docking process in the physicochemical description. The endothermic character of the investigated processes is shown through the appropriate data of the principal parameter adsorbent sites’ density. Hence, several porphyrin sites are exclusively stimulated at high temperature. The parameters of van del Waals, depicting the influences of the lateral interactions, explain the nickel isotherms down trend. The chemical bonds are shown to be carried out between the zinc and the porphyrin through the calculated adsorption energies. Considering the thermodynamic study, and referring to the configurational entropy and the free enthalpy, it is to be noted that the disorder peak of the three mechanisms is reached when the equilibrium concentration is equal to the energetic parameters’ values for each system. The nickel enthalpy revealed for high concentration that the adsorbates’ lateral interactions disapproved the nickel chloride adsorption. The free enthalpy trends, that observed two stability states of the chromium compound, confirmed the chromium double layer mechanism.

Ca10(CrVO4)6(CrVIO4), a disordered mixed-valence chromium compound exhibiting inversion twinning

The structure analysis of so-called 9CaO·4CrO3·Cr2O3proved it to be the title compound, decacalcium hexakis[chromate(V)] chromate(VI), with the simultaneous presence of unusual chromium oxidation states. The structure determination was carried out on a crystal that had inversion twinning. The CrVIO4tetrahedron is situated on a threefold axis and is disordered over two possible orientations that share three O atoms, while the CrVO4tetrahedra are in general positions and are ordered. The charge is balanced by Ca2+cations, one of which is located on a threefold axis. The Ca2+ions are coordinated by six, seven or eight O atoms. The compound is a significant phase in the CaO–CrOxsystem and its formation reduces the refractoriness of calcium-rich compositions in an oxidizing atmosphere.

FT RAMAN AND FTIR SPECTRA OF FOUR DISELENITES PbSe2O5, CdSe2O5, MnSe2O5 and Cr2(Se2O5)3

The vibrational spectra of Lead diselenite, Cadmium diselenite, Manganese diselenite and chromium diselenite have been recorded and analysed on the basis of vibrations due to [Formula: see text] ion. The observed spectra clearly indicate the presence of diselenite group in all these compounds. The spectral analysis confirms the orthorhombic nature of MnSe 2 O 5 as suggested by Koskenlinna et al. A large number of vibrational bands in the symmetric stretching region of PhSe 2 O 5 is due to the existence of different Se-O bond lengths. From the spectra it can be seen that the anion is highly distorted angularly in chromium compound. This high distortion in all modes confirms the presence of three crystallographically distinct diselenite groups in chromium compound.