Authors:J. Yao, Y. Liu, Z. Gao, P. Liu, M. Sun, S. Qu, and Z. Yu
A microcalorimetric technique based on the bacterial heat-output was explored to evaluate the effect of Mn(II) on Bacillus thuringiensis. The power-time curves of the growth metabolism of B. thuringiensis and the effect of Mn(II) on it were studied using an LKB-2277 BioActivity Monitor, ampoules method, at 28C. For evaluation
of the results, the maximum peak-heat output power (Pmax) in the growth phase, the growth rate constants (k), the log phase heat effects (Qlog ), and the total heat effect in 23 h (QT) for B. thuringiensis were determined. Manganese has been regarded as the essential biological trace element. Mn(II) of different concentration
have different effects on B. thuringiensis growth metabolism. High concentration (800-1600 μg mL-1) of Mn(II) can promote the growth of B. thuringiensis; low concentration (500-800 μg mL-1) can inhabit its growth.
A radiochemical solvent extraction method has been developed for the determination of Mn(II) using54Mn tracer. Mn(II) is complexed with 2-thenoyltrifluoroacetone (TTA) at pH 8.5 and extracted in isobutyl methyl ketone (IBMK). Different parameters affecting the extraction, and interferences due to diverse ions have been studied. The method can be used for the determination of Mn in microgram amounts.
this study was to obtain the complexes of Mn(II), Co(II), Ni(II), Cu(II) and Zn(II) with 3-(anilinomethylene)-2-methoxychroman-4-one and to determine their properties. The thermal behaviour of these compounds was investigated by using thermogravimetric
Authors:M. Gaber, G. B. El-Hefnawy, M. A. El-Borai, and N. F. Mohamed
of metal complexes [ 30 – 36 ].
In this study, we described the synthesis and characterization of Mn(II), Co(II), Ni(II) Cu(II) and Zn(II) complexes with azodyes derived from 8-hydroxyquinoline and anthranilic acid or o -aminophenol. The
A rapid method has been described for the quantitative extraction of milligram amounts of Mn/II/ with 2-PRONAPOX into CHCl3. The extraction coefficient /E/ of Mn/II/ between CHCl3 and aqueous solution containing 0.2M NH4Cl shows a maximum value of E=143 at pH 10.5. The percentage extraction is better than 98% in the pH range from 9 to 11 and an equilibration time of 6 min. The effects of anions and cations have been studied. The stoichiometry of metal: reagent determined by substoichiometric extraction and slope ratio method is found to be 12. The decontamination factors for most of the elements are better than 104 in the substoichiometric extraction of Mn/II/.
Authors:A. I. El-Said, A. A. M. Aly, and A. S. A. Zidan
The thermal decompositions of nine mixed ligand complexes of Mn(II) containing picrate and mono- or bidentate nitrogen ligands were studied by thermogravimetry. The kinetics of decomposition were examined by using the Coats-Redfern and Horowitz-Metzger equations; the decomposition was in all cases of the first order. The activation energies and other kinetic parameters were computed. The decomposition mechanisms exhibited a similar character for all the studied compounds. It was observed from the TG curves that the complexes decomposed to give six-coordinate intermediates, formed from substitution of the picrate into the inner coordination sphere. These intermediates decomposed to Mn(II) picrate and finally to Mn2O3.
1,2,3-Benzotriazole /1,2,3-BT/ has been used for the radiochemical separation of Mn/II/ employing solvent extraction technique. Based on various parameters such as pH effect, time of equilibration and effect of various solvents, etc. the ideal conditions for the extraction of Mn/II/ was evaluated. The stoichiometry of the metal to reagent was determined by the substoichiometric extraction and slope-ratio method and found to be 12. The effect of anions on the extraction value of Mn/II/ revealed that a large number of anions do not interfere. Separation factors for various elements were also studied and the extraction found to be selective.
The TG and DTA of a new series of Mn(II) and Cu(II) complexes with a number of newly prepared bisazo-dianil ligands were studied
in the temperature range (20-700C). The TG and DTG curves display to main steps, the first one within the temperature range
(25-330C) correspond to the elimination of water or and ethanol from the complexes. The second step within the range (350-625C)
is due to the decomposition of the complexes yielding the metal oxides as the final product. The rate constants of the dehydration
and decomposition reactions were determined, from which some kinetic parameters were evaluated. The DTA curves show that the
dehydration of the metal complexes is an endothermic reaction. In all cases the anhydrous metal complexes undergo exothermic
decomposition reactions to give the metal oxide. The thermodynamic parameters (ΔE, ΔH, ΔS, ΔG) for the occurring processes
are calculated. The electrical conductivities of the solid complexes were measured and the activation energy of the complex
and its free ligand are also calculated.
Authors:Wiesława Ferenc, Beata Bocian, and J. Sarzyński
Four new complexes of 2,3,4-trimethoxybenzoic acid
anion with manganese(II), cobalt(II), nickel(II) and copper(II) cations were
synthesized, analysed and characterized by standard chemical and physical
methods. 2,3,4-Trimethoxybenzoates of Mn(II), Co(II), Ni(II) and Cu(II) are
polycrystalline compounds with colours typical for M(II) ions. The carboxylate
group in the anhydrous complexes of Mn(II), Co(II) and Ni(II) is monodentate
and in that of Cu(II) monohydrate is bidentate bridging one. The anhydrous
complexes of Mn(II), Co(II) and Ni(II) heated in air to 1273 K are stable
up to 505–517 K. Next in the range of 505–1205 K they decompose
to the following oxides: Mn3O4,
CoO, NiO. The complex of Cu(II) is stable up to 390 K, and next in the range
of 390–443 K it loses one molecule of water. The final product of its
decomposition is CuO. The solubility in water at 293 K is of the order of
10–3 mol dm–3
for the Mn(II) complex and 10–4 mol dm–3
for Co(II), Ni(II) and Cu(II) complexes. The magnetic moment values of Mn2+,
Co2+, Ni2+ and Cu2+
ions in 2,3,4-trimethoxybenzoates experimentally determined in the range of
77–300 K change from 5.64–6.57 μB (for Mn2+),
4.73–5.17 μB (for Co2+), 3.26–3.35 μB
(for Ni2+) and 0.27–1.42 μB (for Cu2+).
2,3,4-Trimethoxybenzoates of Mn(II), Co(II) and Ni(II) follow the Curie–Weiss
law, whereas that of Cu(II) forms a dimer.
The extraction behavior of Mn(II), Co(II), Cr(III) and Fe(III) has been studied in high molecular weight amines from succinic acid medium. The effect of different variables, like, type of amine, effect of pretreatment of amine with various acids, type of diluent and concentration of metal, succinate, hydrogen ions and amine, has been investigated. Extraction of Cr(III) and Fe(III) species is proposed and some binary separations achieved.