Halis Ölmez

Thermal Studies on Solid Complexes of Saccharin with Divalent Transition Metal Ions

The thermal decompositions of Mn(II), Fe(II), Co(II), Ni(II), Cu(II) and Zn(II) complexes of saccharin were studied in static air atmosphere. All of the complexes contain four molecules of coordination water and two molecules of crystallization water. The water molecules were removed in a single stage, except from the Zn(II) complex, which exhibited two endothermic effects. The dehydration process was usually accompanied by a sharp colour change. The anhydrous complexes exhibited a phase transition and the decomposition or combustion of saccharin occurred in the second and subsequent stages. The final decomposition products were identified by XRPD as the respective metal oxides. The kinetic parameters, such as the order of reaction and energy of activation for the dehydration stage, were evaluated and the thermal stabilities of the complexes are discussed.

THE EFFECTS OF PHOSPHOGYPSUM ON THE SETTING AND MECHANICAL PROPERTIES OF PORTLAND CEMENT AND TRASS CEMENT

Abstract Phosphogypsum, the by-product of phosphoric acid industry, consists of CaSO 4 .2 H 2 O and contains some impurities such as P 2 O 5 , F and organic substances. These impurities seriously restrict the industrial use of phosphogypsum in cement industry as a retarder. In this study, the effects of phosphogypsum and purified phosphogypsum on the hydration of Portland cement and trass cement were investigated by measuring setting time, strengths of pastes, and chemical analysis as well as the electron microscopic (SEM) observation of the hydration products. It was concluded that untreated phosphogypsum can be used as a retarder directly in trass cement, whereas Portland cement requires purified phosphogypsum.

The influence of ethanolamines on the hydration and mechanical properties of portland cement

Abstract The effect of ethanolamines—monoethanolamine (MEA), diethanolamine (DEA), triethanolamine (TEA)—on the hydration, mechanical and surface properties of the white Portland cement pastes (white PC) has been investigated. The cement pastes with and without admixtures were cured at various hydration times ranging from 1 day to 90 days. Hydration development of cement pastes were followed by setting times, flexural and compressive strengths, specific surface area measurements and thermal analysis techniques. The measurements showed that all these admixtures retard the hydration of white Portland cement in order TEA>DEA>MEA.

Spectrothermal studies on Co(II), Ni(II), Cu(II) and Zn(II) salicylato (1,10-phenanthroline) complexes

The cobalt, nickel, copper and zinc atoms in bis(1,10-phenanthroline)bis(salicylato-O)metal(II) monomeric octahedral complexes [M(Hsal)2(phen)2]·nH2O, (M: Co(II), n=1; Cu(II), n=1.5 and Ni(II), Zn(II), n=2) are coordinated by the salicylato monoanion (Hsal) through the carboxyl oxygen in a monodentate fashion and by the 1,10-phenanthroline (phen) molecule through the two amine nitrogen atoms in a bidentate chelating manner. On the basis of the DTGmax, the thermal stability of the hydrated complexes follows order: Ni(II) (149°C)>Co(II) (134°C)>Zn(II) (132°C)>Cu(II) (68°C) in static air atmosphere. In the second stage, the pyrolysis of the anhydrous complexes takes place. The third stage of decomposition is associated with a strong exothermic oxidation process (DTA curves: 410, 453, 500 and 450°C for the Co(II), Ni(II), Cu(II) and Zn(II) complexes, respectively). The final decomposition products, namely CoO, NiO, CuO and ZnO, were identified by IR spectroscopy.

Synthesis, spectroscopy, thermal behaviour and molecular structure of orotatotriethanolaminecopper(II) monohydrate

Abstract The orotatotriethanolaminecopper(II) monohydrate, [Cu(C5H2N2O4)(C6H15NO3)] · H2O, has been synthesized and characterized with physico-chemical methods (IR and UV-Vis spectroscopy, magnetic susceptibility, conductivity and thermoanalytical measurements) and X-ray diffraction. The structure derived from physico-chemical methods is consistent with that of the X-ray diffraction. The compound crystallizes in the monoclinic system, space group P21/n, with a = 8.6282(12), b = 16.9919(18), c = 10.6985(15) Å, β = 110.08(3)°, V = 1473.1(3) Å3, Z = 4. The copper atom is chelated by the deprotonated nitrogen pyrimidine atom and by the carboxylate oxygen atom of the orotate dianion ligand, and by the nitrogen and oxygen atoms of the triethanolamine ligand. The title compound has a distorted octahedral coordination geometry.

The mechanical properties of supersulphated cement containing phosphogypsum

Abstract The use of phosphogypsum in the making of supersulphated cement (SSC) and mechanical properties of the SSC pastes were investigated. Setting times of SSC pastes were shortened with increasing phosphoanhydrite and Portland cement clinker content. The SSC pastes prepared using tap water were cured in both tap water and seawater for up to 90 days. The SSC pastes containing 85% slag, 10% phosphoanhydrite and 5% clinker were found to produce the highest strength values at 90 days. The SSC pastes cured in synthetic seawater generally showed much lower strength development. Volume changes of SSC pastes hydrated in both tap water and seawater differ significantly from each other.

Infrared study on the refinement of phosphogypsum for cements

Abstract Phosphogypsum, the by-product of phosphoric acid manufacture, is considered as a gypsum for the control of the setting time of Portland cement and trass cement. However, it is well known that impurities, usually included in phosphogypsum, injuriously affect the hydration of cement. The object of this paper is to clarify the characters of impurities in phosphogypsum produced in Turkey and to obtain refined phosphogypsum using various methods following IR technique.

Spectroscopic and Thermal Studies of bis(N,N′‐Dimethylethylenediamine) and bis(N,N‐Dimethylethylenediamine)saccharinato Complexes of Co(II), Ni(II), and Cu(II)

The mixed‐ligand saccharin (Hsac) complexes of Co(II), Ni(II) and Cu(II) with N,N′‐dimethylethylenediamine (dmen), and N,N‐dimethylethylenediamine (ndmen) (Figure 1) were synthesized and characterized by elemental analysis, magnetic susceptibility, spectral (UV‐Vis and FT‐IR) methods, and simultaneous TG, DTG and DTA techniques. The complexes have pseudooctahedral geometries with two dimethylethylenediamine molecules coordinated to the metal ions as chelating ligands through their two nitrogen atoms and two monodentate saccharinato ligands in the trans positions for the complexes of the type [M(sac–O)2(dmen)2] (M = Co(II), Ni(II)), and [M(sac–N)2(ndmen)2] (M = Co(II), Ni(II), Cu(II)) and two aqua ligands in the trans positions in [Cu(H2O)2(dmen)2](sac)2. (sac–O; sac‐N = the saccharinato ligand may be coordinated to the metal ions through their carbonyl oxygen or their nitrogen atom, respectively). The decomposition mechanism and thermal stability of the solid complexes are interpreted in terms of their structures. The thermal stability order of the investigated complexes is Cu(II) > Co(II) > Ni(II) while the bis(N,N′,‐dimethylethylenediamine) complexes are thermally less stable than those of bis(N,N‐dimethylethylenediamine). The final decomposition products—the respective metal oxides—were identified by FT‐IR spectroscopy.

Distribution of uranium in the production of triple superphosphate (TSP) fertilizer and phosphoric acid

In this study the distribution of uranium, which is one of the radioactive elements present in phosphate fertilizers was investigated in different steps of the triple superphosphate (TSP) production process. The uranium in phosphate rock, phosphoric acid, phosphogypsum and TSP was extracted into the organic phase by using the TOPO extraction method. The uranium contents of these materials were determined by measuring the absorbance of the formed (pH 7.6) uranyl bromo-PADAP [uranyl(2-(5-bromo-2-pyridylazo)-5-diethylaminophenol)] complex solutions at 574 nm against blank. It was found that 50% of the uranium is dissolved in the acid during the production of phosphoric acid while the remainder is precipitated with phosphogypsum residue. The observations showed that in the second step, the sum of uranium in phosphate rock and phosphoric acid completely passed into TSP in the TSP manufacturing process.

Thermal decompositions of some divalent transition metal complexes of triethanolamine

The thermal behaviours of the Ti(II), Mn(II), Fe(II), Ni(II), Cu(II) and Zn(II) complexes of triethanolamine were studied by means of thermogravimetry, differential thermogravimetry, differential thermal analysis infrared spectrophotometry and elemental analysis. The sequence of thermal stability of the metal complexes, determined by using the initial decomposition temperature, was found to be Ti(II)≅Mn(II)>Fe(II)>Ni(II)>Zn(II)>Cu(II). Some of the kinetic parameters, such as the activation energy and order of reaction for the initial decomposition reaction, were calculated and the relationship between the thermal stability and the chemical structure of the complexes is discussed.ZusammenfassungMittels TG, DTG, IR-Spektrofotometrie und Elementaranalyse wurde das thermische Verhalten der Ti(II)-, Mn(II)-, Fe(II)-, Ni(II)-, Cu(II)-, und Zn(II)- Komplexe von Triethanolamin untersucht. Die anhand der Temperatur für die einsetzende Zersetzung ermittelte Reinhenfolge für die thermische Stabilität der Metallkomplexe lautet: Ti(II)≅Mn(II)>Fe(II)>Ni(II)>Zn(II)>Cu(II). Einige der kinetischen Parameter, wie Aktivierungsenergie und Reaktionsordnung für die einsetzende Zersetzungsreaktion wurden berechnet und die Beziehung zwischen Stabilität und chemischer Struktur der Komplexe besprochen.