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  • Author or Editor: B. Rao x
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Abstract  

Co(II), Ni(II), Cu(II) and Cd(II) chelates with 1-aminoethylidenediphosphonic acid (AEDP, H4L1), α-amino benzylidene diphosphonic acid (ABDP, H4L2), 1-amino-2-carboxyethane-1,1-diphosphonic acid (ACEDP, H5L3), 1,3-diaminopropane-1,1,3,3-tetraphosphonicacid (DAPTP, H8L4), ethylenediamine-N,N′-bis(dimethylmethylene phosphonic)acid (EDBDMPO, H4L5), O-phenylenediamine-N,N′-bis(dimethyl methylene phosphonic)acid (PDBDMPO, H4L6), diethylene triamine-N,N,N′,N′,NN″-penta(methylene phosphonic)acid (DETAPMPO, H10L7) and diethylene triamine-N,N″-bis(dimethyl methylene phosphonic)acid (DETBDMPO, H4L8) have been synthesised and were characterised by elemental and thermal analyses as well as by IR, UV–VIS, EPR and magnetic measurements. The first stage in the thermal decomposition process of these complexes shows the presence of water of hydration, the second denotes the removal of the coordinated water molecules. After the loss of water molecules, the organic part starts decomposing. The final decomposition product has been found to be the respective MO·P2O5. The data of the investigated complexes suggest octahedral geometry with respect to Co(II) and Ni(II) and tetragonally distorted octahedral geometry with respect to Cu(II). Antiferromagnetism has been inferred from magnetic moment data. Infrared spectral studies have been carried out to determine coordination sites.

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Abstract  

The present work deals with the determination of Cr/III/ by means of the substoichiometric isotope dilution method, using PAN, 1-/2-pyridylazo/-2-naphthol as a complexing agent. Chromium forms a 12 complex with PAN. Heating to 90°C for 3 min was necessary for complete complexation. The complex was extracted into chloroform at pH 3.5 /acetate buffer/. Tens of micrograms of chromium could be determined. Effect of diverse metal ions was also studied.

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Abstract  

The specific surface area of mercuric oxide has been measured by heterogeneous isotope exchange, gas adsorption, air-permeability and microscopic methods. Values obtained by the four methods were compared and explanations given for the observed differences.

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Abstract  

Catalysis of mixed oxide LaMnO3 was studied for the decomposition of hydrogen peroxide (H2O2). The catalyst was -irradiated in open petri dishes, vacuum, dry oxygen and moist oxygen. LaMnO3 irradiated in moist oxygen showed highest catalytic activity. X-ray photoelectron spectroscopic (XPS) studies were carried out to investigate the surface modifications occurred during -irradiaiton of LaMnO3. No significant change in the surface was noticed in LaMnO3 irradiated in vacuum and dry oxygen. However, LaMnO3 irradiated in moist oxygen and in open petri dishes showed the reduction of transition metal (MN3+ to Mn2+) which in turn leads to the formation of chemisorbed superoxide ions (O 2 ) and surface carbonate species (CO 3 2– ). The latter processes decreases the electrical conductivity by trapping the charge carriers. The hydrated electron generated by the radiolysis of moisture reduces the transition metal. A qualitative molecular orbital model has been proposed for the chemisorption of O 2 on the reduced transition metal centers (Mn2+).

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Abstract  

Electronspin resonance (ESR) studies of -irradiated LaNiO3 revealed the formation of chemisorbed superoxide ion (O 2 ) and F centers (electrons trapped in anion vacancies). X-ray photoelectron spectroscopy (XPS) showed that the -irradiation of LaNiO3 in the presence of moisture leads to the reduction of the transition metal (Ni3+ to Ni2+) which in turn facilitates the formation of O 2 and surface carbonate species (CO 3 2– ). A qualitative molecular orbital model has been proposed for the chemisorption of O 2 on the reduced transition metal centers (Ni2+). The hydrated electron generated by the radiolysis of moisture reduces the transition metal. Gamma-irradiated LaNiO3 shows enhanced catalytic activity for the decomposition of hydrogen peroxide (H2O2) and the increase in catalytic activity is attributed to the reduced metal content. The formation of chemisorbed oxygen decreases the electrical conductivity by trapping the charge carriers.

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Abstract  

Specific surface area of antimony oxide samples, one commercial and the other prepared from antimony trichloride have been measured by heterogeneous isotope exchange, gas adsorption, airpermeability and microscopic methods. Specific surface areas obtained by these four methods for the two samples were compared and the observed differences are explained.

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Abstract  

5–25 g of copper has been determined by exchange with zinc-65 labelled zinc sulphide. The effect of diverse ions on the determination has also been reported.

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Abstract  

Reactions of recoil38Cl atoms with CCl4 and C6H5Cl have been studied in presence of various high electron density scavengers. Relative reactivities of recoil38Cl towards the two components of these mixtures are determined using the model proposed by Urch.

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