VOLUME 15, NO2, JUN 1993

THERMODYNAMICS OF ADSORPTION OF DYES ON ACTIVATED SILICA-GEL

A quantitative treatment pertaining to the study of thermodynamics Of adsorption of sulphorhodamine-B, acid red-4 and acid green-25 on activated silica gel through the evaluation of the Gibbs free energy, DELTAG, as a function Of temperature is presented. The DELTAG values are computed by employing the Gibbs adsorption equation by making use of the areas under the m-1nCs curves. The enthalpy, DELTAH, and the entropy, DELTAS, has also been calculated. The results are discussed in terms of the nature of the adsorbates.read more

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MAQSOOD HUSSAIN ,MUHAMMAD JAVED IQBAL ,

ADDITION OF 2-PERCENT ETHENE, PROPENE AND ACETYLENE IN THE CO-HYDROGENATION EXPERIMENT FOR THE DETERMINATION OF CHAIN GROWTH INTERMEDIATE IN THE FISHER TROPSCH SYNTHESIS ON RU ALUMINA-SUPPORTED CATALYST

The alumina supported ruthenium catalyst was prepared by co-impregnation method and characterised using B.E.T. surface, area measurement and Atomic Absorption Spectroscopy. The prepared catalyst was subjected to Fischer Tropsch Synthesis with simultaneous addition of 2% ethene, propene and acetylene in the feed stream to investigate the possible intermediate in the CO/H-2 reaction. From the experimental data it could be concluded that the formation of > CH2 group on the surface of the catalyst is the possible intermediate which initiate the chain propagation for the formation of higher hydrocarbons in the Fischer Tropsch Reaction.read more

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TAJAMUL HUSSAIN ,

CHARACTERIZATION OF METAL-DOPED CARBONS BY MERCURY POROSIMETRY

Surface areas and pore structure studies were carried out for metal doped carbons (Ni, Cu, Cd and Zn) containing different fraction of metals. It is observed that mercury intrusion and extrusion curves are irreversible giving the evidence of ''ink bottle'' pores in the carbon samples. Results indicate that the surface areas obtained by mercury porosimetry are very small comparative to the surface areas determined by nitrogen adsorption. Low values of surface areas by mercury porosimetry indicate the presence of a microporous system which is only accessible to nitrogen molecules but not to mercury.read more

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M SALEEM ,F MAHMOOD ,M AFZAL ,

PREPARATION AND DISTRIBUTION MEASUREMENTS FOR POLYETHYLENE SINGLE-CRYSTALS FOR VARIOUS TYPE OF SIZES

The size and size distribution measurements were carried out for single crystals of poly ethylene by an optical microscope. The single crystals were obtained from the dilute solutions (0.1 %) of polyethylene in p-xylene in the temperature range 74-94-degrees-C. It was observed that the mean size of the crystals increase from 15.11 to 32.98 mum at magnification 320 (47.22 mmu- 103.66 mmu) with increase in crystallization temperature, which may be attributed to the uncoiling of the folds with the rise in temperature.read more

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KHALID MAHMOOD ,NOOR AHMAD ,

TEMPERATURE-PROGRAMMED DESORPTION (TPD) AND TEMPERATURE-PROGRAMMED REDUCTION (TPR) STUDIES OF ALUMINA-SUPPORTED PLOYCRYSTALLINE RU/MN BIMETALLIC SYSTEM

TPR and TPD studies were carried out on alumina supported Ru:Mn system. From the experimental data it could be conluded that the addition of the Mn produces new sites which are responsible for the production of high molecular weight hydrocarbons. The data has been discussed in terms of the modification of surface electronically and geometrically by the addition Mn to the Ru/Al2O3 system.read more

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S TAJAMUL HUSSAIN ,

POTENTIAL-ENERGY SURFACES CALCULATIONS FOR ION-PAIRS .1. A COMPARISON OF PEACOCK AND SIMONETTA METHOD

In order to study the efficacy of Peacock method, potential energy surfaces calculations were carried out on Naphthalene (molecule, anionradical and dianion) and p-dicyanobenzene a (anion radical) Peacock method. The results obtained were compared with those from Simonetta method. It was found that as regards the structure of ionpairs, both methods give the same results for conjugated hydrocarbons. Some molecular plane potential surface calculations were carried out for tetraphenylethylene (Neutral, anion radical and dianion).read more

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RUMANA QURESHI ,

SPECTROSCOPIC STUDIES OF SOME URANYL COMPLEXES OF TETRADENTATE SCHIFF-BASES

The dioxouranium complex of eight tetradentate ligands bis(isopropanoylacetone) dl-stilbenediimine(dl-H2PA2S), bis(isopropanoylacetone)meso-stilbenediimine(meso-H2PA2S), bis(acetylacetone) dl-H2HAP2S), bis(o-hydroxyacetophenone phenylethylenediiminedl-stilbenediimine (dl-H2AA2S), bis(o-hydroxyacetophenone) meso-stilbenediimine(meso-H2HAP2S), bis-(o-hydroxyacetophenone)dl-stilbeneiimine (dl-H2HAP2Pen), bis (salicylaldehyde) tetramethylethylenediimine (H2SA2Ten) and bis(salicylal dehyde) phenylpropylenediimine (H2SA2PP) have been prepared. The uranyl complexes of H2SA2Ten and H2SA2PP are precipitated as neutral complexes, but remaining are obtained as dinitro derivatives. The complexes are characterised by IR, H-1-NMR and spectrophotometric techniques.read more

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Z P MEMON ,A K TALPUR ,G Q KHASKHELY ,R B BOZDAR ,M Y KHUHAWAR ,

CONDUCTOMETRIC STUDY OF CHLOROACETIC ACID IN BINARY MIXTURE OF WATER WITH N,N-DIMETHYLFORMAMIDE, ACETONE AND ACETONITRILE AT 298.15-K

Molar conductances of dilute solutions of chloroacetic acid in binary mixtures of N,N-dimethylforamide, acetone and acetonitrile with water have been measured at 298.15 K. The data were fitted to the Lee - Wheaton conductance equation for the derivation of thermodynamic dissociation constants and limiting molar conductances. The results are discussed in terms Of solvent effect on the ionization of acid as the composition of solvent mixture is varied.read more

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M SADIQ KHAN NIAZI ,

PYROLYSIS OF 3-PHENYL-4-(2-METHOXYPHENYLMETHYLENE)-5-ISOXAZOLONE TO GIVE O-METHOXYPHENYLACETYLENE, BENZOFURAN AND PHENYLCYANIDE

Pyrolysis of 3-phenyl-4-(2-methoxyphenylmethylene)-5-isoxazolone produces o-methoxy -phenylacetylene, benzofuran and phenylcyanide.read more

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J PARRICK ,AMJAD HUSSAIN ,

EFFECT OF METAL-IONS ON THE FORMATION AND DESTRUCTION OF HYDROGEN-PEROXIDE IN MEDIA USED FOR MAMMALIAN ADIPOCYTES INCUBATION

The activity of transition metals under incubation conditions is of particular interest because these metal ions induced an insulin-like effect in fat cells which is reminiscent of that of hydrogen peroxide. It is possible that in one of its bound states nickel may stimulate hydrogen or lipid peroxide accumulation which in turn can account for this effect on adipocytes during in vitro incubation. In this study using a simple model system the role of metal ions on the formation and destruction of hydrogen peroxide is illustrated in medium used for mammalian adipocytes in-cubation. It is interesting to note that the only metal which generated hydrogen peroxide in the medium was copper when its concentration was 10 muM. The metals associated with destruction of hydrogen peroxide were cobalt, copper and manganese. Iron and nickel played no role at all.read more

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JAMES ISLWYN DAVIES ,RIAZ AHMAD RIAZ ,