VOLUME 21, NO1, MAR 1999

N-vinylcarbazole-divinylbenzene copolymer. The effect of different diluents on the formation of porous structure in suspension polymerization

N-Vinylcarbazole(NVC)-divinylbenzene(DVB) copolymer beads of porous structure were prepared by suspension polymerization in different solvating, non-solvating and mixture of diluents. These diluents having different affinities for the copolymers, produced changes in their morphology particularly with respect to porosity, pore size distribution and specific surface area and subsequently density and mechanical strength It was observed that the use of relatively less solvating diluent results in more porous, large pore size distribution and large surface area and subsequently small density and poor mechanical strength copolymer beads and vice versa under the given experimental conditions. The use of a mixture of an appropriate solvating and non-solvating diluents could result in copolymer beads of desired characteristics.The cation-exchange resins prepared by the sulfonation of the respective copolymer beads were checked for their Na+ ions capacity. The capacity varies from 3.45 to 4.10 meq/g. That means it does not change markedly with the change in diluent or mixture of diluents under the given experimental conditions.read more

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EJAZ UR REHMAN ,RIFFAT NAHEED ,MUHAMMAD ABDUL HAMID ,MUHAMMAD FUZAIL ,

Conductance study of the thermodynamics of some transition and heavy metal complexes with aza-18-crown-6 in dimethylformamide solution

 A conductance study of the interaction between TI+, Ag+, Co2+, Ni2+, Cu2+, Zn2+, Cd2+, and Pb2+ ions and aza-18-crown-6 in dimethylformamide solution has been carried out at various temperatures The formation constants of the resulting 1:1 complexes were determined from the molar conductance-mole ratio data and found to vary in the order TI+ > Ag+ > Pb2+ > Cd2+ > Cu2+ > Ni2+ Co2+ > Zn2+. The enthalpy and entropy of complexation reactions were determined from the temperature dependence of the formation constants. In the ease of all M2+-A18C6 systems studied, the resulting complexes are both enthalpy and entropy stabilized While, in the ease of Ag+ and TIC ions, the resulting complexes with A18C6 are enthalpy stablizied but entropy destabilized.read more

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MOJTABA SHAMSPUR ,HAMID REZA POURETEDAL ,

Dehydroacetic acid oxime as a new ligand for spectrophotometric determination of copper

Dehydroacetic acid oxime (DAO) has been used as a ligand for spectrophotometric determination of copper. The reaction takes place in slightly acidic medium and the Cu-DAO complex absorbs radiation in the visible region at 460 nm The absorption is free from any spectral interference as far as the reagent itself is concerned.read more

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M AMINUDDIN ,JAVED IQBAL ,J I GILL ,

The extraction and recovery of copper (II) with tertiary amines

The work describes a comparative study with various high molecular weight tertiary amines to develop a hydrometallurgical method for the extraction and recovery of copper (II) from different aqueous acidic media. Limits such as, the effect of acid, extractant, and stripping agents concentration, time of contact, and diverse ions were optimized. Maximum percentage extraction and recovery of copper (II) ions were achieved with 5% solution of trioctylamine in benzene.read more

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MIHAMMAD ALI QAISAR ,TAJ ALI KHAN ,KAMIN KHAN ,

Flow injection spectrophotometric determination of choline using immobilized enzymes

A flaw injection spectrophotometric method is described for the determination of choline based on the production of hydrogen peroxide from choline using immobilized choline oxidase mini-column. The product is mixed downstream to oxidize iodide into tiiodide at an elevated pH in the presence of molybdenum (VI), and the absorbance of the triiodide was monitored at 352 nm The detection limit is lower than 0.01 mmol/L with relative standard deviation of 1.5% over the range 0.1-1.0 mmol/L. The sample throughput was 40/h.read more

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M YAQOOB ,A NABI ,M MASOOM YANSINZAI ,S H SHAH ,

Analysis of impurities in silver matrix by atomic absorption spectrophotometry

 A procedure for the analysis of aluminium, chromium, copper, lead mercury, nickel and zinc mainly using flame less atomic absorption spectrophotometry has been described. The results depict that the presence of silver does not introduce any significant interference, when standards are prepared in matching silver matrix solutions The calibration curves obey the straight-line equations passing through the origin. Thus the separation of silver matrix from the analyte solutions is not necessary. The method has been successfully applied for the analysis of silver foils, wires, battery grade silver oxides and silver nitrate samples containing analyte elements in the concentration range 2 to 40 ppm.read more

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DIN MOHAMMAD ,RIZWAN HUSSAIN ,MOHAMMAD ISHAQUE ,

Pollution studies of Kabul River and its tributaries for the assessment of organic strength and Fecal coliform

Thirty eight samples of water from Kabul River and its tributaries starting from Warsak Reservoir to the confluence point of Kabul and Indus Rivers covering a stretch of about 90 km and the waste water being discharged by different drains into the river were collected systematically and analysed for total organic strength as Chemical Oxygen Demand (COD) and degradable organics as Biological Oxygen Demand (BOD) using standard methods. River water samples from different locations were also analysed bacteriologically for Fecal coliforms. All the waste water samples and river water at a few locations were found to be high in COD, BOD and Fecal coliform rendering it unfit for irrigation and human consumption The results also suggest that the effluents from Khazana Sugar Mills, Colony Sarhad Textile Mills, Amarjee Paper and Paper Board Mills and from different tanneries are the main sources of organic pollution in the Kabul River. Reduction in fish crop in Kabul River could be referred to the increased organic pollution.read more

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A R KHAN ,KAMIN KHAN ,SURRAYA WADUD ,M AKIF ,

Study of pollution in Rawal Lake

 It was intended to establish effect of pollution on quality of water of Rawal Lake, Islamabad. Six stations were located for collection of water. The data collected and analyzed so far indicated increasing pollution in the lake. Increase in growth of hydrophytes is quite evident, leading towards process of eutrophication of the lake.read more

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MUHAMMAD NSIAR ,M YOUNAS KALEEM ,MUSHTAQ AHMAD ,M ISHAQ ALI KHAN ,

Comparative studies of electron impact and thermolytic fragmentation of 3-phenyl-4-(anilinomethylene)-5-isoxazolone

It has been observed that correlation exist between the electron impact-induced fragmentation of a molecule and its thermolysis products.read more

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AMJAD HUSSIAN ,

Electron ionization mass spectrometric studies of 1,2-dihydro-2-[2-(1 ',3 '-benzo-thiazolyl)]-3H-indazol-3-one and 1,2-dihydro-2-(3 ',4 '-dimethylphenyl)-6,7-dimethoxy-3H-indazol-3-one

Electron ionization mass spectra of 1,2-dihydro-2-[2-(1',3'-benzothiazo-lyl)]-3H-indazol-3-one (2a) and 1,2-dihydro-2(3',4'-dimethylphenyl)-6,7-dimethoxy-3H-indazol-3-one (2b) and their related compounds (1a-b) are described with the help of LREIMS. The molecular formulae are further confirmed by high resolution peak matching of molecular ion peaks exhibited by EIMS.read more

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I REHMAN ,ABDUL R RAZA ,NASIM H RAMA ,