VOLUME 17, NO2, JUN 1995

EFFECT OF NEUTRON AND GAMMA-RADIATIONS ON ZEOLITE AND ZEOTYPE MATERIALS

The influence of gamma- and (n, gamma-radiation on the cation exchange and the structure of zeolite and zeotype materials has been studied. Samples were subjected to different doses of gamma-irradiation varying between 0.5 and 10 MGy and Neutron irradiation flux varied from 1.14 x 10(17) to 3.88 x 10(17) n cm(.2). Structural effects consequent to gamma-irradiation were examined by X-ray diffraction, electron scanning micrograph and FTIR measurements. Neutron and gamma-irradiation did not lead any appreciable change in the structure, however, the displacement cations to ''locked-in sites results partial reduced barium and caesium uptake. The decrease of the intensities of the absorption bands of the hydroxy-groups reveals that gamma-irradiation has a strong dehydrating influence. The effect of gamma-radiation on UO22+ and Am3+ uptake into NH4-L and NH4-SAPO-34 was also observed. K-d of the uranyl ions increased with increasing pH up to 6.3. At pH> 3.5. the uranyl ions were precipitated, and consequently the K-d values were containued to increase.read more

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SITI AMINI ,SHAHID KHAN DURRANI ,

THERMODYNAMIC DISSOCIATION STUDIES OF DL-CYSTEINE AT DIFFERENT TEMPERATURES AND IN WATER-ORGANIC SOLVENT SYSTEMS

Thermodynamic dissociation constants of a d1-Cysteine were determined at varying temperatures ranging from 25 degrees C to 50 degrees C at 5 degrees C interval and in 10, 20, 30 and 40 percent v/v dioxane/water, methanol/water and ethanol/water systems. The influence of the composition of the medium on the dissociation equilibria of d1-cysteine was also investigated. A computer program was written in GW-BASIC which is a modified version of earlier written program in FORTRAN IV, developed to be used with IBM PC XT/AT or compatible computers.read more

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K M BHATTI ,A T MUFTI ,SAEED UDDIN ,A W K KHANZADA ,

KINETICS OF STRONTIUM IONS ADSORPTION ON ACTIVATED-CHARCOAL FROM AQUEOUS-SOLUTIONS

Batch kinetics of strontium ions adsorption on the activated charcoal from aqueous solutions was studied within me temperature rang 283-313K. It is observed that the hydrolyzed strontium diffuses into the micropores of the activated charcoal and the film diffusion, with an activation energy 6.80 kJ/mol, is the rate determining step.read more

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RIAZ QADEER ,IMTIAZ HANIF ,JAVED HANIF ,

KINETICS OF THE REDUCTIONS OF OXYHALOGENS WITH DIMERIC TUNGSTEN(V) IN AQUEOUS ACIDIC MEDIUM

The dinuclear tungsten(V)-W2O42+ (aq) dimer (structure 1) is readily oxidized to W (VI) by a number of oxyhalogen species in aqueous acidic media. Oxidizing agents, BrO3., HBrO2, HOCl2 and HOCl with excess reductant yield the corresponding halide ions, and reduction of ClO3. yield Cl-., even when the oxidant is in large excess. The reaction of IO3. is complicated by relatively rapid reaction between I-. and IO3. at low pH, which undergoes further slow reduction yielding I-2. Reduction of ClO3. and BrO3. are independent of hydrogen ion concentration in the range 0.1 - 1.0 M[H+], but reduction of the acids HBrO2, HClO2 and H5IO6 are found to be inverse-first order in [H+]. Hypochlorous acid appears to react via a [(W-V)(2)-ClOH] adduct, which undergoes deprotonation (PK=1.5), prior to electron transfer.read more

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K MAHMOOD ,ABBAS H KHAN ,M AKRAM ,Z MAHMOOD ,

KINETICS AND THERMODYNAMICS OF SOME METAL-IONS ADSORPTION ON ACTIVATED-CHARCOAL FROM AQUEOUS-SOLUTIONS

The kinetics and thermodynamics of metal ions (Sr2+, Sm3+, Gd3+, Th4+ and UO22+ adsorption from aqueous solutions on activated charcoal have been investigated. The adsorption process of metal ions proceeds via two stages, the first stage is rather fast followed by a much slower om Bangham equation was applied to study the kinetics of metal ions adsorption. It is observed that the diffusion of metal ions into the micropores of the activated charcoal controls the kinetics of the adsorption process. various thermodynamic quantities, Delta H, Delta S, Delta G, were computed from equilibrium constant, k(c) values. The results show that the adsorption of the metal ions on activated charcoal is an endothermic process.read more

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M SALEEM ,JAVED HANIF ,RIAZ QADEER ,M AFZAL ,

DETERMINATION OF SELECTED CATIONS, UTILIZING FLUORESCENCE ENHANCEMENT PHENOMENON OF N-METHYL ANTHRANILIC ACID (NMAA)

The effected of cations like Na+, K+, Cd2+, Cu-2+. Ag+, Zn2+, Co2+, Ni2+, Pb2+, Fe3+, Al3+ and Cr3+ on the fluorescence intensity of NMAA was studied. All the cations investigated with the exception of Na+ and K+ caused an enhancement in the fluorescence intensity of NMAA. Based on the florescence enhancement effect, these cations were divided into three groups. The fluorescence enhancement phenomenon was utilized for spectrofluorimetric determination of these cations in aqueous samples. Limit detection for each cation was also investigated and reported in this paper.read more

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M ARFAN ,HAIDER SHAH JADOON ,M RASUL JAN ,

PREPARATION AND SPECTROSCOPIC STUDIES OF COPPER(II), NICKEL(II), PALLADIUM(II) AND OXOVANADIUM(IV) CHELATES OF FLUORINATED SCHIFF-BASES

The copper(II), nickel(II) palladium(II) and oxovanadium(IV) chelates of two tetra-denate Schiff bases, N,N'-ethylene bis(1,1,1-trifluoro-6-methyl-2-oxoheptan-4-imine) (H2TF-IVA(2)en) and 1,2-propylenebis(1,1,1-trifluoro-6-methyl-2-oxoheptan-4-imine) (H(2)TFIVA(2)pn) have been prepared. The reagents and their metal chelates have been characterized using infrared, mass, H-1-NMR and UV/Vis spectrophotometry. The structures have been assigned to ligand and their metal chelates.read more

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M Y KHUHAWAR ,ALTAF I SOOMRO ,

SPECTRAL INVESTIGATIONS ON BIS MONOTHIOACETYLACETONATE COMPLEXES OF NI(II), PD(II), CN(II) AND ZN(II)

Several complexes of some monothioacetylacetonate (TAA) of four-coordinate nickel, copper, zinc and palladium have been prepared in order to examine their low-frequency FT-IR spectra. On tbe basis of their IR data relationship between structural changes caused by metal substitution in these complexes is suggested.read more

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J SCIESINSKI ,L M PRONIEWICZ ,D T HAWORTH ,M DAS ,

HIGH-PERFORMANCE LIQUID-CHROMATOGRAPHIC DETERMINATION OF NICKEL IN A NICKEL-ALUMINUM ALLOY USING SPECTROFLUOROMETRIC DETECTION

Copper(II), nickel(II), palladium(II) and oxovanadium(IV) chelates of bis(salicylaldehyde) tetramethylethylenediimine (H(2)SA(2)Ten) were separated on normal phase high performance liquid chromatographic (HPLC) column, Si 100, 5 mu. The chelates were eluted with a ternary mixtures of 1,2-dichloroethane: chloroform: acetonitrile (70:28:2, v/v/v). The detection was achieved using a spectrofluorimetric detector. The linear calibration range for each of the complex at optimized spectrofluorimetric detection were determined. A solvent extraction procedure in chloroform was examined for the determination of nickel and method was applied for the estimation of nickel in a nickel aluminum alloy.read more

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F C NACHNANI ,G Q KHASKHELY ,M Y KHUHAWAR ,S N LANJWANI ,

A VOLUMETRIC METHOD FOR THE DETERMINATION OF SULFUR FROM ORGANIC-COMPOUNDS

A volumetric procedure has been described for the determination of sulphur from organic compounds. N-bromosuccinimide displaces iodine from potassium iodide which in turn reads with sulphide and oxidizes it to sulphur. N-bromosuccinimide an he used as a primary standard and kept for several days if refrigerated and protected from light. The method is rapid, convenient and accurate.read more

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M SARWAR ,MS. RUKHSANA ,FARHAT JAMSHAID ,