VOLUME 27, NO5, OCT 2005

Thermal Analysis of Hydrated Cobalt (II) Exchanged X-type Zeolites

A series of five samples (6.80, 15.80, 20.10, 21.45, 22.00 Co2+ ions per unit cell) of Co2+ exchanged X-zeolites were prepared by cation exchanged method. The decrese in percentage exchange with increase in Co2+ ions in exchange solution suggest replacement of NaX ions from the supercages and also “volume effect” the zeolitic water contents and thermal stability of hydrated zeolite samples unexchanged and exchange were investigated by using thermo gravimetric analysis (TGA) and differential thermal analysis (DTA) techniques, under a constant flow of nitrogen as purge gas. The TGA study indicated total weight loss percentage of the zeolite samples from 18.87% to 26.70. the zeolite water contents and thermal stability increased with increase Co2+ ions in the zeolitic X. Two exothermic DTA curves at 585oC and 887oC for NaX and one up to about 830oC were recorded for Co X-zeolite samples, which indicated the collapse of crystalline aluminusilicate framework.read more

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K DAD ,R SHAHNAZ ,S AKBAR ,T H SHAH ,

Thermal Study of NaX Zeolite with Different Degrees of Cadmium Exchanged

Type X-zeolite in which 14.6, 31.00, 42.40, 57.80 and 59.00 Na+ ions have been exchanged with Cd2+ ions at 60oC. The decrease in % Cd2+ ion exchanged with increase in concentration of cadmium chloride solution is attributed to ‘salt imbibent’ and ‘concentration valency effect’. Thermogravimetric analysis (TGA) has been used to ascertain the zeolitic water content of all samples investigated. The thermal stability of NaX and CdX-zeolites samples were studied by using differential thermal analysis (DTA) curves as a function of calcinations temperature up to 1000oC and degree of Cd+ exchanged in type X-zeolite. The number of water molecules increases with increasing the Cd2+ ions per unit cell (p.u.c) in the zeolite. The DTA curves indicated that dehydrated NaX retained its crystal stability from 400 oC to 560oC and then re-crystallized to another form from 580 to 840 oC, while CdX-zeolite samples from 400 oC to 840 oC and then re-crystallized from 860 to 900 oC. The structures of NaX at above 880V and of CdX at above 960 oC collapse to an amorphous residue.read more

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T H SHAH ,K DAD ,S AKBAR ,R SHAHNAZ ,

Viscosity of some Aqueous Rare Earth Nitrate Solutions: Thermodynamics Aspect

Viscosities of aqueous solutions of La NO3)3, Ce(NO3)3, and Pr(NO3)3, in the concentration range of 0.2 to 1.0 M were measured in the temperature range of 293 to 333 K. Viscosity data obey the equation h = A exp (Eh/RT). Flow activation energies for all the three system were calculated. Various thermodynamics parameters i.e. DH, DS and DG for these systems were also evaluatedread more

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R QADEER ,N KHALID ,

Determination of Cu(II) with 1-Nitroso-2-naphhol in Micellar Medium by Derivative Spectrophotometry

A spectrometric and first derivative spectrometric determination of copper (II) is carried out with 1-nitroso-2-naphthol as complexing reagent in aqueous phase using non-ionic surfactant Tween 40. The copper is determined in the range 1.7-120 ng ml-1 with detection limit (2α) of 1.7ng/ml-1. The molar absorptivity and sandell’s sensitivity are 1.90 x (104 mol-1cm-1) and 7.9ng cm-2 at 483.5 nm. The optimum pH of the complex is 9. The critical micelle concentration (cmc) of Tween 40n is 5%. Absorption a studies in the first derivative mode is carries out to determine the absorption maximum of the complex for higher sensitivity and to overcome interference due to presence of certain metal ions. The present’s method is compared with that of AAS and no sufficant difference is noted between the two methods at 95% confidence level. The method has been applied for the determination of Cu(II) in industrial waste samples.  read more

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G A SHAR ,G A SOOMRO ,

8-Hydroxyquinoline as a Complexing Reagent for the Determination of Cd(II) in Micellar Medium

Spectrometric determination of cadmium(II) is carried out with 8-hydroxyquinoline as a complexing reagents in aqueous using cationic surfactant cetylpyrdinium chloride. Beer’s law is obeyed over the concentration range 0.5-8.0 mg m1-. The lmax molar absorption molar absorptivity and sandell’s sensitivity were 400 nm; emax = 0.75 x 104 mol-1dm3.cm-1 is 0.75 and (14.9) ng cm-2. Validation of this method has been made by comparing the results with those obtained by Atomic Absorption Spectroscopy (AAS) No significant difference was observed in the result obtained by the two methods at 95% confidence level. The method is simple, accurate, economical and can be applied for the determination of cadmium(II) in industrial wastewater samples.read more

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G A SHAR ,G A SOOMRO ,

Spectrophotometric Determination of Hg(II) as Complex with 8-Hydroxyquinoline in Micellar Medium

Spectrophotometric determination of mercury (II) is carried out with 8-hydroxy-quinoline as a complexing reagent in aqueous phase using cationic surfactant cetylpyridinium chloride (CPC). Beer’s law is obeyed over the concentration range 0.5-4.0 mg m1. The lmax molar absorption molar absorptivity and sandell’s sensitivity were 400 nm; emax = 0.75 x 104 mol-1dm3.cm-1 is 0.65 and (30.9) ng cm-2. Validation of this method has been made by comparing the results with those obtained by Atomic Absorption Spectroscopy (AAS) No significant difference was observed in the result obtained by the two methods at 95% confidence level. The method is simple, accurate, economical and can be applied for the determination of mercury (II) in industrial wastewater samples.read more

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G A SHAR ,G A SOOMRO ,

Spectroscopic and Electrochemical Studies on the Interaction Mechanism of Tetraploid (imidazole) Copper(II) Terephthalate with DNA

The crystal structure of tetraploid (imidazole) Copper(II) Terephthalate (Cu(Im)42+) was determined by X-rays crystallography. The interaction between DNA and the Cu(Im)42+ complex ions was studied by cyclic voltammetry, linear sweep voltammetry and UV/Vis spectroscopy. The results depicted an obvious decrease of the peak current with appositive shift of the peak potential in cyclic voltammogram after the interaction between the two studied species. The diffusion coefficient decreased. Hypochromicity was observed at 259 nm after the interaction of DNA and Cu(Im)42+. The competitive reaction of (Im)42+.and ethidium bromide (EB) confirmed that the interaction of DNA with (Im)42+. Complexion was intercalation.read more

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Z SHUSHENG ,N SHUYAN ,J KUI ,S XIN ,

Environmental Effect on Heavy Metals in Roadside Plants of Eucalyptus and Guaiacum officinale

Roadside plants (Eucalyptus and Guaiacum officinale) from controlled and polluted areas of Karachi city were analyzed for hevy8 metals. Leaves of these plants were taken for the study. Atomic absorption technique was employed for the analysis. Levels of Pb and Cu were found to be elevated in leaves of industrial and high traffic density areas. Rain was found to influence the metals concentration. Pb and Co levels increased while CU, Ni and Cd levels got decreased following rain. The collected data manifest that automobile exhaust and industrial wastes in urban areas of Karachi are causing pollution.  read more

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M F AHMED ,M A FARRUKH ,I I NAQVI ,

Nitrate/Nitrite Contamination in Groundwater of Karachi and its Correlation with other Physicochemical Parameters

A study on the contamination of groundwater by nitric and nitrite in residential areas of all the five districts of Karachi has been conducted. Samples have been analyzed for their different chemical constituents  and nitrate/nitrite content. The mean concentration of all the major chemical constitute like calcium, magnesium, sodium, potassium, chloride and sulfate were found to be particularly higher in groundwater samples of district south in the light of this study, groundwater samples of Karachi have been characterized as hard water. Nitrate contents were within the range 0.4-44.5 ppm as nitrogen and 75% samples have been found to be within permissible limits of WHO guidelines for nitrate, whereas nitrite contents were found to be below detection limits in 31% (10 out of 32) of samples, however the maximum i.e. 1.69 ppm as N was found in district South. Correlation coefficients have also been calculated, however no significant correlation has been found to exist between nitrate contents and other physicochemical parameters determined in this study.read more

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F A KHAN ,T H USMANI ,S N MAHMOOD ,I U SIIDDIUI ,S K ALVI ,

Study of Polymorphism in Calcium Halides Complexes of Pharmaceutically Important Ligands

The syntheses of calcium halides complexes of pharmaceutically important ligands have been reported. The ESR spectra have been measured at X- and Q-band, of manganese (II)  ions doped at a nominal 1% in the lattices of Ca (glycine)4 Cl2, Ca(accetamide)4 Cl2 and Ca(accetamide)4Br2. For the first time, in the ESR spectra of all these complexes, the Mn (II) ions have been found distributed between two lattice sites, suggesting the presence of two polymorphic forms for each of the complex. Further, in each case the polymprphic form with lower D value was always found to be formed in larger quantity than with higher D value. read more

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D M L GOODGAME ,MARGARET GOODGAME ,I HUSSAIN ,