VOLUME 30, NO6, DEC 2008

Batch Adsorption Studies of Cadmium in Wastewater on Bentonites

This study describes the batch adsorption process for the removal of cadmium from wastewater using natural bentonites taken from various areas of Pakistan. Bentonite contains montmorillonite, which has the quality to adsorb inorganic and organic materials. Relying upon atomic absorption spectroscopy, the quantities of toxic metals before and after the treatment of their standard solutions with different samples of bentonite were determined at room temperature and -200 mesh particle size. The percentage adsorption for cadmium on bentonite samples was determinedread more

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SHAHID TUFAIL SHEIKH ,KHALID JAVED ,NASEEM ZAHRA ,

Variations of Contaminants in the Road Side Agricultural Soil of Thana Malakand Agency

Agricultural soil samples were collected from the G. T. road side of Thana Malakand Agency, at various distances and were studied for different parameters. pH of soil samples was found in the range of 6.9 to 7.3 which is neutral in nature. Iron was found in the range of 5.8 to 40.45 mg/ L. At low level, iron causes chlorophyll deficiency. Nickel was in the range of (4.2 to 22.5 mg/ L) and is needed for the metabolism of plant nitrogen. Copper was found in the range of 6.55 to 25.41 mg/ L. Functions of copper include chlorophyll synthesis and protein metabolism.  Zinc was in the range of 8.41 to 50.23 mg/ L. Cadmium was found in the range 5.12 to 42.12 mg/ L, which is higher than the desirable level for fertile soil therefore it may cause diseases like wilting and red orange coloration of leaves. Lead was found 5.23 to 56.12 mg/ L. Manganese was found from 6.55 to 60.12 mg/ L. Manganese is essential for nitrogen and inorganic acid metabolism. The concentration of chromium was found in the range of 3.2 to 23.4 mg/ L. Concentration between 5-30 mg/ Kg is considered of critical importance for plants and deviation could cause yield reduction. The highest concentrations of metals were found in the sample S-1, which is near the main bazaar, decreasing gradually from S-1 to S-12. This may be due to the fact that different sources near the main bazaar contaminate the agricultural soil thus raising its concentrationread more

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ZIA UD DIN ,ILYAS KHAN AHMAD ,FAZLULLAH KHAN BANGASH ,SULTAN ALAM ,

Effect of Soil Contamination on Some Heavy Metals Content of Cannabis sativa

Heavy metals were investigated in the medicinal plant Cannabis sativa and the soil of the area from where the plant was collected using atomic absorption spectrophotometer. The plant samples were collected from five different locations of N.W.F.P, Pakistan. The plant parts including roots, stem and leaves were found to have the quantity of heavy metals corresponding to their contents in the soil. The purpose of the study is to make awareness among the people about the proper use and collection of medicinal plants, containing high level of heavy metals and their adverse health effects.read more

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SUHAIL NOOR ,SAEED AKHTAR ,FAREEDULLAH KHAN KHATTAK ,INAYAT UR RAHMAN ,MURAD ALI KHAN ,ABDUL WAJID ,

Electro-oxidation of Methanol on Fuel Cell Catalysts and Evaluation of their Catalytic Activities by Cyclic Voltammetry

The electro-oxidation of methanol on smooth Pt-strip and 10 % Pt supported on Vulcan XC-72 was studied in acidic medium using cyclic voltammetry. The electro-oxidation of methanol gave well-defined anodic peaks in both anodic and cathodic sweeps. Real surface area, roughness factor, exchange current density, peak current and the heterogeneous rate constant for electro-oxidation of methanol were found to be higher on 10 % Pt-catalyst as compared with smooth Pt-strip.  The thermodynamic parameters, ΔH*, ΔS* and ΔG298* were evaluated.  The value of ΔH* for electro-oxidation of methanol on smooth Pt-strip was higher and found 57 kJ mol-1, while the value of ΔH* on 10 % Pt-catalyst was 26 kJ mol-1. The more positive value of ΔH* obtained on smooth Pt-strip was attributed to its poor catalytic activity for electro-oxidation of methanol. The values of ΔG298* were also positive indicating that the electro-oxidation of methanol on fuel cell catalysts was an endothermic and non-spontaneous process and hence the higher temperature might be more favorable for increasing the catalytic activity of fuel cell catalysts.read more

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RIAZ AHMED ,ABDUL SATTARALI KHAN ,MOHAMMAD LATIF MIRZA ,

Analysis of Mixtures of Ferrocyanide and Ferricyanide using UV-Visible Spectroscopy for Characterisation of a Novel Redox Flow Battery

A novel Redox Flow Battery (RFB) was designed and developed at the University of Manchester.  This system eliminated the ion-exchange membrane altogether by employing porous flow through electrodes.  This system was characterised [1] using the ferrocyanide/ferricyanide [hexacyanoferrate (II)/hexacyanoferrate (III)] redox couple which had relatively fast electrochemical kinetics at several electrode surfaces.  In this study an accurate method had been developed to determine the concentrations of the ferrocyanide/ferricyanide species from samples obtained from the battery.  UV/Visible spectroscopy was chosen as the analytical tool for this purpose.  Analysis of a range of standard solutions showed that by measuring the absorbance 260 nm and 420 nm it was possible to determine the concentration of both ferrocyanide and ferricyanide ions in a mixture of the two active species.  Using the correlations developed, it was possible to determine the concentrations of ferrocyanide and ferricyanide ions to an accuracy of ± 4% in mixtures with concentrations in the range 0.01 to 0.1 mM.  In work reported elsewhere [1] this analytical method was used to characterise the Redox Flow Battery and it was found that high conversion (>90%) could be achieved at relatively high concentrations (0.1 M) of the active species.read more

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MOHAMMAD HARUN CHAKRABARTI ,EDWARD PELHANLINDFIELD ROBERTS ,

Determination of Redox Potential and Stability Constant of Iron(III)-3-Hydroxy-2-Methyl-4-Pyrone Complexes

Maltol (3-HYDROXY-2-METHYL-4-PYRONE) is a monobasic bidentate ligand for a number of metal ions. It forms a stable 5-membered chelate ring with the metal ions. Having a very low toxicity index it has found extensive use as a flavouring agent. Depending on the oxidation state of the metal ion and the metal to ligand stoichiometry, the complex ion can be uncharged or it may have a +1 or +2 charge. This study describes the results of a potentiometric study for the determination of stability constants and a spectrophotometric determination of pH dependent redox potential at pH 3.0, 4.0, 5.0 and 7.0 using ascorbate as a reducing agent. At 25o C, the results were: log b1 = 11.20,  log b2 = 21.90  &  log b3 = 28.20 and Eo complex (vs NHE) at pH 3.0 = 0.229; pH 4.0 = 0.144; pH 5.0 = 0.107; pH 7.00 = 0.0442. These results are interpreted in terms of efficacy of maltol for its proposed usage for different medical applications.read more

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SYED ARIF KAZMI ,SHABANA AMIN ,

Analysis of Flavonoids in Flos Genkwa by -cyclodextrin and Ionic Liquid Modified Capillary Zone Electrophoresis

A β-cyclodextrin (β-CD) and ionic liquid (1-ethyl-3-methylimidazolium tetrafluroborate, 1E-3MI-TFB) modified capillary zone electrophoretic (CZE) method has been developed to determine three flavonoids (genkwanin, apigenin and luteolin) in Flos Genkwa with 4-methylumbelliferone as internal standard. The effects of buffer pH and concentration, β-CD concentration and ionic liquid on separation were investigated. The optimum electrophoretic conditions are as follows: 20 mmol·L-1 tetraborate (pH 9.0)- 6 mmol·L-1 β-cyclodextrin-0.04 %  1E-3MI-TFB (V/V) as the running buffer, applied voltage of 25 kV. Under the optimized conditions, the calibration curves of the three flavonoids all showed excellent linearity in the 1~100 mg· mL-1 range. The relative standard deviation in migration time and peak area was 0.21 % and 2.92 % for genkwanin, 0.15 % and 2.33 % for apigenin, 0.28 % and 3.35 % for luteolin. The detection limits of the three flavonoids ranged from 0.26 to 0.32 mg?mL-1. The recoveries of the three flavonoids ranged between 94.3 % and 103.5 %read more

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YUMEI LI ,HUIXIN LI ,YUANQI LU ,

Flow Injection Spectrophotometric Determination of Total Iron in Fresh Waters using 1,10-Phenanthroline Reagent

A simple flow injection method is reported for the determination of total iron in fresh waters based on spectrophotometric detection of reddish orange iron (II)–1,10-phenanthroline  complex measured at wavelength 510 nm. The system permits high throughput of 120 samples per hour. A linear calibration (r2 = 0.9981) graph was obtained over the concentration range 0.2-1.0 mg L-1 with relative standard deviation (n = 4) 0.6-1.0 %. The limit of detection (3s blank) was 0.01 mg L-1. The proposed method has been applied successfully for the determination of iron in fresh water samples and the results obtained (0.04 ± 0.003-0.09 ± 0.01 mg L-1) were in reasonable agreement with the results obtained using a spectrophotometric method (0.05±0.008-0.1±0.005 mg L-1) as the reference method.read more

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AMIR WASEEM ,ATTIQ UR RAHMAN ,ABDUL NABI ,MOHAMMAD YAQOOB ,

The Effect of Temperature on the Uptake of Copper and Cadmium by Penaeid Shrimp

Penaeid shrimp (P .monodon and P. penicillatus) among dominant cultured shrimps were analysed to assess the uptake potentialities of copper and cadmium at different temperature.  It is observed that the survival is directly proportional to the intensity of temperature. Uptake of Cu at 25 °C on 100 μg/l exposure was to be 2.34-2.60 μg/g dry wt. and Cd was 1.56-1.65 μg/g dry wt. The concentrations of these metals determined by AAS at 30 °C and 40 °C were 8.45 μg/g and 7.20 μg/g for Cu and 7.25 μg/l and 6.27 μg/g of dry wt for Cd in P. monodon. The same amount was determined in P. Penicillatus respectively. The uptake of these metals increased with the increase in temperature and gradually variable at every larval stage of both species depending upon size of these specimens. The survival rate was found to be directly proportional to uptake of metals with increased  toxicity of copper and cadmium.read more

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FAYYAZ AHMAD ANSARI ,HINA ASGHAR SIDDIQI ,ALIA BANO MUNSHI ,

Variation in Physico-Chemical Constituents and Lipid Composition Among Arachis Hypogea Cultivars

Four cultivars of ground nut (Arachis hypogea) were collected from different areas of Pakistan (Tillagang, Gujar Khan). The oils were extracted for the evaluation of lipid. The physico-chemical values of oils were determined like refractive index, peroxide value, unsaponifiable matter, acid value, iodine value, free fatty acid and ester value. The lipid profile as indicated by GLC showed that palmitic acid ranged from 8. 2-8.8 %, proportions of oleic acid and linoleic acid varied from 57.8-59.87 % and 22.5-24.1 % respectively. Gujar Khan variety of peanut has higher % age of oil (56.79). The higher yield of oil in this variety is not at the cost of any nutritional quality of peanut oil.read more

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SHAHNAZ HAMID ,HIFZA AKHTAR ,