VOLUME 31, NO5, OCT 2009
123
 
Surface Area and Pore Size Distribution of Activated Carbon Produced from Low Cost Precursors

Sultan Alam ,

Fast growing wood (Paulownia tomentosa-PT, Ailanthus altissima-AA, Salvadora oleoides-SO) and animal bones were utilized for the preparation of activated carbon. The carbon samples were activated and by thermal means (400-1000°C). The samples were characterized by surface area (Langmuir and BJH) with micropore and mesopores volume (BJH). The surface area of other carbon samples activated at 800 oC was found in the sequence: 654.9 for Salvadora oleoides > 615.8 for Ailanthus altissima > 346.3 for Paulownia tomentosa > 300.0 for animal bones. BJH surface area (m2g-1) analysis of the carbon samples activated at 800 oC was found in the sequence: 274.6 for Salvadora oleoides > 261.76 for animal bones > 224.8 for Paulownia tomentosa > 200.2 for Ailanthus altissima. The micropore volume (BJH method) of 800 oC activated carbon samples were in the sequence: 0.15 for Ailanthus altissima > 0.13 for Salvadora oleoides > 0.08 for animal bones.
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Micellization of Dodecyl Benzenesulfonic Acid and its Interaction with Poly(Ethylene Oxide) Polymer

mohammad saleem khan ,

The interaction between dodecyl benzene sulfonic acid (DBSA) with poly (ethylene oxide) (PEO) has been investigated at 293 K by conductance and surface tension measurements. The effect of concentration on the electrical conductance of DBSA in solution itself from 293-323 K above and below the Critical Micelle Concentration (CMC) was also studied. A number of important parameters i.e. critical aggregation concentration (CAC), Gibb’s free energy (DG) and binding ratio (R) was also determined. The effect of NaCl on the CAC and Polymer saturation point (PSP) was also investigated. It was found that conductance of PEO increased with the introduction of DBSA
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Oxidation of CO by O2 over ZnO Studied by FTIR Spectroscopy

ghulam hussain ,

The adsorption of CO at room temperature on finely divided ZnO surfaces, studied by FTIR, shows reversible bands (2250-2050 cm-1) and irreversible absorption bands (1800-600 cm-1). The irreversible absorption bands (1800-600 cm-1) are assigned to various species such as bi- and monodentate carbonates. The band position of the reversibly adsorbed species depends on the extent of the surface carbonates, formed by the oxidation of CO. The order of introduction of CO and O2 and whether the ZnO surface is oxidised or reduced, gave significantly different results in terms of species formed from irreversible adsorption. The strongest carbonate formation occurred on heating to 185 °C after O2 was added to the pre-adsorbed CO on an oxidised ZnO surface at room temperature followed by heating to 185 °C in the presence of the two-gas mixture.
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Identification of Radiation Treatment of Frozen Chicken and Fresh Turkey using DNA Comet Assay

hasan mahboob khan ,

DNA comet assay was applied to check the detection of radiation treatment of frozen chicken and fresh turkey. The cells from unirradiated and irradiated samples of chicken and turkey were extracted in cold PBS, embedded in agarose on microscope slides, lysed for 15 minutes in 2.5 % SDS and subjected to electrophoresis at a rate of 2V/cm for 2 minutes. After silver staining these slides were evaluated through an ordinary transmission microscope. In irradiated samples, fragmented DNA (due to radiation treatment) stretched towards the anode and cells appear as comets. The density of DNA material in the tails increased with increasing radiation dose. However in case of unirradiated samples, the large molecule of DNA remained relatively intact and there was only minor or no migration of DNA; thus cells were round or had very short tails. Therefore, clear discrimination between unirradiated and irradiated food samples is possible. Hence, DNA comet assay provides an inexpensive and quick screening method for several kinds of foods containing DNA including frozen chicken and fresh turkey.
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Effect of the Hydrophilic Block Length on the Surface-Active and Micellar Thermodynamic Properties of Oxyethylene-Oxybutylene Diblock Copolymers in Aqueous Solution

Muhammad Siddiq ,

The effect of hydrophilic block length on the surface and micellar thermodynamic properties of aqueous solution of E40B8, E80B8 and E120B8 diblock copolymers, were studied by surface tension measurements over a wide concentration and temperature range; where E stands for an oxyethylene unit and B for an oxybutylene unit. Like conventional surfactants, two breaks (change in the slope) were observed in the surface tension vs logarithm of concentration curve for all the three copolymers. Surface tension measurements were used to estimate surface excess concentrations (Γm), area per molecule at air/water interface and thermodynamic parameters for adsorption of the pre-micellar region in the temperature range 20 to 50 ºC. Likewise the critical micelle concentration, CMC and thermodynamic parameters for micellization were also calculated for the post-micellar solutions at all temperatures. For comparison the thermodynamic parameters of adsorption and micellization are discussed in detail. The impact of varying E-block length and temperature on all calculated parameters are also discussed. This study shows the importance of hydrophobic-hydrophilic-balance (HHB) of copolymers on various surface and micellar properties.
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Determination of Activation Energy for the Degradation of Rhodamine B in the Presence of Hydrogen Peroxide and some Metal Oxide

abbas mehrdad ,

In this research, degradation of rodamine B in the presence of (hydrogen peroxide), (hydrogen peroxide+aluminum oxide), (hydrogen peroxide+nano-sized aluminum oxide) and (hydrogen peroxide+iron oxide) was curried out at various temperatures (20, 25, 30, 35 and 40 ºC) to calculate activation energy. The activation energy for degradation of rodamine B in the presence of (hydrogen peroxide), (hydrogen peroxide+aluminum oxide), (hydrogen peroxide+nano-sized aluminum oxide) and (hydrogen peroxide+iron oxide) in studied rang were calculated 40.71, 33.75, 30.72 and 36.60 kJ.mol-1, respectively
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Mixed Complex Combinations with a New Schiff Base used as Membranes Ion-Selective for Copper and Nickel Ions; Analytical Applications

liviu mitu ,

Four electrodes with liquid membrane, Cu2+-selective and Ni2+-selective, not previously described in the literature, were prepared and characterized. Electrodes 1 and 2 are based on mixed complexes of Cu(II) and Ni(II) with isonicotinoylhydrazone-2-aldehydepyrrole (INH2AP = HL1) as ligand and electrodes 3 and 4 are based on the mixed complexes with isonicotinoyl-hydrazone-2-hydroxy-1-naphthaldehyde (INH2HNA = H2L2). Cu2+- selective and Ni2+- selective electrodes have been used to determine the copper and nickel ions in aqueous solutions, by both direct potentiometric and potentiometric titration with EDTA. They have also been used for determining the Cu2+and Ni2+ ions in industrial waters by direct potentiometry. The analytical results obtained have been checked by the standard addition method and by comparison with determinations through atomic absorption spectrometry.
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Comparison of Two Extraction Methods for Metals from Atmospheric Particulate Matter

tauseef ahmad quraishi ,

Particulate pollution in ambient air of Lahore is a serious problem. Atmospheric particulates concentrations (PM10) were measured at the city centre during February to April 2007, which ranged between 465 and 806 µg/m3 with an average of 602 µg/m3, about an order of magnitude greater than the World Health Organization guideline value of 50 µg/m3. Metal and metalloid components of particles have been shown to be of greater health significance, especially the water soluble species.  A number of methods have been used to extract the total and water soluble species. In the present study one method each was evaluated for total and water soluble metals (cadmium, chromium, lead, nickel, and mercury), and metalloid species (antimony and arsenic). Segments from the same filter were used for the two methods. Concentrated acids with microwave digestion were used for total concentrations whereas water soluble species were extracted by shaking for 2 hours in one percent HCl solution. The latter method worked as well as the former for cadmium, lead, and antimony, giving about the same concentrations with good correlations.  However, for the remaining elements water soluble concentrations were generally lower than the strong acid extractions, indicating lower bioavailability of such elements. Majority of the values for total as well as water soluble cadmium and lead concentrations exceeded the WHO guideline values whereas for other elements the concentrations in both fractions were within acceptable limits.
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Effect of Time Intervals on Levels of Selected Heavy Metals in Surface and Ground Waters in Peshawar Basin

ihsan ihsanullah ,

During the last two decades, the high rate of industrialization, unplanned urbanization and heavy load of transportation resulted in a drastic increase in water pollution within the Peshawar basin in general and in the Peshawar metropolis in particular. The present study is based on the monitoring of heavy metals such as iron (Fe), copper (Cu),  lead (Pb), chromium (Cr), nickel (Ni), cadmium (Cd) and cobalt (Co) in surface and ground waters of the Peshawar basins, one of the largest basin of Pakistan, during the years 2003 and 2004. In order to evaluate the increase of the levels of these metals with the passage of time, the data obtained are presented. The results are also compared with the previous studies and the permissible limits set by US-EPA and WHO. The concentration of tested elements in the waters of most of the areas of Peshawar basin are within the permissible limit, but in certain areas, the concentrations of Fe, Pb, Cr and Ni are too high and pose a threat to the health of the people. Both anthropogenic and geogenic sources could be responsible for this contamination. The anthropogenic sources include the waste from the industrial estates and many tannery industries in Peshawar city and the corrosion of underground pipes, while the geogenic sources include the sulfide seams and mafic and ultramafic rocks in the northwest and northeast of the Peshawar basin.
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Assessment of Bioactivity of Cassia fistula Using Bombyx mori Lethality Assay

muhammad asif hanif ,

: In recent times, focus on plant research has increased all over the world and a large body of evidence is being collected to evaluate immense potential of medicinal plants used in various traditional systems. In this regard, the present study was conducted to evaluate the bioactivity of a commonly used medicinal plant Cassia fistula against newly selected Bombyx mori (silkworm) larvae. C. fistula pods were extracted using water, methanol, ethanol, hydro-methanol (1:1) and hydro-ethanol (1:1) and were assayed for their activity against Bombyx mori. Methanol extract of C. fistula at concentration of 100 mg/L killed half (LC50) of Bomyx mori larvae under study. Bomyx mori LC50 for other C. fistula extracts were 400 mg/L for ethanol and hydro-methanol, 800 mg/L for hydro-ethanol and 1600 mg/L for aqueous extract. From the results of the present study it can be concluded that Bombyx mori lethality bioassay can be considered a useful preliminary tool for plant extract toxicity evaluation. The main objectives of the present study was to develop a new and simple assay to evaluate claims from traditional, tribal and advanced medicinal lore to suggest directions for future clinical research and commercial importance that could be carried out by local investigators in developing regions.
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