VOLUME 31, NO6, DEC 2009
12
 
Environmental Pollution, A Threat to Photosynthesis in Healthy Plants

gulrez fatima durrani ,

Environmental pollutants, in atmosphere depend upon the source, strength, meteorological conditions and topography and effect the flora and fauna. Photosynthesis, which is the main necessity for plants to maintain their metabolic process, grow in size and for their reproduction, is directly or indirectly affected by manmade pollution. This synthetic pollution includes industrial discharge and vehicular exhaust, throws many toxic elements in air, water and soil in industrialized zone. To investigate this effect leave were collected from sunny, semi-shady and shady side of different trees at varying distance from industrial area and busy road and analyzed for various Photosynthetic pigments. The results show that average value of total chlorophyll varied in the range of 23-39mg/g, chlorophyll a, 5-19.6mg/g and b in the range of 5.6-20.3mg/g and carotene contents in the range of 17.6-41.3mg/g of the sample taken depending upon the type of the plant and the distance from industries and busy road. These values were in decreasing order of sunny > semi-shady > shady leaves. The concentration of all pigments increased as the distance from the industrial area and busy road increased. These values were comparatively lower as compared to the value in non-polluted areas. The soil and water samples from different sites around the trees in environmentally polluted and non polluted areas were also analyzed.
Pages(851)
Download
Ultrasound in Chemical Processes

Sofia Baig ,

The use of ultrasound to promote ‘chemical’ reactions or Sonochemistry is a field of chemistry which involves the process of acoustic cavitations i.e. the collapse of microscopic bubbles in liquid. There are two essential components for the application of sonochemistry, a liquid medium and a source of high-energy vibrations. The liquid medium is necessary because sonochemistry is driven by acoustic cavitations that can only occur in liquids. The source of the vibrational energy is the transducer. The chemical effects of ultrasound include the enhancement of reaction rates at ambient temperatures and striking advancements in stoichiometric and catalytic reactions. In some cases, ultrasonic irradiation can increase reactivities by nearly million fold. The ultrasound has large number of applications not only in emending old chemical processes but also in developing new synthetic strategies. Ultrasound enhances all chemical and physical processes e.g., crystallization, vitamin synthesis, preparation of catalysts, dissolution of chemicals, organometalic reactions, electrochemical processes, etc. High-power ultrasonics is a new powerful technology that is not only safe and environmentally friendly in its application but is also efficient and economical. It can be applied to existing processes to eliminate the need for chemicals and/or heat application in a variety of industrial processes.
Pages(857)
Download
Geochemical Investigation of Crude Oils from Different Oil Fields of the Potwar Basin

tahira fazeelat ,

Crude oils (12) from the Potwar Basin, have been analyzed to obtain geochemical information on source and depositional environment of organic matter, maturation, biodegradation and geochemical correlation. Bulk and molecular parameters have recognized three groups of petroleum within the study area, Group I of heavy oils, Group II of medium to light oils and Group III, comprising of a single oil Adhi, of light oil. Based on samples location in ternary diagram, Group I oils were classified as paraffinic naphthenic (PN), while Groups II and III were classified as paraffinic (P) oils. Gas chromatographic (GC) fingerprints of Group II and III oils showed full suite of n-alkanes, low isoprenoid to n-alkane (Pr/nC17 and Ph/nC18) ratios, absence of UCM (unresolved complex mixture) and higher saturates/aromatics ratios. These features suggested non-biodegraded nature of these samples. Most of the oils of Group I were affected by light to moderate biodegradation on account of these parameters. Carbon Preference Index (CPI) and Odd Even predominance (OEP) 1.0 for Group II and Adhi and <1.0 for Group I oils revealed slightly lower thermal maturity of the latter. Terrestrial to aquatic ratios (TAR) suggested that all the samples contained mixed organic matter (OM) with predominant contribution of marine geolipids for Groups I & II and terrestrial OM for Group III. Pristane to phytane (Pr/Ph) ratios  £ 1 along with high sulfur content suggested typical marine carbonate dysoxic sediments generating Group I oils, while Pr/Ph > 1 and very low sulfur content recommended oxic depositional settings for Group I oils and Adhi. The differences in the location of Joyamair and Minwal on geochemical plots were interpreted to difference in thermal maturity compared to other oils of this group.
Pages(863)
Download
Synthesis and Characterization of Cu11V6O26 as High–Capacity Cathodes for Lithium Secondary Batteries via a Wet–Chemistry Route

xiaoyu cao ,

The cathode material of Cu11V6O26 has been synthesized for the lithium secondary batteries via the wet-chemistry method. The as-prepared powders were characterized by powder X-ray diffraction (XRD), scanning electron microscope (SEM) and laser particle size analysis (LPSA). The electrochemical performances were evaluated by the galvanostatic discharge-charge and cyclic voltammetry technique. These results revealed that Cu11V6O26 powder could be formed at a temperature as low as 300 °C, and its particle size was smaller and distributed in a narrower range compared to the other powders synthesized at 400 °C and 500 °C. The initial discharge capacity of the powder synthesized at 300 °C whose D50% was only 24.251μm was 318.2 mAh/g. It was also found that a severe structure modification of Cu11V6O26 powder might take place after the first cycle according to cyclic voltammetry test, which should be responsible for its irreversible capacity.
Pages(871)
Download
Removal of Cu (II) Ions from Aqueous Solutions by Turmeric Powder

Amtul Qayoom ,

Copper is an essential nutrient, but it is toxic at high intake levels.  The presence of copper(II) ions causes serious toxicological concerns, it is usually known to deposit in brain, skin, liver, pancreas and myocardium.  In this work the ability of turmeric to remove copper (II) ions from aqueous solution was studied. Adsorption of metals ions by turmeric powder may be used as a natural remedy for sequestration of toxic metals which are ingested through daily food intake.  It was found that adsorption increased with increasing contact time, pH, temperature, adsorbent dose. The equilibrium data were satisfactorily described by Freundlich isotherm model. Adsorption of Cu (II) by turmeric powder was followed by pseudo 2nd  order kinetics.
Pages(876)
Download
Synthesis and Characterization of Polyaniline/Wood and Polyaniline/Carbon Composites

farah kanwal ,

Conducting polymers have shown many applications in the field of nanoscience, nanotechnology and nuclear science. Polyaniline (PANI) is the most studied conducting polymer due to its environmental stability, easy availability of its raw materials, and simple synthesis. We have synthesized polyaniline and two of its conducting composites i.e., polyaniline-carbon and polyaniline-wood in acidic medium (HCl) using K2Cr2O7 as oxidizing agent. All samples were characterized by FTIR and four-probe d.c. conductivity methods. The synthesis was carried out at two different temperatures (0 °C and -5 °C) and it was found that the yield and conductivity were maximum at lower temperature (-5 °C). The polyaniline-carbon composites showed enhanced conductivity whereas polyaniline-wood composites showed reduced conductivity when compared with the conductivity of pure polyaniline.
Pages(882)
Download
Vibrational Spectroscopic Investigation of Some Hofmann-Td Type Complexes: Ni(1-Phenylpiperazine)2M(CN)4 (M = Cd or Hg)

cemal parlak ,

New Hofmann-Td type complexes in the form of Ni(pp)2M(CN)4 (where pp =              1-Phenylpiperazine and M = Cd or Hg) have been prepared in powder form and their infrared (4000-100 cm-1) and Raman (2800-1650 cm-1) spectra have been reported. The results suggest that these compounds are similar in structure to the Hofmann-Td type complexes, in which the M atom is tetrahedrally coordinated to the carbon atoms of the four cyanide groups, while the Ni atom is octahedrally surrounded by six nitrogen atoms, two of which are from pp ligands which have been coordinated as a unidentate ligand coordinating only through the NH nitrogen and the rest are from cyanide groups. In this host structure, the M(CN)4 groups have been linked by the Ni(pp)2 moieties to form a three-dimensional network.
Pages(888)
Download
Synthesis and Spectroscopic Studies of Some Novel 4-Substitued -Diketo-Anils in Free and in Coordinated Forms

syeda rubina gilani ,

The Schiff bases of activated anilines with b-diketone have been synthesized.  The electron donating effects of methyl, methoxy and chloro groups, before and after coordination, were studied with the help of vibrational spectra and supported by UV-vis studies.  In these b-diketo-anils and their complexes, instead of a band in the region 1590–1620 cm-1 for C=N group, bands in the regions 1100–1300 cm-1 and 3100–3300 cm-1 were observed and were assigned to C-N and N-H bonds.  No significant band appeared for C=N in any of these ligands either in free or in coordinated forms.  It was concluded that unlike other aldehydes and ketones, b-diketone upon reacting with anilines form C=C-N-H bonding instead of producing C=N functional group
Pages(894)
Download
Synthesis, Characterization and Metal Uptake Study of Cu and Cd on Poly-5, 5’- Methylene-bis-(2-Hydroxy Benzaldehyde) Ethylenediimine.

ambreen shah ,

The Schiff base polymer derived from ethylenediamine and 2-hydroxybenzaldehyde with formaldehyde (o-HBED-HCHO) formed chelates with Cu (II) and Cd (II) metal ions. The formation of Schiff base, resin and the polychelates were confirmed by C H N analysis, infrared, UV/Vis spectra and thermogravimetric analysis. The intrinsic viscosity of resin was determined by viscometry in THF. The adsorption characteristics of resin towards Cu (II) and Cd (II) metal ions in dilute solutions were measured, which indicated metal loading of Cu (II) 84.0 % and Cd (II) 70 % at room temperature on an optimized pH 6. The effects of pH optimization, flow rate, capacity of % sorption were studied. After these optimization the resin was examined for adsorption  of  both Cu (II) and Cd (II) metal ions from their aqueous solutions after desorption  and determination by atomic absorption spectrometry.
Pages(900)
Download
Synthesis and Characterization of Silver Hexacyanoferrate(II)/ Polyaniline Composites

farah kanwal ,

Silver hexacyanoferrate(II)/conducting polyaniline composite was synthesized in two steps process; In the first step, silver hexacyanoferrate(III) was synthesized by reaction of K3[Fe(CN)6] and AgNO3 solutions. In the second step, silver hexacyanoferrate(III) was reacted with aniline/HNO3 solution. Silver hexacyanoferrate(III) acted as an oxidant to polymerize aniline monomer. Silver hexacyanoferrate(II)/conducting polyaniline composite was prepared at different temperatures (37 OC, 27 OC, 17 OC) and in different concentrations of AgNO3 (0.4M, 0.8M, 1.2M) and HNO3 (1M and 2M). Silver hexacyanoferrate(II)/conducting polyaniline composite was characterized by FTIR and DC conductivity was measured by four probe technique. Conductivity of Silver hexacyanoferrate(II)/polyaniline composite was found to be increased with increasing temperature. However, conductivity decreased significantly with increasing concentrations of AgNO3 but remained unaffected with the change in  HNO3 concentration from 1-2 molar.  
Pages(907)
Download
12

 

Browse By Issue