VOLUME 33, NO4, AUG 2011

Comparative Studies for the Adsorption of Remazol Blue on Rice Husk, Saw Dust and Charcoal

Rice husk and saw dust are attempted as alternate adsorbents to charcoal for the removal of reactive dye, namely remazol brilliant blue from aqueous media. The adsorption of remazol brilliant blue has been studied onto rice husk, saw dust and charcoal at different shaking times, adsorbent dosage, temperatures and pH values and their results are compared. The adsorption data was fitted to Freundlich and Langmuir isotherms and corresponding adsorption parameters for each were calculated.  Pseudo first and second order kinetic models were used to calculate the amount adsorbed at equilibrium (qe). The calculated values of qe for pseudo-second order equation were found to be in good agreement with those of experimental values. The monolayer capacity (Vm) for rice husk (0.699 mg g-1) is greater than that for charcoal (0.074 mg g-1) and saw dust (0.114 mg g-1). It is concluded that rice husk is found better adsorbent for the removal of remazol brilliant blue as compared to charcoal and saw dust.read more

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MUHAMMAD NAEEM ASHIQ ,HAFIZ BADARUDDIN AHMAD ,MUHAMMAD YOUSAF ,MUHAMMAD ALEEM ,TAHIR ANWAR ,

Structure and Microstructure Studies of Epoxy Coating After Natural Exposure Testing

In this work, visual evaluation, Scanning electron microscopy (SEM)/energy dispersive X-ray (EDX) analysis and Fourier transform infrared (FTIR) spectroscopy were used to study the degradation of an epoxy coating system applied on mild steel test panels (10cm x 15cm) exposed at two natural exposure test sites. After surface preparation and application of coating, test panels were subjected to natural exposure at industrial and urban test sites located in Karachi, Pakistan. Visual evaluation showed that the major modes of degradation were totally different at two natural exposure test sites. Scanning electron microscopy (SEM) revealed that the testing caused changes in the surface morphology of the epoxy coating systems with natural exposure testing at urban site showing less surface degradation. Good correlation was observed between the SEM and gloss measurements. Energy dispersive X-ray (EDX) analysis indicated the increase in oxygen content and O/C (oxygen/carbon) ratio for exposed coatings as compared to unexposed coating. Increase in O/C ratio showed that the photodegradation of the coatings occurred upon weathering. EDX analysis is in good agreement with the fourier transform infrared (FTIR) spectroscopy results. Both observations indicated a high chemical degradation in the epoxy coating system tested at industrial exposure test site. Photodegradation of the epoxy coating system caused chain scission and as a result loss in intensity of the C-O stretching vibration of aryl ether near 1250cm-1 and C=C stretching of aromatic nucleus in the region of 1500-1600cm-1 were observed.read more

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SYED ARIF KAZMI ,HUMAIRA BANO ,MAZHER I. KHAN ,

Theoretical Studies on Membrane-Based Gas Separation using Computational Fluid Dynamics (CFD) of Mass Transfer

A 2D mass transfer model was developed to study carbon dioxide removal by absorption in membrane contactors. The model predicts the steady state absorbent and carbon dioxide concentrations in the membrane by solving the conservation equations. The continuity equations for three subdomains of the membrane contactor involving the tube; membrane and shell were obtained and solved by finite element method (FEM). The model was based on “non-wetted mode” in which the gas phase filled the membrane pores. Laminar parabolic velocity profile was used for the liquid flow in the tube side; whereas, the gas flow in the shell side was characterized by Happel’s free surface model. Axial and radial diffusion transport inside the shell, through the membrane, and within the tube side of the contactor was considered in the mass transfer model. The predictions of percent CO2 removal obtained by modeling were compared with the experimental values obtained from literature. They were the experimental results for CO2 removal from CO2/N2 gas mixture with amines aqueous solutions as the liquid solvent using polypropylene membrane contactor. The modeling predictions were in good agreement with the experimental values for different values of gas and liquid flow rates.read more

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AZAM MARJANI ,MEHRAN DAVALLO ,SAEED SHIRAZIAN ,MAHMOUD REZA SOHRABI ,SADEGH MORADI ,

Stabilization of Hydrogen Peroxide used as Oxidizi

H2O2 was used as oxidizing agent of the insoluble tetravalent uranium into the soluble hexavalent state along with NH4HCO3 as complexing agent in tap water solvent. The study was conducted to look at the possibility of commercial scale insitu leaching of uranium from an underground arkosic sandstone ore deposit. It was found that the peroxide was unstable in the basic tap water solvent as well as in the lixiviants to be used for uranium leaching, especially, in the presence of Ca ions and NH4HCO3. The rate of dissipation of the oxidizing agent was studied in different media at room temperature for 192 hours with distilled water as a reference medium. The material was stabilized by complexing the different ions / metal catalysts in the lixiviant by EDTA. In the presence of EDTA the stability behaviour of the peroxide became almost identical in the distilled water and tap water lixiviants.read more

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YAHYA KHAN, ABBAS KHAN, SYED SAKHAWAT SHAH, GULZAR HAMID, GULRAIZ FATIMA AND MUHAMMAD SIDDIQ

Studies on Contamination Level of Aflatoxins in Pakistani Rice

Aflatoxins (AF) are highly toxic and carcinogenic secondary fungal metabolites and have been detected in various food commodities including cereals. Rice samples collected during 2008–2009 were analyzed for aflatoxin B1 (AFB1), aflatoxin B2 (AFB2), aflatoxin G1 (AFG1) and aflatoxin G2 (AFG2) by thin layer chromatographic (TLC) technique. In total, 40 rice samples were collected and after dividing samples to sub-samples, AF analyses were carried out. AFB1 was detected in 28 samples (70 % of the total). The mean of AFB1 was 3.7ng/g for all samples. Total AF (AFT) was detected in 28 samples (70 % of the total). The mean of AFT was 4.9ng/g for all samples. AFB1 levels in 20 samples were below the maximum tolerated level (MTL) of AFB1 (2ng/g). Regarding AFT, the mean contamination level (4.9ng/g) was higher than the EU maximum permissible level for AFT (4ng/g).read more

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JAVED ALI ,ARSHAD HUSSAIN ,SHAFQAT ULLAH ,

Antibactericidal Effect of Some Substituted-1, 2, 4-Triazole Derivatives

The syntheses of a series of some substituted-1, 2, 4-triazole derivatives are described.  The reaction of sodium salt of α-sulphonated of stearic acid hydrazide (1) with carbon disulphide in alcoholic KOH yielded the corresponding sodium 1-(4-amino-5-mercapto-4H-[1, 2, 4]-triazol-3yl)-heptadecane-1-sulfonate (2). The reaction of compound (2) with urea, chloroacetyl chloride, chloroacetaldehyde and phenacyl bromides yielded the substituted 1, 2, 4-triazole derivatives (3), (4), (5) and (6) respectively. All the synthesized compounds were characterized by IR, PMR, Mass spectral data and elemental analyses. All newly synthesized compounds have been assayed for their antibacterial activities against S. aureus, E. coli, B. subtilis and P. aeruginosa.read more

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RAM JANAM SINGH ,

Mercury Concentration in Vegetables of Pakistan Irrigated by Different Water Sources

Mercury levels were determined in twenty samples of each vegetable i.e., Spinach (Spinacia oleracea), Lettuce (Lactuca sativa), Carrot (Daucus cariota), Capsicum (Capsicum fistulosus), Sweet pea (Lathyrus Odoratus), Potato (Solanum tuberosum) and Cabbage (Brassica oleracea), with a special reference of source of water of irrigation, i.e., tube well water, canal water and municipal sewage water. All the samples of vegetables were collected during the year 2006, 2007 and 2008 from the five districts of Pakistan viz Lahore, Kasur, Multan, Bahawalpur and R.Y.Khan. Statistical analysis such as Test of significance and multiple comparison were applied on the data obtained. The results showed that the concentration of Mercury in vegetables irrigated by canal water, sewage water and tube well water was in the range of 3.1-88.9 ppb and 9.0-130.6 ppb. It can be concluded from this study that the uptake of mercury by vegetables collected from above five districts of Pakistan was in the following order. Leafy vegetables > Root vegetables > seedy vegetables.read more

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ZAID MAHMOOD ,MUHAMMAD IMRAN ,ILYAS AHMED FARIDI ,SYEDA ROBINA GILLANI ,QAMAR SHAHEEN ,

Analysis of Heavy Metals in Selected Medicinal Plants from Dir, Swat and Peshawar Districts of Khyber Pakhtunkhwa

Essential and non-essential heavy metals like Manganese, Zinc, Iron, Nickel, Copper, Chromium, Lead and Cadmium were analyzed quantitatively in selected medicinal plants including, Acorus calamus, Artemisia annua, Chenopodium foliosum, Cupressus arizonica, Euphorbia helioscopia L, Lepidium sativum, Nerium oleander, Ranunculus mariculatus , Tecoma stans, Urtica dioica by using atomic absorption spectrometry. The main purpose of this study was to quantify essential and non-essential heavy metals in selected herbs, which are extensively used in the preparation of herbal products and standardized extracts. The high conc. of iron, Mn was found in Nerium oleander26.52 mg/kg, 94.40 mg/kg. Zn in Lepidium sativum 77.00 mg/kg and high conc. of K 94600 and Na 400 mg/kg was found in Tecoma stans. The concentration of other heavy metals particularly Cu, Ni and Pb were also found in higher conc. in the selected herbs. The main purpose of the present study was to evaluate the contents of toxic metals and their concentration level which may have adverse effect on human health, besides providing a scientific data.read more

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FARMAN ULLAH KHAN ,MUNEEB UR REHMAN KHATTAK ,FARHAT ALI KHAN ,INAYAT UR REHMAN ,IQBAL HUSSAIN ,FARID ULLAH KHAN ,

Comparative Studies of Heavy Metals in Wheat Growing in Different Environmental Conditions

In the present investigations, we screened wheat crops, collected from different areas of Peshawar and found that the level of heavy metals like Zn, Cu, Cr, Mn Cd, Ni, Pb and Fe in crop increases parallel to the extent of pollution. Wheat crop irrigated with industrial effluents accommodate high levels of heavy metals than those irrigated with municipal sewage and irrigated with tube well water. The aim of the study is to aware the public of the possible contamination and ensure that they avoid consumption of crops if grown near industrial dumps or other heavily contaminated places.read more

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IQBAL HUSSAIN ,MURAD ALI KHAN ,KAWAD ALI ,

Extraction-Spectrophotometric Determination OF Cadmium(II) by High Molecular Weight Amine. Application to Industrial Effluents

An investigation of the complex formation between Cadmium(II) and Potassium iodide in Sulphuric acid solution has been carried out and its extractability by high molecular weight tertiary amine (HMWA) in organic solvent was examined. The yellow colored complex of Cd(II)-I2 is quantitatively extractable into organic phase containing tribenzyle amine. On the basis of this extractability a method has been developed for the spectrophotometer determination of Cadmium in the presence of many other interfering radicals. The extractability of the Potassium iodide complex by HMWA suggests that the colored species is anionic.read more

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SHIREEN TAJ ,HAJRA MASOOD ,M ISHAQ ALI KHAN ,