VOLUME 32, NO4, AUG 2010

Thermodynamics and Kinetics of Adsorption of Dyes from Aqueous Media onto Alumina

Use of alumina for the removal of industrially important dyes namely, methylene blue, methyl blue, bromophenol blue, malachite green, eriochrome black-T, phenol red and methyl violet from aqueous media at different shaking times, temperatures and pH values has been investigated. The adsorption data was fitted to both the pseudo-first-order and pseudo-second-order kinetic models and calculated values of amount adsorbed at equilibrium (qe) by pseudo-second-order equations were found to be in good agreement with the experimental values. The negative values of ΔH and ΔG indicates that the adsorption is exothermic and spontaneous, respectively. The adsorption data was fitted to Freundlich, B.E.T., Dubinin-Radushevich (D-R) and Langmuir isotherms and their corresponding adsorption parameters for each were calculated. The dyes were found to be chemisorbed onto alumina.read more

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Muhammad Naeem Ashiq ,

Adsorption of Cadmium (II) by Chitin

The feasibility of using chitin as an adsorbent for cadmium (II) was examined. The adsorption characteristics were studied as a function of solution pH, temperature, contact time et. al., Maximum uptake amount of cadmium (II) was estimated to 93.9 mg/g·chitin by saturated capacity method at pH 5.41 in the HAc-NaAc system. The isotherm data for cadmium (II) at pH 5.41 fitted well to a Langmuir equation with a sorption capacity of 94.3 mg/g·chitin which was in accordance with the maximum uptake amount by means of the saturation method. The apparent adsorption rate constant was k288K = 3.34×10-5s-1, k298K = 4.60×10-5s-1, k308K = 6.35×10-5s-1 and k318K = 9.89×10-5s-1. The apparent activation energy was 63.1 kJ/mol. Thermodynamic parameters, ΔG298K was calculated to be -19.5 kJ/mol, ΔH and ΔS were found to be 10.6 kJ/mol and 101 J/mol·K, respectively. Adsorption mechanism was also proposed using infrared spectroscopy technique(IR).read more

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Chunhua Xiong ,

Evaluation of Nitrogen Uptake Patterns in Spring and Winter Wheat in Western Oregon

An understanding of the ground nitrogen (N) uptake pattern for wheat (Triticum aestivum L.) is essential to facilitate nitrogen management. The purpose of this study was to determine the nitrogen uptake pattern of spring and winter wheat grown in western Oregon, USA. Data used in this study were obtained from three different trials. For spring wheat rotation trials five spring wheat cultivars were used. Fertilizer N (16-16-16-4) at the rate of 140 kg ha-1 was applied at the time of planting. In small plot rotation trials five fertilizer treatments - 0, 50, 100,150 and 200 kg N ha-1 - were used. Rotations include winter wheat following clover and winter wheat following oat. The N uptake and dry matter yield of winter wheat were also determined from unfertilized plots of wheat trial. The maximum N uptake for spring wheat and winter wheat were at 1100 and 2000 accumulated growing degree days (GDD), before Feekes 10, respectively. The maximum N uptake rate for spring wheat, 0.038 kg N GDD-1, occurred at 750 GDD and the peak N uptake was observed approximately 35 days after Feekes 2. Nitrogen uptake in winter wheat was significantly affected by rotations.read more

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Mohammad Ayaz Khan Malghani ,

Mixed Ligand Copper(II) Complexes of Pyrrolidinedithiocarbamate and Diamines

Copper(II) complexes of pyrrolidinedithiocarbamate (PDTC) and diamines having the general formula, [Cu(diamine)(PDTC)]Cl, [Cu(diamine)Cl2][Cu(PDTC)Cl] or [Cu2(di-amine)(PDTC)2Cl2] (diamine = 1,3-diaminopropane, N,N/-dimethylethylenediamine, N,N,N/,N/-tetramethylethylenediamine and 1,2-phenylenediamine) have been prepared and characterized by IR spectroscopy and thermal analysis. The results of thermal analysis are consistent with the proposed composition of the complexes. The IR data suggest that coordination of the pyrrolidinedi-thiocarbamate (PDTC) takes place through the two sulfur atoms in a symmetrical bidentate fashion.read more

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Saeed Ahmad ,

Novel Ru-Complex of Methyldiphenylcyclopentadienylide

Ylide CpPMePh2 was synthesized by the deprotonation of Ylide salt of iodide by using different deprotonating agent like n butyl Li, NaH, (CH3)2N Li, isopropyl Li and ((CH3)3Si)2N.Li.  Out of all these deprotonating agents only ((CH3)3Si)2N.Li gave pure and better yield.  Its complex of Ru was synthesized. A RuCl2(PPh3)3 complex reacted with the freshly synthesized Ylide gave successful required ruthenium complex.  The synthesized [Ru(PPh3)3(CpPMePh2)2]Cl2 complex was analyzed and verified by 1H and 31P NMR.read more

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Syeda Robina Gilani ,

Antibacterial, Antimalarial and Leishmanicidal Activities of Cu (II) and Nickel (II) Complexes of Diclofenac Sodium

Metal complexes are famous for a wide array of chemotherapeutic effects. The current study was designed to synthesize and evaluate unexplored chemotherapeutic effects of Cu (II) and Nickel (II) complexes of the non-steroidal anti-inflammatory drug diclofenac. Nickel complex exhibited significant leishmanicidal activity against Lieshmania major, while the copper complex was found to possess low activity against the same pathogen. Both of the complexes revealed low antibacterial activities and were interestingly failed to produce any considerable antimalarial activity against Plasmodium falciparum 3D7. Selective leishmanicidal activities of Nickel (II) complex of diclofenac needs further improvement to be developed as potential new metal-based leishmanicidal agent.read more

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Fazal ur Rehman ,

Compettition of Aluminium on Iron Binding Site in the Biological System

Aluminum toxicity has been recognized in many ways, when exposure to heavy metals is prolonged, renal function is limited or a previously accumulated bone burden is released in stress and illness. Aluminum is generally found in +3 oxidation state, so sometimes it competes for the binding sites of Fe(III) in the biological system. If the concentration of Aluminum exceeds above the normal, it inhibits the absorption of Iron and Iron deficiency leads to diseases such as Parkinson's and Alzheimer. The complex formations of Al(III) and Fe(III) with salicylic hydroxamate were studied potentiometrically at different temperatures and data were subjected to computer programs. The stability constant (log β) values and thermodynamic stabilities were calculated. It was found that salicylic hydroxamate forms 1:1 complex at pH 3 and 1: 2 complex at pH 4 with Al(III) and Fe(III), respectively. The stability constant (log β) and thermodynamic stabilities of Al(III) salicylic hydroxamate complexes are close to Fe(III) salicylic hydroxamate complexes.read more

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Fouzia Sultana Rehmani ,

Analysis of Toxic Heavy Metals in Branded Pakistani Herbal Products

The present study was designed to estimate the concentration of heavy toxic metals in Pakistani herbal products frequently used for the treatment of various ailments. For this purpose, twenty five herbal products of well reputed herbal manufacturers were selected. The results of our investigation revealed that the concentrations of lead, cadmium, nickel and chromium were far beyond the permissible limits proposed by the International Regulatory Authorities for herbal drugs. Therefore, this study conveys a strong message to the ministry of health to establish proper rules and regulations for the validation of herbal products on scientific grounds in order to protect the general public from the harmful effects of these heavy metals in herbal products.read more

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Muhammad Saeed ,

Property of Novel Sodium Ion Exchanger Li1.4Cr0.2Al0.2Ti1.6(PO4)3

A novel sodium specific kind of ion exchanger Li1.4Cr0.2Al0.2Ti1.6(PO4)3 fabricated by a solid-state reaction method. The microstructure XRD, FTIR, Raman spectra, adsorption performances were investigated. The average grain size of the samples was about 70~90 μm. FTIR and Raman spectra studies were carried out and the vibrational bands were assigned. XRD analysis showed that the structure of Li1.4Cr0.2Al0.2Ti1.6(PO4)3 convert to Na1.4Cr0.2Al0.2Ti1.6(PO4)3 after adsorption. The exchange capacity reaches 34.12 mg/g, under adsorption duration 12 h, temperature 50 ?. The experimental results showed that the Na/Li ion exchange reaction rate increased obviously for Li1.4Cr0.2Al0.2Ti1.6(PO4)3 with increasing temperature, and the Na/Li ion exchange kinetics process of Li1.4Cr0.2Al0.2Ti1.6(PO4)3 in lithium chloride solution could be represented approximately by the equation of JMAK.read more

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JIAN- ZHI SUN ,

Chemical Activation of Bagasse Ash in Cementitious System and its Impact on Strength Development

The production of bagasse ash from sugar mills in a great quantity has become one of the environmental problem, but its use in cement mortar that provided a satisfactory solution to problems that associated with waste management. In this study, the effect of industrially produced quicklime on the strength development and pozzolanic reaction rates of Bagasse ash/Cementitious systems was investigated. Strength development of the Quicklime-Bagasse ash-Cement (C-BA-QL) system was monitored and presented here. Moreover, new efficiency factors were calculated for the activated systems in an attempt to seek for the optimum quicklime addition in each case. The addition of quicklime increased both the early and later strengths of the cement-bagasse ash specimens. A 3% addition of quicklime was found to be the optimum dosage for both short and longer curing periods.read more

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Noor ul Amin ,