VOLUME 36, NO6, DEC-2014

Synthesis and Characterization of Soluble and Thermally Stable Polypyrrole-DBSA Salts

In the present study, an attempt has been made to synthesize soluble PPy via inverse emulsion polymerization pathway using benzoyl peroxide as an oxidant and dodecylbenzenesulfonic acid (DBSA) as dopant as well as a surfactant. A mixture of chloroform and 2-butanol was used as dispersion medium for the first time. Pyrrole polymerized into PPy inside the micelle under these conditions. The influence of synthesis parameters such as amount of pyrrole, benzoyl peroxide (BPO) and DBSA on the percent yield and other properties of the resulting PPy was studied. The synthesized PPy was found to be completely soluble in DMSO, DMF, THF, chloroform and m-cresol etc. The structure of PPy and incorporation of DBSA in the polymer backbone was confirmed by FT-IR. UV-Vis spectra of PPy showed correspondence with the electrical conductivity of the prepared salts. SEM micrographs showed the typical granular morphology of PPy-DBSA. TGA and XRD of the prepared PPy samples were also studied and explained.read more

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Salma Bilal, Mohammad Sohail and Anwar-ul-Haq Ali Shah

Gamma Radiolytic Degradation of Heptachlor in Methanol and Monitoring of Degradation by HPLC

Removal of known insecticide Heptachlor (HPTC) in methanol solution by γ-rays under varied experimental conditions has been optimized. Air saturated solution of HPTC was irradiated at γ-rays dose from 1 to 10 kGys. The extent of radiolytic degradation was monitored by reversed phase high performance liquid chromatography (HPLC) coupled with UV detector. At dose of 10 kGys ≥ 98 % of HPTC was degraded. The degradation of HPTC occurs by CH3O• and •CH2OH radicals generated by methanol radiolysis. It is concluded that γ-rays can remove Persistent Organic Pollutants (POPs) form environmental matrices. It can decrease the harmful properties of these POPs by their transformation into less resistant fragments to biological / natural elimination in the aquatic atmosphere.read more

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Muhammad Riaz and Shahid Bilal Butt

Novel Spectrophotometric Methods for Determination ofSalicylamide and Ascorbic acid in their binary mixture

Simple, selective and precise four spectrophotometric methods were developed and validated for quantitative determination of Salicylamide (SAD) and Ascorbic acid (ASC, Vitamin C) in their binary mixture. Method A is Area under curve spectrophotometry, in which the area under curve in the wavelength ranges 225-245 nm and 265-285 nm were selected for determination of SAD and ASC. Method B is based on dual wavelength spectrophotometry, where ASC can be determined by difference in absorbance at 249.8 and 285.8 nm. On the same way; SAD is measured by difference in absorbance at 240.4 and 286.4 nm. Method C utilizes isoabsorptive point spectrophotometry where total concentration of SAD and ASC was calculated at their isoabsorptive points at 246.4 and 287 nm, while SAD concentration alone can be determined by first derivative spectrophotometry (1D) at 315.4 nm, then ASC concentration can be determined by subtraction. Method D is ratio subtraction spectrophotometry, where ASC can be determined by dividing the spectrum of the mixture by the spectrum of the SAD (as a divisor) followed by subtracting the constant absorbance value of the plateau region, then finally multiplying the obtained spectrum by the spectrum of the divisor. The developed methods have been successfully applied for determination of the studied drugs in different laboratory prepared mixtures and in their pharmaceutical formulation. Statistical comparison between the results obtained by applying the proposed methods and the reported HPLC method was done, and it was found that there was no significant difference between them regarding both accuracy and precision.read more

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Nourudin Wageih Ali, Hala El-sayed Zaazaa, Maha Mohamed Abdelrahman, Maimana Ahmed Magdy and Mohamed Abdelkawy

Guessing Unknown and Disordered Solvent Molecules with SQUEEZE in the Structure Validation Program PLATON

This report describes the assignment of the nature and number of solvent molecules in the refinement of several solvated crystal structures without a prior knowledge of the solvent system used for crystallization for the cases when the solvent molecule cannot be properly modeled. The solvent molecules can be assigned even for twinned crystal structures.read more

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Seik Weng Ng

Thermodynamic and Kinetic Studies of Chromium (VI) Adsorption by Sawdust Activated Carbon

Low cost activated carbon, prepared from saw dust of Ziziphus jujube by chemical activation with phosphoric acid (H3PO4) was characterized and utilized for the removal of Cr (VI) ions from aqueous solutions under different conditions of solution pH, contact time, initial concentration, carbon dose and temperature. Adsorption of Cr (VI) ions was found highly pH dependent that increased with decrease in solution pH. The removal of Cr (VI) ions increased with increase in temperature, initial concentration and contact time until equilibrium was established. Langmuir’s adsorption isotherm model and pseudo - second order kinetic equation were found better fitted to describe the experimental data. Thermodynamic study revealed the feasibility, spontaneity and endothermic nature of the adsorption process. The used carbon was regenerated by treating with HCl solution. In comparison to other adsorbents, the results indicated that the prepared saw dust activated carbon could be an eco-environment friendly and efficient adsorbent for removal of Cr (VI) ions from aqueous solutions.read more

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Mohammad Ilyas, Nadir Khan and Qamar Sultana

Study on the Concentration of Unsaturated Fatty Acid Methyl Esters by Urea Complexation

This study was done to obtain concentrated unsaturated fatty acid methyl esters (FAME) by urea complexation from soybean derived FAME. Effects of urea-to-FAME ratio, 95% ethanol-to-FAME ratio, crystallization temperature and time on the purification of unsaturated FAME were investigated through single factor experiments. Optimum conditions to obtain maximum FAME yield of NUCF with the purity of unsaturated FAME greater than 98% were established using Box-Behnken design (BBD) method and response surface methodology (RSM). Under optimal conditions, the FAME yield was 58.08%, and the purity of unsaturated FAME was 98% at a urea-to-FAME ratio of 1.23, 95% ethanol-to-FAME ratio of 7 and crystallization temperature of 0ºC. Verification results revealed that the predicted values were reasonably close to experimentally observed values of 56.93% and 98.01%.read more

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Bin Jiang, Yan Liu, Luhong Zhang, Yongli Sun, Yuhua Liu and Xuekuan Liu

Purification and Characterization of 29 kDa Acid Phosphatase from Germinating Melon Seeds

Not much progress on the purification and characterization of low molecular weight acid phosphatases from plants has been made as yet. In the current study a low molecular weight acid phosphatase from seedling of melon was purified about 114-fold with specific activity of 45 U/ mg of protein and a recovery of 3 %. The enzyme was found to be homogeneous and showed a single band corresponding to 29 kDa on SDS-polyacrylamide gel electrophoresis. The Km for p-nitrophenyl phosphate was found to be 0.175 mM and Vmax was 42 µmol of substrate hydrolyzed /min/mg of protein at pH 5.5 and at 37° C. The enzyme showed its optimum activity at pH 5.0 and 50o C. The enzyme was thermostable and it retained 70 % activity for 45 min at 60o C. The pH stability was 4.8-6.0. Phosphate, vanadate, molybdate and fluoride acted as strong inhibitors. Metal ions such as Zn+2, Cu+2, Ag+1 and Hg+2 deactivated the enzyme while other divalent ions such as Ca+2 and Mg+2 had no effect.read more

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Umber Zaman, Rubina Naz, Asma Saeed, Mehrin Sherazi and Ahmad Saeed

Thermodynamic Dissociation Constants of Propionic Acid in Water and 1-Propanol Mixtures between 303.15 and 323.15 K

Thermodynamic dissociation constants (Ka) of propionic acid in 0, 5, 10 and 20 wt% 1-propanol-water binary mixtures have been determined between 303.15 and 323.15 K. A conductometric method has been applied to measure the molar conductance of dilute solutions of propionic acid. Fuoss-Kraus conductance equation has been applied to calculate the values of limiting molar conductance (Λ0) and thermodynamic ionization constant (Ka). It was found that both the values of Ka and Λ0 decreased by the increasing of amount of 1-propanol in the binary mixtures. However, Ka values were decreased and Λ0 values were increased by increasing temperatures. The normalized Walden products of the propionic acid have been calculated. Thermodynamic quantities such as change of standard free energy (∆G°), change of standard enthalpy (∆H°) and change of standard entropy (∆S°) have been calculated in case of each of the binary mixtures.read more

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A. K. M. Atique Ullah, Mahmuda Akter and Shakhawat Hossain Firoz

Preparation, Spectroscopic Investigation and Biological Activity of New Mixed Ligand Chelates

Preparation and investigation of new Co(II), Ni(II), Zn(II) and Cr(III) chelates with mixed ligands including Schiff base (L1) formed from the condensation of 4-dimethylaminobenzaldehyde with 2-aminophenol and anthranilic acid (L2) were studied. The obtained Schiff base and mixed ligand chelates were subjected to several physiochemical techniques, in terms of CHN elemental analyses, molar conductivity, magnetic moment measurements, infrared, proton nuclear magnetic resonance, electronic and mass spectra. The analytical data showed the formation of the Schiff base compound and the ratio of metal to ligands of the chelates are 1:1:1[M:L1:L2]. The infrared spectral data exhibited that the used ligands behaving as bidentate ligands towards the metal ions. The proton nuclear magnetic resonance spectral data showed the signals of the active groups in the ligands which entered in chelation with Zn(II) metal ion. The electronic spectral results showed the existence of π→π* (phenyl ring) and n→π*(C=N) of the ligands and suggested the geometrical structures of the chelates. Meanwhile, the mass spectral data revealed the fragmentations of the Schiff base, anthranilic acid and their Ni(II) mixed ligand chelate has been preformed the only chelate conducted for justification. All the prepared mixed chelates were non-electrolyte in nature. The antibacterial activity of the Schiff base, anthranilic acid, metal salts and mixed ligand chelates were studied and found to be that mixed ligand chelates have the most biological activity in comparison to the free ligands and salts.read more

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Faten Suliman Alassbaly, Marei Mailoud El-Ajaily, Salha Faraj Ben-Gweirif and Abdussalam Ali Maihub

Electrochemical Studies of the corrosion inhibition effect of 2-amino-5-ethyl-1,3,4-thiadiazole on low carbon steel in dilute sulphuric acid

The electrochemical behaviour of carbon steel in 0.5 M H2SO4 was studied in the presence of 2-amino-5-ethyl-1 3 4-thiadiazole (TTD) as inhibitor with the aid of weight loss method, potentiodynamic polarization and open circuit potential measurement technique. The effect of inhibitor concentrations, exposure time, corrosion rate and surface coverage on inhibition efficiency was investigated. Results showed that TTD performed excellently in the acid solution with the inhibition efficiency increasing with increase in inhibitor concentration up to a peak value of 80.67% and 90.5% at maximum concentration from weight loss test and potentiodynamic polarization tests. The compound showed cathodic inhibition tendency in solution with the inhibitor molecules been effectively adsorbed onto the steel surface, stifling the electrochemical reactions responsible for corrosion through the exposure hours. Results from statistical analysis through ANOVA software depicts the overwhelming influence of inhibitor concentration on inhibition efficiency compared to exposure time.read more

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Roland Tolulope Loto, Cleophas Akintoye Loto and Patricia Abimbola Popoola