VOLUME 35, NO4, AUG-2013
123
 
Optimization of Acid-Activated Bentonites on Bleaching of Cotton Oil

ORAL LACIN, ENES SAYAN, ELIF GULSAH KIRALI

Bentonites are commonly used adsorbent on bleaching cotton oil to produce edible oil products. Bleaching capacities of neutralized cotton oil were investigated with acid-activated Arguvan and Kurşunlu bentonites. Two models for acid activation of the bentonites were developed by using a full factorial experimental design and central composite design. The parameters used to develop these models were contact time, solid to liquid ratio, acid concentration and moisture of bentonite. By using a constrained optimization program, the maximum bleaching capacities of neutralized cotton oil were determined as 99.99% and 48.5% for Arguvan and Kurşunlu, respectively. Optimum results showed that Turkish bentonites (especially Arguvan bentonite) have high bleaching ability and they can be used efficiently to bleach neutralized cotton oil by considering the favorable volume weight, capacity of oil adsorbed and filtration rate
Pages(1053)
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Simultaneous Determination of Six Food Additives i

QINGHUA YAN, LI YANG, XIAOQIN MA, HUIGEN FENG

A reversed-phase high performance liquid chromatographic method for the successful separation and determination of 6 synthetic food additives (aspartame, acesulfame potassium, benzoic acid, sodium saccharin, tartrazine and sunset yellow) was developed. A EclipseXDB-C18 column (250×4.6 mm I.D.; 5 µm) was used and the mobile phase contained methanol and 0.02 mol/L ammonium acetate (pH 6.0) (30:70, v/v) was pumped at a flow rate of 0.7 mL/min at room temperature. Successful separation conditions were obtained for all the compounds using an optimized gradient elution within 10 min. The diode array detector was used to monitor the food additives at 230 nm. The method was thoroughly validated, detection limits for all substances varied between 0.03 and 1.35 µg/mg, the intra-day precision (as RSD) ranged from 1.57% to 4.72 %, the inter-day precision (as RSD) was between 2.05 % and 4.18 %. Satisfactory recoveries, ranging from 90.00 % to 109.87 %, were obtained. The proposed system was applied to drink samples
Pages(1060)
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Density, Electrical Conductivity, Acidity, Viscosity and Raman Spectra of Aqueous NaBO2, Na2B4O7 and NaB5O8 Solutions at 298.15 and 323.15K

ZHOU YONGQUAN, FANG CHUNHUI, FANG YAN, ZHU FAYAN

Density, electrical conductivity, viscosity and acidity of aqueous NaBO2, Na2B4O7 and NaB5O8 solutions were preciously measured as functions of concentration from dilute to super-saturation at 298.15 and 323.15 K. The results are in reasonable agreement with literature data where comparisons are possible. Semi-empirical equations for those properties vs concentration were also suggested. Coupling with Raman spectra of some concentrated samples, main species and possible equilibria were listed by elaborate deduction. In aqueous sodium borate solutions, at least five polyborate species i.e. B(OH)3, B(OH)4-, B3O3(OH)4-, B4O5(OH)42- and B5O6(OH)4- exist, and their distribution and relevant mechanism were also suggested
Pages(1066)
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Novel QSAR Combination Forecast Model for Insect Repellent Coupling Support Vector Regression and K-Nearest-Neighbor

LI FENG WANG, XIAN SHENG TAN, ZHE MING YUAN, LIAN-YANG BAI

To improve the precision of quantitative structure-activity relationship (QSAR) modeling for aromatic carboxylic acid derivatives insect repellent, a novel nonlinear combination forecast model was proposed integrating support vector regression (SVR) and K-nearest neighbor (KNN): Firstly, search optimal kernel function and nonlinearly select molecular descriptors by the rule of minimum MSE value using SVR. Secondly, illuminate the effects of all descriptors on biological activity by “multi-round enforcement resistance-selection”. Thirdly, construct the sub-models with predicted values of different KNN. Then, get the optimal kernel and corresponding retained sub-models through subtle selection. Finally, make prediction with leave-one-out (LOO) method in the basis of reserved sub-models. Compared with previous widely used models, our work shows significant improvement in modeling performance, which demonstrates the superiority of the present combination forecast model
Pages(1075)
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Study on the Way of Urea Removal by BAF

YAN LILONG, LI WEIGUANG, REN YUAN, LIU YU, ZHANG YING

Biofilm process is a kind of efficient way for sewage with high concentration of urea. A lot of researches on removal efficiency were carried out, but there existed less research for the process of urea removal. To understand the way of urea removal by biofilm process, biological aerated filter (BAF) was used to deal with sewage with high concentration of urea from a chemical plant, by studying adsorption property of the carrier, biomass and biological activity on the carrier, and contrastive analysis between hydrolysis product of urea and theoretical value was carried out and the microbial flora of urea removal was preliminarily determined using the method of inhibiting biological activity. The results showed that, removal of urea by BAF was mainly the result of biological action, the adsorption capacity of activated carbon for urea was limited, the dominant bacterial communities for the hydrolysis of urea were heterotrophic bacteria, and parts of nitrosobacteria and nitrobacteria also had a certain capacity of hydrolyzing urea
Pages(1081)
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Study of Co (II) and Cr (VI) Adsorption from Aqueous Solution by CaCO3

FRANCISCO GRANADOS CORREA, ELIZABETH GARCÍA ALCÁNTARA, JAIME JIMÉNEZ-BECERRIL

Calcium carbonate was synthesized, characterized, and utilized in water purification. The adsorption of Co(II) and Cr(VI) ions from aqueous solutions in CaCO3 was studied as a function of different optimal conditions, such as contact time, initial metal ion concentration and temperature, at fixed solid/solution rations by using batch adsorption experiments. Characterization studies confirmed that synthesized CaCO3 is crystalline with a high phase purity and specific surface area of 9.68 m2/g. The kinetic processes of the systems were described in order to provide a more clear interpretation of the rate of adsorption mechanism. Langmuir, Freundlich and Dubinin-Radushkevich isotherms were used as the model adsorption equilibrium data. The maximum amounts (qmax) of Co(II) and Cr(VI) adsorbed in CaCO3 were 2.29 and 1.06 x 10-2 mg/g, respectively. The pseudo-second order kinetic model was found to better fit the experimental data measured for both metallic ions. The adsorption processes of both systems were adjusted by the Freundlich isotherm. The adsorption energies calculated from Dubinin-Radushkevich isotherm show that the adsorption processes were physical in nature. Based on the thermodynamic data of ΔH°, ΔS° and ΔG obtained, it can be concluded that the processes of Co(II) and Cr(VI) ion adsorption in CaCO3, were endothermic, spontaneous, and are the result of physical adsorption process. These features make the CaCO3 a potential adsorbent for both Co(II) and Cr(VI) adsorption from wastewater
Pages(1088)
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Application of l-Ascorbic Acid and its Derivatives (Sodium Ascorbyl Phosphate and Magnesium Ascorbyl Phosphate) in Topical Cosmetic Formulations: Stability Studies

SLIM SMAOUI, HAJER BEN HLIMA, ADEL KADRI

The present study aimed to formulate and subsequently evaluate a topical skin-care cream (o/w emulsion) from l-ascorbic acid and its derivatives (sodium ascorbyl phosphate and magnesium ascorbyl phosphate) at 2% versus its vehicle (Control). Formulations were developed by entrapping it in the oily phase of o/w emulsion and were stored at 8°C, 25°C and 40°C (in incubator) for a period of four weeks to investigate their stability. In the physical analysis, the evaluation parameters consisted of color, smell, phase separation, centrifugation, and liquefaction. Chemical stability of both derivatives was established by HPLC analysis. In the chemical analysis, the formulation with sodium ascorbyl phosphate was more stable than those with magnesium ascorbyl phosphate and l-ascorbic acid. The microbiological stability of the formulations was also evaluated. The findings indicated that the formulations with l-ascorbic acid and its derivatives were efficient against the proliferation of various spoilage microorganisms, including aerobic plate counts as well as Pseudomonas aeruginosa, Staphylococcus aureus, and yeast and mold counts. The results presented in this work showed good stability throughout the experimental period. Newly formulated emulsion proved to exhibit a number of promising properties and attributes that might open new opportunities for the construction of more efficient, safe, and cost-effective skin-care, cosmetic, and pharmaceutical products
Pages(1096)
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Optimization of the Extraction of Flavonoids from Grape Leaves by Response Surface Methodology

KORBANJHON BRAD, YAN ZHANG, WEI LIU

The extraction of flavonoids from grape leaves was optimized to maximize flavonoids yield in this study. A central composite design of response surface methodology involving extracting time, power, liquid-solid ratio, and concentration was used, and second-order model for Y was employed to generate the response surfaces. The optimum condition for flavonoids yield was determined as follows: extracting time 24.95 min, power 72.05, ethanol concentration 63.35%, liquid-solid ratio 10.04. Under the optimum condition, the flavonoids yield was 76.84 %.
Pages(1103)
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A Sensor for Determination of Tramadol in Pharmaceutical Preparations and Biological Fluids Based on Multi-Walled Carbon Nanotubes-Modified Glassy Carbon Electrode

MOHAMMAD AFRASIABI, ZEINAB REZAYATI ZAD, SHOKAT KIANIPOUR, ALI BABAEI, ALI REZA TAHERI

A chemically modified electrode is constructed based on multi-walled carbon nanotube modified glassy carbon electrode (MWCNTs/GCE). It is demonstrated that this sensor could be used for determination of pharmaceutical important compound tramadol (TRA). The measurements were carried out using differential pulse voltammetry (DPV), cyclic voltammetry (CV) and chronoamperometry (CA) methods. DPV experiments of various concentration of TRA showed two linear dynamic ranges. The first linear dynamic range was from 4 μM to 35 μM, and the second linear dynamic range was between 60 μM to 550 μM. A detection limit of 0.38 µM (S/N = 3) was obtained. The analytical performance of this sensor has been evaluated for the detection of TRA in human serum, human urine and some pharmaceutical preparations with satisfactory results
Pages(1106)
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Application of Multi-Walled Carbon Nanotubes Modified Glassy Carbon Electrode for Determination of Mefenamic Acid in Pharmaceutical Preparations and Biological Fluids

MOHAMMAD AFRASIABI, SHOKAT KIANIPOUR , ZEINAB REZAYATI ZAD, ALI BABAEI

A chemically modified electrode is constructed based on multi-walled carbon nanotube modified glassy carbon electrode (MWCNTs/GCE). It is demonstrated that this sensor could be used for determination of pharmaceutically important compound mefenamic acid (MEF). Differential pulse voltammetry (DPV) experiments of various concentration of MEF showed two linear dynamic ranges. The first linear dynamic range was from 2 μM to 40 μM, and the second linear dynamic range was between 50 μM to 360 μM. A detection limit of 0.21 µM (S/N = 3) was obtained. Under optimal conditions the modified electrode exhibited high sensitivity and stability for determination of MEF, making it a suitable sensor for the submicromolar detection of MEF in solutions. The analytical performance of this sensor has been evaluated for the detection of MEF in human serum, human urine and a pharmaceutical preparation with satisfactory results
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