Studies with Model Membrane: The Effect of Temperature on Membrane Potential

Membrane potentials for silver bromide parchment supported membrane at different temperatures (30 – 70oC) have been measured. Experimental results were analyzed on the basis of the Kobatake equation, and some characteristic parameters (α, β, and mobility ratios) have been evaluated. The mobility ratios of ions in the membrane phase (u+/u-) are found to be increased with temperature. This order may apparently lead to the conclusion that the ion size is the controlling factor and the membrane is cation exchanger. The activation energy was also obtained. The activation thermodynamics parameters, enthalpy of activation ΔH‡, entropy of activation ΔS‡ and free energy of activation ΔG‡ have been estimate

Complexation of 1,4-bis (3-(2-pyridyl) pyrazol-1-ylmethyl) benzene (1,4-PPB) with Cu (II), Co (II), and Ni (II):: Spectrophotometric Studies in Mixed Solvent (EtOH-H2O)

The stability and composition of the complexes of 1,4-bis (3-(2-pyridyl) pyrazol-1-ylmethyl) benzene (1,4-PPB) with Cu (II), Co (II), Ni (II): have been investigated using spectrophotometric method in mixed (1:1) solvent of ethanol and water. Various experimental parameters, which include pH, ionic strength, solvent composition, and time, have been studied. The stoichiometry and formation constant of each complex have been evaluated using Job's method. Spectrophotometric results show the formation of 1:1 complexes with stability order of Co > Ni > Cu. Molar absorptivity values of the complexes have also been determined

Determination of major and minor elements in dairy products produced in Misurata city – Libya

Concentrations of minor metals (cadmium Cd, lead Pb, copper Cu, Zinc Zn, and chromium Cr) and major nutritional elements (sodium Na, and potassium K) were analyzed in some dairy products (15) produced by four local companies in Misurata-Libya. Minor elements were determined using Atomic Absorption Spectrometer and major elements (Na and K) using Flame Emission Photometer. For heavy metals, the average levels of zinc was the highest, followed by levels of lead, cadmium, and chromium, and finally the levels of copper was the lowest. For major elements, the levels of potassium were higher than sodium in all tested samples. Generally, Heavy metal concentrations varied significantly depending upon the type of the product and significant differences were observed in the mean values of heavy metals in different types of dairy products. However, the levels of heavy metals in fresh milk were lower than the levels in other products (butter milk, yoghurt, and yoghurt drink). Finally, further investigations are needed to identify the cause of elevated heavy metal levels especially in dairy products

Biosorption Study of Zn(Ii), Cu(Ii), Pb(Ii) And Cd(Ii) Ions by Palm Leaves Activated Carbon

The aim of the present study is to investigate the efficiency of palm leaves activated carbon on the removal of lead (Pb), zinc (Zn), copper (Cu), and cadmium (Cd) from the aqueous solution. The effect of various process parameters such as pH (2 – 10), initial metal ion concentration (50 – 1000 mg/L), particle size (125, 500, 800 μm), and temperature (303, 313, 323 K) was studied using batch adsorption technique. Thermodynamic parameters were also evaluated. The maximum metal ion removal efficiency of 94.5, 94.1, 87.4, and 90.7% for Pb, Cd, Zn, and Cu, respectively, was reached at an optimum pH of 5, biosorbent dosage of 1.0 g, and initial metal ion concentration of 50 ppm. The Freundlich adsorption isotherm model best described the removal of metal ions on palm leaves activated carbon with high correlation coefficients (0.98 – 1.00). The adsorption process was found to be favorable since the intensity of adsorption, n lies within 1 to 10. The adsorption capacity values were 40.0, 38.3, 38.0, and 40.00 mg/g for lead (Pb), zinc (Zn), copper (Cu), and cadmium (Cd), respectively. The metal ion adsorption was also found to be endothermic in nature. The efficiency was increased with an increase in temperature implying the process should be performed at a controlled temperatur

Spectrophotometric Complex formation Study of Murexide with Nickel and Cobalt in Aqueous Solution

In the present study, the formation constant and the stoichiometry of murexide complexes with Co (II) and Ni (II) have been determined spectrophotometrically in aqueous solution at 25oC. Two experimental parameters governed the complex formation, pH and time, have been investigated. The formation and stoichiometry constants have been determined by two methods: Job's and mole ratio's methods. The absorption maxima for Co-murexide and Ni-murexide complexes were: 480, 460 nm, respectively. The two Spectrophotometric methods confirm the formation of 2:1 (M:L) complexes with stability arrange of: Co > Ni. The formation constants (Kf) determined by the Job's method were as follows: 2.06x1014 and 1.21x1011 for Co-murexide and Ni-murexide, respectively. Also, using mole ratio's method, the formation constants were found to be:  9.18x1011 and 6.01x1011. Molar absorptivity values of the studied complexes have also been determined (by Job's and mole ratio's methods) and the average values were: 18235 and 13284 l/mol.cm for Co and Ni, respectively

Phytochemical Screening, Antioxidant Capacity Measurement, and Mineral Content Determination of Thymus vulgaris L. Extracts

The aim of this study was to evaluate the chemical composition and antioxidant activity of Thymus vulgaris L. extracts. T. vulgaris L. is a medicinal plant that has various bioactive compounds. Four different solvents (ethanol, water, ethyl acetate, and chloroform) were used to extract these compounds from the plant. The phytochemical screening of the extracts showed that the ethanolic extract had the highest diversity of compounds, including coumarins, flavonoids, alkaloids, tannins, phenols, carbohydrates, and proteins. The total phenolic and total antioxidant contents of the ethanolic extract were measured by the Folin–Ciocalteu and phosphomolybdenum methods, respectively. The ethanolic extract had a high phenolic content of 77.7 mg gallic acid equivalent/g dry weight, which indicates its potential antioxidant capacity. The mineral content of T. vulgaris L. was also assessed by flame photometry and atomic absorption spectrophotometry after dry digestion. The plant contained five macroelements (K, Na, Ca, Mg, P) and three microelements (Fe, Cu, Zn) in different concentrations. The highest concentration was found for potassium (15259 mg/kg), followed by calcium (5118 mg/kg) and sodium (4793 mg/kg). The lowest concentration was found for phosphorus (1400 mg/kg), which was still higher than the microelements. Among the microelements, zinc had the highest concentration (24.82 mg/kg), followed by iron (17.44 mg/kg) and copper (14.98 mg/kg). The results of this study provide useful information for the users, collectors and practitioners of medicinal plants from polluted areas, as they can evaluate the quality and safety of T. vulgaris L. for human consumption

Physicochemical properties and nutritional values of pasteurized milk and long-life milk: A comparative study

In this paper, physicochemical and nutrition values (moisture, ash, nonfat solids, total solids, protein, fat, lactic acid, pH, and total sugar contents) in several pasteurized milk and long-life milk samples (11) sold in Misurata city-Libyan supermarkets have been evaluated. Several techniques have been used for these determinations. Generally, the concentrations of these parameters were varied significantly depending upon the type of the milk type. The levels of proteins, fats, total acidity, and total sugars were as follows: 2.43 – 3.50 %, 0.25 – 3.50 %, 0.13 – 0.18 %, and 2.96 – 4.39 %, respectively. However, the levels of the investigated parameters were in the acceptable range reported by the Libyan standard specifications. Also, our results were similar to those reported by several researchers. Finally, further investigations should be carried out to monitor the quality of a greater number of milk samples from various companies in Libya and to confirm their quality