Applied Chemistry

Metal- ligand complexation in solutions was studied in water-methanol media by pH-metric titration with the standard glass electrode at ionic strength of 0.1M KNO_3. The titrations were carried out at various temperatures 35^oC, 45^oC, and 55^oC and the pKa values (stability constants) were determined. Copper (II) with benzimidazole gave pKa’s of 2.86, 2.52, and 2.46; Stability constant (logK) 338.80, 331.13 and 288.40 while Nickel (II) benzimidazole gave pKa’s 2.51, 2.60 and 2.38 and Stability constant (logK) 323.59, 398.11 and 239.85 respectively.  It was revealed that the stability constants of the metal complexes decreased as the temperature increases. Formation constants obtained for these complexes showed that metal- ligand ratio were in the range of 1:1 and 1:2. The thermodynamic parameters were also determined at the working temperatures and the results obtained showed negative ?H and Gibb’s free energy (?G) indicating exothermic and spontaneous reactions.

A simple, reliable and selective square wave cathodic Adsorptive stripping (SWCAS) voltammetric method at modified carbon paste electrode (CPE) for determination of Cobalt(II) has been developed and evaluated. Square wave Cathodic Adsorptive Stripping Voltammetric (SWCASV) mechanism is proposed to interpret the amplified sensitivity. The procedure is based on the interfacial preconcentration of Cobalt (II) ion on magneson through a surface coordination effect. Different parameters such as medium, pH, accumulation potential, scan rate, accumulation time and ionic strength were tested to optimize the conditions for the determination of Cobalt(II) ion. The adsorbed form is reduced irreversible at optimal conditions viz; 0.15M Britton–Robinson universal buffer (pH~9.5). Linear concentration range 2×10-12 - 6×10-11 M (0.00012 – 0.00354 ng/mL (at 60s, can be determined successfully. The interferences of some common interfering species and some metal ions were studied. The application of the procedure in Lab tap water sample demonstrates that it is possible to determine Co(II) ion at a level as low as 5.13×10-10 mol/L (0.03 ng/mL) in real sample with a recovery of 103%, a standard deviation (triplicate measurements) of 3.08%, and a confidence level of 95%. The concentration of Co(II) in lab tap water sample was confirmed by analysis the sample by using Inductively Coupled Plasma Emission Spectrometer.

A simple and reliable square wave anodic stripping (SWAS) voltammetric method at carbon paste electrode (CPE) of Mebeverin hydrochloride (MEB) in pharmaceutical dosage forms (tablet) and in biological fluids (spiked and real urine samples) has been developed and evaluated. Different parameters such as medium, supporting electrolyte, pH, accumulation potential, scan rate and accumulation time, were tested to optimize the conditions for the determination of MEB. The adsorbed form is oxidized irreversibly under optimal conditions, viz., 0.1 M Phosphate buffer (pH~8), 0.1M KCl, a linear concentration ranges from 0.233 to 42.406 µg/mL of MEB, at accumulation times 60, 150 s, can be determined successfully. The standard addition method was used to determine the MEB in pure solutions, tablets and in biological fluids with satisfactory results. The data obtained are compared with the standard official method.

The Schiff base chelate of Cu(II) and Ni(II) derived from condensation reaction of salicylaldehyde and 2-aminophenol have been synthesized and investigated by different physicochemical techniques. The resulting complexes were characterized by elemental analysis, molar conductance, FT-IR, melting point or decomposition measurements, solubility in different solvent. The elemental analysis data show the formation of 1:1 metal to ligand ration. The Schiff base act as a tridentate ligand, coordinated through daprotonated phenolic oxygen and azomethine Nitrogen atom. The synthesized chelates were assayed for antibacterial activity against some pathogenic bacteria:Staphylococcus aureus, and Escherichia coli, and the fungi: Aspergillums niger and Candida albican, using dics diffusion method. The synthesized Schiff base complexes exhibit higher antimicrobial activity than the free Schiff base due to the chelation.

The spectroscopic characteristics (IR) and the thermal properties (TGA, DTG and DTA) of the solid complexes obtained by the reaction of 2-hydroxyphenylhydrazoacetoacetanilide (2-HPHAAA) with Uranyl(II), and Thorium (IV) are reported and discussed.

A Lamotrigine (LMG) reagent, 6-(2,3-dichlorophenyl)-1, 2,4-triazine-3,5-diamine. Its molecular formula and molecular weight are C9H7N5Cl2 and 256.09 respectively, was employed for the sensitive spectrophotometric determination of gold(III). The gold(III) ion forms a yellow-coloured complex with LMG in an aqueous solution at pH 3.0. The gold complex shows the absorption maximum at 400 nm, and Beer, s law obeyed in the range of 10-160 µg/ml. The molar absorptivity and sandell, s sensitivity were found to be 1.38 X 103 mol -1 cm-1 and 0.0184 µg cm-2 respectively. The complex shows 1:1 [Au(III) : LMG] stochiometry with a stability constant of 4.77X104. The interference effect of various diverse ions has been studied. In addition to zero- order, first derivative spectrophotometric methods was also developed for the determination of gold(III) in trace amount which was more sensitive than the zero-order method. The developed method has been used for the determination of gold(III) in various kinds of alloys. The results was in excellent agreement with certified values.

Detergents includes some surfactants like LAS (linear alkyl sulphonate), TPBS (Tetra Propylene derived alkyl Benzene Sulphonate), ABS (branched chain alkyl benzene sulphonate) etc. LAS is most widely used anionic detergents and it have biodegradable capacity, while ABS like surfactants are resistant to biodegradability. The present study specially aims to study spectrophotometerically the contamination level of water of river Gomti by the presence of anionic detergents flowing from the heart of Jaunpur city. In the river Gomti direct wastes like municipal garbage, sewage as well as industrial wastes is dumped without treatment. River Gomti is continuously been contaminated by the sewage and other types of wastes. This study revealed that there is gradual increase in the level of anionic detergents as we proceed from January to December along the years of study 2009, 2010 and 2011.

The voltammetry methods have revealed in the water of the Cotonou channel, the presence of organic and inorganic complexes of metals, such as: Zn-Carbonate, Zn2+, ZnSO4, Zn-OM, Cu-Carbonate, Cu2+, Cu(OH)2, Cu-OM, Pb-Carbonate, Pb2 +, Pb-OM, Cd-Carbonate, Cd2+, and Cd-OM. Their concentrations were variable with the water pH and depended on the season. At pH values ranging 6.5 - 7.2, metals were complexed by carbonate ions present in the water. Zinc is predominantly present as Zn2+ in the rainy season and Cu2+ levels were decreasing when pH was increasing. 80% of the total lead appeared to be complexed as Organic matter complex lead (Pb-OM), and cadmium (Cd-OM) which, unlike other metals, was mainly present in free Cd2+ form.

Activated carbon was prepared from Sterculia quadrifida seed shell waste by Phosphoric acid activation. The adsorption of Acid Blue 92 and Direct Red 28 on this Phosphoric acid treated activated carbon was investigated to assess the possible use of this adsorbent for the processing of dyeing industry wastewater. The influence of various factors such as initial dye concentration, temperature and Particle size on the adsorption capacity has been studied. Kinetic data have been studied using Pseudo-first order, Elovich model and Pseudo-second order equations for understanding the reaction mechanism.

Physico-chemical properties of ink particles have an important role in deinking using either washing or flotation processes. To study such properties, turbidity, zeta potential and surface tension techniques were used in this research. In this work, oleic acid and xylanase are used as surface modifiers for the ink particles. The results show that addition of enzyme alone to the ink suspension and due to its adsorption on ink particles, increase ink dispersion. This will facilitate separation of ink using washing process. On the other hand, the addition of enzyme-oleic acid blend to ink suspension reduces the electronegativity of ink particles. This will make the ink particles to flocculate and facilitate its adhesion to the negatively charged air bubbles during the flotation process. It is expected that this fundamental knowledge will lead to process technology improvements in the deinking of office wastepaper.