No abstract

Conventional qualitative analysis of ions from inorganic salts and acid-base and redox titrations require relatively large volumes of solution and hence require more reagent and generate relatively large amount of waste. Liquid marbles can be used to cut down the volume of solution and by extension the amount of reagent and volume of waste generated. Liquid marbles were used for qualitative analysis of ions from inorganic salt solutions and acid-base and redox titrations. This was compared with the conventional methods which require milliliters of solution. Fumed silica or fluorinated sericite clay particles of varying degrees of hydrophobicity were used to prepare the marbles. A drop of a test reagent was then placed on the marble, merging with it and initiating a chemical reaction. The characteristic reactions between a salt solution and a test reagent in the marbles were observed provided the reaction was clearly marked by a color change. Concentrations, calculated from the volume at the end-point, compared closely (p ≤ 0.05) with the known ones as well as those calculated from the bulk titration method that requires milliliters of solution. This indicates that the liquid marble method which rather requires microliters of solutions is reliable. These findings are especially important in microfluidics which utilizes microliters of solutions.

Honey foam was prepared using particle (precipitated CaCO 3 ) or molecular (sodium lauryl sulfate) foaming agent. We noted the foam volume and the time it took a foam sample to collapse completely so as to determine the best foaming agent. Foams were prepared by aerating honey in the presence of varying concentrations of the particles or sodium lauryl sulfate. Aqueous foams were similarly prepared for comparison. Sodium lauryl sulfate gave a higher volume of honey foam, which did not collapse completely for more than four months compared with precipitated CaCO 3 particles which gave a smaller foam volume that collapsed completely within four weeks. Aqueous foams prepared from the surfactant, by contrast, collapsed completely within three hours while those prepared from the particles did not collapse within the same timeframe. This shows that the surfactant is a better foaming agent in honey compared with the particles, while the particles are a better foaming agent in water compared with the surfactant.

Mn(II) and Co(II) complexes were prepared by reaction of the metal chlorides with acetylacetone in ammonical aqueous medium. The metal complexes were prepared in order to investigate their antimicrobial activity on some selected pathogens. The characterisation of the complexes was on the basis of various spectroscopic techniques like infrared and ultraviolet studies. The compounds were subjected to antimicrobial activity screening using serial broth dilution method. Minimum Inhibitory Concentration (MIC) and Minimum Bactericidal/Fungicidal Concentration (MBC/MFC) were determined. Mn(II) complex has shown significantly both antibacterial and antifungal activity with a MIC of 1.25 μg/mL while Co(II) complex was noticeable for antifungal activity at the same concentration. Whereas Mn(II) acetylacetonate is a more potent bactericide while Co(II) acetylacetonate is a more potent fungicide, both with MBC/MFC value of 2.5 μg/mL. Antimicrobial agent of the ligand has enhanced on complexation with Mn(II) and Co(II) ions. Though, the potency of the prepared antibiotics on the tested microbes is less compared to the standard drugs (Ciprofloxacin and Fulcin).

Corrosion inhibition characteristics of aspartic acid on  mild steel corrosion in 0.5 M H2SO4 was investigated using weight loss, acidimetry, and electrochemical impedance spectroscopy (EIS). Analysis of the metal surface morphology, uninhibited and inhibited, was carried out through scanned electron microscope. The results showed that the inhibition efficiency increased with increase in inhibitors concentration and rise in temperature for all methods used. The highest v efficiency of  32.36 %, 66.26 % and 80.40 % were obtained for weight loss, acidimetry and EIS, respectively. The low value of efficiency for weight loss compared to other methods should signify the limitation for the method. The increase in efficiency with rise in temperature is a feature of chemical adsorption, which was confoirmed by the value of parameter b of the Adejo-Ekwenchi adsorption isotherm (AEI) model. Values of free energy of adsorption, ?Gads were all negative for all the methods, which means the adsorption processes were spontaneous. The heats of adsorption, Qads values were all positive, implying that the processes were endothermic. Values of activation energy were fairly constant, which is an evident to support the proposed chemical adsorption mechanism. The negative sign in the values of entropy of adsorption, ?Sads is an indication  that the activated complex in the rate-determining step was associative. The data obtained was tested with several isotherms, but found to best fit into the El-Awady, Freundlich and Tempkin adsorption isotherm models.