Dimitre Karamanev

RAPID SIMULTANEOUS QUANTITATIVE DETERMINATION OF FERRIC AND FERROUS IONS IN DRAINAGE WATERS AND SIMILAR SOLUTIONS

Abstract A rapid, precise method for simultaneous measurement of ferrous and ferric iron concentrations in drainage and other waters is reported. The determination of both ferric and total iron concentrations are made in the same solution at different light wavelengths, which significantly reduces the error of the analytical procedure. The method is based on the colorimetric measurement of red-colored ferric–sulfosalicylate complex formed at low pH. After the addition of ammonia which leads to the increase in pH, the 5-sulfosalicylic acid (SSA) forms a yellow complex with all the iron ions in solution. The wavelengths of maximal light absorbance for both these complexes were determined. They were 500 and 425 nm, respectively. The relationship between both the ferric and total iron concentrations and the light absorbance obeys Beers law under the conditions studied. The optimal ratio and volumes of the reagents used were determined. The effect of the ions usually found in mine drainage waters along with iron ions was studied. The cultivation media for the iron-oxidizing bacteria Thiobacillus ferrooxidans and the bacterial mass itself were found to have no effect on the iron determination. It was found that the color complexes were stable for a long time (at least 48 h).

Hydrodynamic characteristics of free rise of light solid particles and gas bubbles in non-Newtonian liquids

Abstract The main objective of this study was to determine the primary parameters affecting the rise of gas bubbles and light solid particles in non-Newtonian (pseudoplastic) liquids. The results obtained for the rise of light solid particles were used to explain the behavior of rising gas bubbles. These results were also compared to that of free-falling heavy particles. The main parameters studied were the drag coefficient, trajectory of rise, and terminal velocity as a function of the shape and volume of gas bubbles and solid particles, and the rheological properties of the non-Newtonian (pseudoplastic) liquid. It was determined that the most effective method for doing this was with a movable video camera unit. It was discovered that freely rising light solid particles have similar behavior to gas bubbles for a wide range of Reynolds numbers. This indicated that the hydrodynamics of freely rising light particles could be used to describe the behavior of gas bubbles. The comparison of the behavior of light solid particles and gas bubbles allowed us to determine the effect of the internal circulation of a gas bubble on the hydrodynamics of its rise. A new correlation was proposed to predict the drag coefficient and terminal velocity of gas bubbles in non-Newtonian (pseudoplastic) solutions.