Ultrafiltration of three laboratory made silica and two commercial silica sols was studied using Amicon YC membrane in a 200 ml capacity batch-cell. The effect of silica particle size, stirring conditions, pressure, pH and silica contents on ultrafiltration was investigated. The results obtained indicate that the smaller particles have, disregarding the stirring conditions, lower filtration flux. The differences observed in filtration flux are more pronounced in the conditions without stirring. The obtained value of the membrane resistance is independent of the conditions investigated (stirring, pressure, pH, silica contents and particle size). The values of the resistance of polarized solids, specific resistance, and the mass of gel per membrane surface unit were calculated for all experimental conditions.
The effect of the addition of varying amounts of acetone, ethanol, ethylene glycol, glycerol and 1,4-dioxane to an aqueous solution on the signal intensities of Ca, Cd, Cu and Fe was investigated by flame atomic absorption spectrometry and inductively coupled plasma atomic emission spectrometry. Correlation between the signal intensity and the main physical characteristics (density, surface tension and viscosity) of these solvents was studied. The influence of the aqueous organic solvent on the signal intensity varied depending on the nature of the aqueous organic solvent and the particular element.
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