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1

Monitoring of contamination of coal processing plants and environmental waters using bubble velocity measurements – advantages and limitations

Zawala J., Malysa E., Krzan M., Malysa K.

Physicochemical Problems of Mineral Processing

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2014

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Vol. 50, iss. 1

143--157

EN

The paper presents fundamentals of a simple physicochemical method (SPMD) and analysis of results obtained when the method was applied for detection of organic contaminations (surface-active substances SAS) in samples of environmental and industrial waters. The method is based on measurements of variations of air bubble local velocities, which can be significantly changed in presence of surface-active contaminants. Lowering of the bubble velocity is a consequence of a motion induced dynamic adsorption layer (DAL) formed over surface of the rising bubble. The DAL formation retards the surface fluidity and the bubble rising velocity can be lowered by over 50% when the bubble surface is completely immobilized. We showed that the SPMD is a very sensitive tool (detection limit even below 1 ppm) for detection of various kinds of surface-active substances (ionic, non-ionic) in water samples. On the basis of results obtained using precise laboratory set-up, an accuracy of the SPMD is discussed. Moreover, effect of inert electrolyte addition on the bubble velocity lowering and value of detection limit of the SPMD is discussed. Simple approach, enabling quantitative analysis of the surface-active contaminants in samples collected, based on “equivalent concentrations” determination, is proposed. Results obtained for industrial (Jankowice and Knurow coal processing plants, Jaslo Refinery channel) and environmental waters (Wisloka and Ropa river) are used for detailed analysis and critical discussion of advantages and limitations of the SPMD.

2

Influence of electrolyte presence on bubble motion in solutions of sodium n-alkylsulfates (C8, C10, C12)

Krzan M., Malysa K.

Physicochemical Problems of Mineral Processing

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2012

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Vol. 48, iss. 1

49-62

EN

Influence of sodium chloride (NaCl) addition on bubble velocity in solutions of sodium n-octylsulfate (SOS), n-decylsulfate (SDS) and n-dodecylsulfate (SDDS) was studied. The NaCl concentration was varied from 0.0001 to 0.05 M. Profiles of the bubble local velocity, that is, variations of the bubble local velocity with distance from the point of the bubble formation (capillary), were determined. At low sodium n-alkylsulfates concentrations the bubbles, after the acceleration stage, reached a maximum velocity followed by a deceleration stage tending to attain their terminal velocity. The maximum disappeared at high SOS, SDS and SDDS concentrations. Electrolyte alone did not affect the bubble velocity. However, addition of even small amounts of NaCl into solutions of sodium n-alkylsulfates affected the bubble motion. The effect was especially significant at low concentrations of the surfactants studied, where the bubble terminal velocity was lowered from ca. 30-34 cm/s (no electrolyte) down to ca. 15 cm/s in 0.01M NaCl presence. The electrolyte affected the bubble motion via its influence on state of the Dynamic Adsorption Layer formed over surface of the bubbles rising in sodium n-alkylsulfates solutions.

3

When and how α-terpineol and n-octanol can inhibit the bubble attachment to hydrophobic surfaces

Kosior D., Zawala J., Malysa K.

Physicochemical Problems of Mineral Processing

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2011

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Vol. 47

169-182

EN

Kinetics of the three phase contact (TPC) formation and phenomena occurring during collision of the rising bubble with Teflon plates of different surface roughness were studied in distilled water, α-terpineol and n-octanol solutions, using a high-speed camera of frequency 1040 Hz. Influence of solution concentration and surface roughness on time of the TPC formation and the time of drainage of the film formed between the colliding bubble and Teflon surface was determined. The surface roughness of the Teflon plates was varied within range 1- 100 µm. It was found that at small α-terpineol and n-octanol concentrations the time of the TPC formation was shortened in respect to distilled water. However, at their high concentrations the time of TPC formation was again longer and magnitude of this effect depended on the surface roughness. For example for Teflon surface of roughness 40-60 µm the time of TPC formation was even 20-30 ms longer. The data obtained indicate that this effect is related to presence of air at the hydrophobic solid surfaces. The mechanism of this prolongation of the time of TPC formation due to the frother overdosage is proposed.

PL

Badano kinetykę powstawania kontaktu trójfazowego podczas kolizji pęcherzyka w wodzie i w roztworach α-terpineolu i n-oktanolu z płytkami Teflonowymi o różnej szorstkości powierzchniowej, przy użyciu szybkiej kamery o częstotliwości 1040Hz. Określono wpływ stężenia substancji powierzchniowo aktywnych i szorstkości powierzchniowej na czas powstawania kontaktu trójfazowego i czas wyciekania cienkiego filmu ciekłego powstającego pomiędzy pęcherzykiem i powierzchnią Teflonu. Szorstkość powierzchniowa Teflonu była modyfikowana w zakresie 1-100 µm. Wykazano, że w roztworach o małych stężeniach α-terpineolu i n-oktanolu czas powstawania kontaktu trójfazowego uległ skróceniu w porównaniu do wartości zmierzonych w czystej wodzie. Jednakże, przy wysokich stężeniach badanych spieniaczy następowało znowu wydłużenie czasu powstawania kontaktu trójfazowego, a wielkość tego efektu była uzależniona od szorstkości powierzchni płytki teflonowej. Przykładowo dla płytki teflonowej o szorstkości powierzchniowej 40-60 µm czas powstawania kontaktu trójfazowego uległ wydłużeniu nawet o 20-30 ms. Wyniki uzyskane wskazują, że efekt ten jest związany z obecnością powietrza na hydrofobowej powierzchni ciała stałego. W pracy przedstawiono mechanizm wydłużenia czasu powstawania kontaktu trójfazowego przy nadmiernej dawce spieniacza.

4

Influence of adsorption of n-alkyltrimethylammonium bromides (C8, C12, C16) and bubble motion on kinetics of bubble attachment to mica surface

Niecikowska A., Zawala J., Malysa K.

Physicochemical Problems of Mineral Processing

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2011

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Vol. 47

237-248

EN

Influence of adsorption of n-alkyltrimethylammonium bromides (C8, C12, C16) and formation of motion induced dynamic architecture of adsorption layer (DAL) over surface of the colliding bubble on kinetics of three-phase contact (TPC) formation at mica surface was studied. The dynamic phenomena occurring during the bubble collisions were monitored using a high-speed camera of frequency 1040 Hz. The effect of solution concentration and the DAL formation, due to the bubble motion, was determined. It was showed that stability of the wetting film formed between the colliding bubble and mica surface was governed by the electrostatic interactions between the film interfaces. It was found that when the distance covered by the bubble (i.e. the distance between the capillary and the mica surface) was L=3 mm (location "close") then the time of the three phase contact formation (tTPC), was significantly shorter than for the L=100 mm (location "far"). The differences between the tTPC for the locations "close" and "far" were the largest at lowest concentration. The mechanism responsible for significant differences in the tTPC values for the location "close" and "far" is described.

PL

Badano wpływ adsorpcji n-alkilotrimetyloamoniowych bromków (C8, C12, C16) oraz utworzenia na powierzchni pęcherzyka, ruchem indukowanej dynamicznej architektury warstwy adsorpcyjnej (DAL), na kinetykę powstawania kontaktu trójfazowego (TPC) na powierzchni miki. Zjawiska zachodzące podczas kolizji pęcherzyka były rejestrowane przy użyciu szybkiej kamery o częstotliwości 1040 Hz. Określono wpływ stężenia roztworów i utworzenia DAL na kinetykę powstawania TPC. Wykazano, że stabilność ciekłego filmu, powstającego w trakcie kolizji pomiędzy pęcherzykiem a powierzchnią miki, jest determinowana przez siły elektrostatyczne pomiędzy granicami faz, które tworzą ciekły film. Kiedy pęcherzyk pokonywał odległość (od kapilary do powierzchni miki) L=3 mm (lokalizacja "blisko") czas powstawania kontaktu trójfazowego był znacznie krótszy, w porównaniu z odległością L=100 mm ("daleko"). Różnice obserwowane dla L=3 mm i L=100 mm wzrastały wraz ze zmniejszeniem stężenia. Przedstawiono mechanizm wyjaśniający znaczące różnice w czasie powstawania kontaktu trójfazowego dla położenia "blisko" i "daleko"

5

Influence of Teflon Surface Roughness on the Contact Angle and the Bubble Attachment in Water

Terpilowski K., Krasowska M., Chibowski E., Malysa K.

Polish Journal of Chemistry

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2008

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Vol. 82, nr 1-2

11-16

EN

In this study the advancing and receding contact angles of waterweremeasured on Teflon plates. Dynamic phenomena occurring during the bubble collision, attachment and the three phase contact formation (TPC) at the Teflon plates of different surface roughness were monitored, using a high speed camera SpeedCam (1182 Hz). Variations of the receding contact angles and the diameters of bubble attachment perimeters to Teflon were found to correlate to some extent.