Detachment Force Of Air Bubble Research Articles

Detachment Force of Air Bubbles Detached from Low-Rank Coal Surface in the Presence of Adsorbed Oleic Acid-Dodecane Collector Mixture.

It is well known that mixed collectors can effectively strengthen the flotation of low-rank coal. However, less concern has been paid to the detachment of low-rank coal flotation using mixed collectors. In this study, the force of air bubble detachment from low-rank coal surface treated by oleic acid (OA), dodecane (D), and oleic acid–dodecane (OA–D) collector mixture was investigated using microforce balance. The results showed that the process of bubble detachment from the low-rank coal surface was divided into three stages: relaxation stage, stretching stage, and sliding stage. The equilibrium contact angle and critical contact angle were the transition points between different stages. The order of detachment force required for bubble detachment from the surface of low-rank coal was OA–D > OA > D, indicating a synergistic effect between OA and D. Based on the three parameters of equilibrium contact angle, critical contact angle, and contact line length, a theoretical model was proposed to calculate the detachment force. The calculated results were in agreement with the measured results.

The influence of oxidation degree of galena surface and of ethyl xanthate on the stability of galena-air aggregates

Measurements of the detachment force of air bubble from galena surface in water and in potassium ethyl xanthate solution at natural pH and pH 9.5 were made. Also, the influence of the degree of oxidation of galena surface on the detachment force was studied. Instantaneous contact angles were measured at the moment of air bubble disruption in the galena grain-air-bubble-water system and galena grain-air bubble-potassium ethyl xanthate solution. Using the Young's equation and the instantaneous contact angles, the nondispersion component of galena surface free energy was calculated and compared with that obtained from the detachment force values. From the comparison, it is concluded that the changes of detachment force occur particularly under the influence of nondispersion component changes.

Adhesion of an Air Bubble to Quartz Surface in Aqueous Solution of Aliphatic Amine Hydrochloride

Abstract Measurements of the force of air bubble detachment from a quartz surface in aqueous solutions of decylamine hydrochloride (DAC1), dodecylamine hydrochloride (DDAC1) and tetradecylamine hydrochloride (TDAC1) were made in the concentration range from 0 to 200mg/dm3. At the same time, the instantaneous contact angle for the system quartz-air bubble-aqueous solution of aliphatic amine hydrochloride was photographed at the moment of detachment. Wetting contact angles for the system quartz-air bubble-aqueous solution of DDAC1 were also measured. On the basis of the measured values of the instantaneous angle and surface tension of the solutions studied, the changes of polar components of surface free energy of quartz/monolayer water film under the influence of adsorption of molecules of aliphatic amine hydrochloride (RAC1) from aqueous solution were calculated and compared with the literature data. Using these data, the force of air bubble detachment from the quartz surface in the presence of RAC1 was also calculated and compared with the measured force, obtaining a good agreement. From the studies and calculations it appears that a little addition of RAC1 to water considerably changes the stability of the system quartz-air bubble-solution, and that this change is first of all caused by reduction of a polar component of the surface free energy of quartz/monolayer water film as a result of adsorption of RAC1 molecules in the negative places of such a surface. As a result of RAC1 adsorption this surface becomes similar to that of paraffin.

The effect of n-alkanes on the force of air bubble detachment from the surface of graphite in water

Measurements of the force of air bubble detachment from graphite surface wetted with n-alkane (in homologous series from hexane to hexadecane) in water were carried out; it was found that the detachment force as a function of the chain length of the hydrocarbons changes discretely, probably because of a different film structure of even hydrocarbon and the neighboring odd one. It was shown that the detachment force depends on the film thickness and that an optimal thickness exists for every n-alkane, for which maximal stability of a three-phase systems occurs. The stability of the system graphite/ n-alkane film—air bubble—water can well be calculated on the basis of the contact angle value in this system from the equation relating the magnitude of the detachment force with the area of the contact plane, the size of air bubble, and contact angle value.

The effect of n-alcohols on the force air bubble detachment from the surface of sulphur and graphite

The force of air bubble detachment from sulphur and graphite surfaces was measured in aqueous solutions of methanol, ethanol and propanol in the concentration range 0 – 300 mg/dm 3. At the same time the angle was measured at the moment of rupture of the systems sulphur—air bubble—solution and graphite—air bubble—solution. From the results obtained it was found that the detachement force decreased as a function of alcohol concentration in water due to the occurrence of polar interactions at the sulphur—solution and graphite—solution interfaces. It was also found that the changes in the contact angle at the moment of rupture were similar to changes in the equilibrium contact angle in these systems. Thence, changes of F 0 values as a function of alcohol concentrations in water were calculated from the equation connecting the detachment force with the surface tension of the solution, the size of the contact plane area, the diameter of the bubble and the equilibrium contact angle. Calculated changes agreed with those found experimentally.

Force of air bubble detachment from a quartz surface wetted with n-alkane in aqueous solutions of methanol and propanol

Measurements of the force required to detach air bubbles from a quartz surface wetted with n-alkane in aqueous solutions of methanol and propanol were carried out. Aliphatic hydrocarbons in series from hexane to hexadecane as well as aqueous solutions of methanol and propanol in the concentration range from 0 to 100% were tested. From the results obtained, it was found that the presence of small amounts of polar liquids in water causes both an increase in the stability of n-alkane film on a quartz surface and an increase in the stability of air bubble contact with a quartz surface.

Detachment force of air bubble from the solid surface (sulfur or graphite) in water

Measurements of the force of air bubble detachment from sulfur and graphite surfaces in water were made. Simultaneously, the grain-air bubble system was photographed at the moment of detachment to measure the instantaneous contact angle. The results obtained are discussed as the relationship between detachment force and contact angle for various contact plane radii and air bubble volumes. The measured detachment force values were compared with those calculated from the contact angles. The relationship between the detachment force and the interfacial free energies of the phases in contact was derived for the systems tested.

The effect of n-alkanes on the force of air bubble detachment from a quartz surface in water

Measurements of the force of air bubble detachment from a quartz surface wetted with aliphatic hydrocarbons in water were carried out. Hydrocarbons in the homologous series from hexane to hexadecane were used. From the measurements, it was found that the contact of an air bubble with the quartz surface is strengthened under the influence of hydrocarbons This strengthening depends on the nature and amount of the hydrocarbon on the quartz surface. It was also found that differences exist between even and odd hydrocarbons in their influence on the stability of the system quartz—air bubble—water.