The basic principle of special flotation (1)

(I) Ion Flotation The basis of ion flotation is the interaction of surfactants at the liquid-vapor interface and the interaction between the target and the surfactant. If the isolate is the surfactant itself, then only the former effect.
A Surfactant at the liquid-vapor interface The oppositely polar surfactant molecules are aligned at the water-air interface or water-oil interface, with the polar end facing the water and the non-polar end facing the gas or oil, forming a positive Adsorption reduces the surface energy of water significantly.
The adsorption of the dilute solution can be expressed by Gibbs adsorption. The adsorption amount at each concentration can be calculated by the Gibbs equation by measuring the curve (as shown in Fig. 1):

In the formula, LM, MN--the length of the midline segment.

B Factors Affecting the Adsorption Amount of Surfactant The amount of adsorption is directly related to the sorting efficiency of ion flotation. The factors affecting the size of the cockroach generally have the following three aspects.
a Structure of the surfactant The structure of the surfactant includes a polar group and a non-polar group structure. The polar group mainly determines the cross-sectional size of the surfactant molecule and the action form on the target ion molecule, thus directly affecting the maximum adsorption amount Γ _∞ ; the non-polar group mainly determines the hydrophobic property of the agent, ie, the surface activity, and the molecular structure also affects the critical micelle. Formation and critical micelle concentration (CMC) size. The increase in the number of polar groups or the number of double and triple bonds in the surfactant will reduce the hydrophobicity of the surfactant and will therefore reduce the attachment of the surfactant at the liquid-vapor interface. [next]
b Surfactant concentration The ratio of adsorbed amount to surfactant concentration Γ/C is called the enrichment ratio, also known as the partition coefficient. The enrichment ratio is shown in Figure 2 as a function of surfactant concentration. At low concentrations, the enrichment ratio is higher than Γ/C and begins to decrease after a certain concentration. When a small amount of surfactant is added, the surfactant molecules or ions are mostly adsorbed at the liquid-vapor interface, and the amount remaining in the solution is extremely small, and the free energy of the system is minimized. As the amount of surfactant increases, the adsorption at the liquid-gas interface gradually becomes saturated. The relative amount remaining in the solution gradually increases, and the enrichment ratio starts to decrease. When the adsorption saturation is reached at the liquid-vapor interface, the excess surfactant remains in the solution, and the enrichment ratio is further lowered. When the critical concentration (CMC) of the critical micelle is reached, although the concentration increases, the concentration of the molecular or ionic component does not increase, and the adsorption density and surface energy at the liquid-vapor interface do not change, so the Γ/C is rapidly Lower, there is a break point. To achieve high sorting efficiency, control the surfactant concentration below CMC. Because of the high enrichment ratio of surfactants at low concentrations, ion flotation is particularly suitable for the separation of low concentration materials.

The relative partition coefficient a _{AB of the} two surfactants A and B is defined as ΓA and ΓB are the adsorption amounts of components A and B at the liquid-vapor interface at a solution concentration of C _A and C _B , respectively. The separation of B from A must be carried out under the maximum value of a _AB , and therefore should be sorted under CMC conditions which are just slightly lower than the A substance (relatively large).
c Media environment affects media environment effects including ionic strength, pH, medium temperature, etc. Generally, an increase in ionic strength or a decrease in temperature will increase the partitioning ratio of the surfactant at various interfaces. On the other hand, an increase in ionic strength can also promote the formation of micelles, thereby reducing the enrichment ratio. In addition, the ionic strength also affects the stability of the foam, the loss of water between the foams, etc., so the influence of the medium environment factors on the adsorption of the surfactant at the liquid-gas interface is complicated and needs to be treated specifically.
C The interaction between the surfactant and the solute The form of action between the surfactant and the target as a collector is roughly classified into the following three types.
a Electrostatic association ionic surfactant can adsorb to form an electric double layer at the liquid-vapor interface, and the target ions with opposite charge signs are concentrated in the dense layer and diffusion layer of the electric double layer by electrostatic attraction, and enter the foam with the bubbles. The layer forms a two-phase foam (Fig. 3). Due to electrostatic attraction and molecular thermal motion, a diffused electric double layer is formed, and the distribution of the target ions in the diffused electric double layer is according to the Boltzmann equation:

In the formula—the amount of adsorption of anti-ion ions;
C———the concentration of anti-ion ions in the solution;
z———the valence of the anti-ion ions;
Ψ _T ——— the potential generated by the adsorption of the surfactant;
K——— a constant for converting the number of moles per unit volume into the number of moles per unit area;
Φ—the potential generated by the adsorption of the characteristic;
k———Boltzmann constant;
T———absolute temperature;
e———Electronic charge.

Storage Ring

The storage ring of coil winding machine is one of the most important parts used to complete the work of storage and winding.