What is the azeotrope principle?

Azeotrope: A mixture formed by two (or several) liquids at a constant boiling point is called an azeotropic mixture. It refers to a mixed solution that is in equilibrium, with the same composition in both the gas phase and the liquid phase. 　　The corresponding temperature is called the azeotrope temperature or azeotrope point.

Azeotropic distillation, also known as constant-boiling-point distillation, is a distillation process that utilizes the property of components in a mixture to form azeotropes for separation. Typically, an azeotrope-forming agent (or entrainer) is added to the solution to be separated, so that it forms an azeotrope with one or two components of the solution, thereby increasing the relative volatility between the components to be separated and facilitating the separation process. If the azeotrope formed is a volatile top product, then the bottom of the column theoretically yields a pure component; such a system is referred to as a system with a minimum azeotrope. If the azeotrope is a non-volatile bottom product, then a pure component can theoretically be obtained at the top of the column; such a system is referred to as a system with a maximum azeotrope. When two liquids with similar properties are mixed, the resulting solution behaves like an ideal system; they dissolve in each other over a wide range of temperatures, and their vapor pressures obey Raoult’s law. The azeotrope phenomenon occurs because the molecular structures of the components constituting the solution are not similar, leading to deviations from ideal solution behavior upon mixing. If the vapor pressure of the solution deviates negatively from that of an ideal solution, that is, when the activity coefficient is less than 1, a maximum azeotrope is formed ； If the vapor pressure of the solution deviates positively from that of an ideal solution, that is, if the activity coefficient is greater than 1, then a minimum boiling azeotrope is formed. Principle of azeotropic distillation separation: It is essentially the same as extractive distillation; the difference is that the azeotrope former (entrainer, carrier) not only affects the relative volatility of the components in the original solution but also forms an azeotrope with one or more of those components. http://zy.zhku.edu.cn/yjhx/syjx/syjc/2/3/3_6.pdf

Is azotropy related to the ratio of the two substances?

Yes. . . . . . . . . . . .

Azeotropic distillation is generally used to separate several components with similar boiling points that are difficult to separate by ordinary distillation. A third component is added to the mixture to form azoles with one or more of the components present (either with a higher or lower boiling point), thereby achieving separation. For example, in the production of acrylic acid, since the boiling points of acrylic acid, acetic acid, and water are close to each other, the use of conventional distillation equipment would be costly; therefore, toluene is added so that toluene-acetic acid and toluene-water form azeotropes which are distilled out from the top of the tower, while the acrylic acid, which is relatively more alcoholic, remains at the bottom of the tower.