Comprehensive Experimental Design of Phase Equilibrium in the Na+,K+//CO32-,SO2--H2 O Quaternary Water-salt Systems
The abstract and complex nature of phase equilibrium theory often makes it difficult to understand,which can bring challenges for teaching and learning the contents of phase law and phase diagrams.To address this,we design a comprehensive experiment focusing on phase equilibrium in a quaternary water-salt system.Using the isothermal solution equilibrium method,we study the solid-liquid equilibria of the interactive quaternary system Na+,K+//CO32-,SO4--H2O at 353~373 K and draw the corresponding isothermal dry base phase diagram and water diagram.This phase diagram is then used to guide the process design of solution-evaporation crystallization of alkali ash,where we optimize the crystallization parameters at high CO32-concentrations and recycled Na2SO4.By integrating the measurement of phase equilibrium data,the drawing of phase diagrams,and the analysis of phase diagrams,our experiment provides a practical way to enhance students'ability to solve engineering problems using basic phase equilibrium theory.Furthermore,it helps students master theoretical knowledge,stimulates their interest in scientific research,and cultivates a spirit of exploration