Study on salt dissolution and salt effect is important for development of chemical technology. The solubility of terephthalic acid disodium in water at different temperatures was measured by using equilibrium method at atmospheric pressure. For seven organic salts and three inorganic salts

the dissolving process of two salts in water was examined under the normal pressure and 298.15 K. It is found that the feeding sequence affects the dissolution of two salts. When difficult ionized salt is dissolved first and easily ionized salt is dissolved later

the dissolution rate of the latter does not change obviously; when easily ionized salt is dissolved first

the dissolution rate of difficult ionized salt is significantly reduced and the solubility decreases. Fixing the amount of one salt

the amount of another salt dissolved in a period of time is defined as the quasi-solubility. The determination of quasi-solubility of terephthalic acid disodium in different concentrations of sodium citrate solution provides the basis for purification of chemical products.