本文指出了一种离子交换体系的两相中有U(Ⅳ)存在时的酸度研究法。测定了与0.18-0.27NHCl平衡的磺酸型交换树脂中U(Ⅳ)的平均价n_(U(Ⅳ))为2.8、H~+浓度RH_(U(Ⅳ))为0.15当量/升树脂床,U(Ⅳ)主要U(OH)~(3+)存在;0.50NHCl时,n_(U(Ⅳ))为3.6,RH_(U(Ⅳ))减为0.10当量/升例脂床,UCl~(3+)仅占树脂中U(Ⅳ)总量的5％以下。讨论了不同U(Ⅳ)浓度时两相中的酸度关系,得出了适当高的溶液酸度有利于RH_(U(Ⅳ))的减低的结论并给予了解释。 This paper points out the method of acidity in the presence of U (IV) in two phases of an ion exchange system. The average value of U (Ⅳ) in the sulfonic acid exchange resin with 0.18-0.27NHCl was determined to be 2.8 and the H_ (+) U (Ⅳ) was 0.15 eq / L resin bed U (Ⅳ) and U (Ⅳ) were mainly present in U (Ⅳ) and U (OH) ~ (3+) respectively. When 0.50NHCl was added, (3+) only accounts for less than 5% of the total amount of U (IV) in the resin. The relationship between the acidity of two phases at different concentrations of U (Ⅳ) is discussed, and the conclusion that moderately high solution acidity is favorable for the reduction of RH_ (U (Ⅳ)) is given and explained.