In order to solve the problem for evaluating the separating effect and mixing effect of cation and anion resins in a mixed bed

the definisions of separation coefficient and mixing coefficient have been put forward

the related theoritical basis being presented

and the calculation method being given.Through measurement of the separation coefficient and the mixing coefficient for cation and aion resins used in a mixed bed and produced from three enterprises at home and abroad

the evaluation indices and selection method of resins used in the mixed bed have been given:selecting cation and anion lesins with good uniformity based on particle size difference;under prerequisite of having allowable mixing rate of resins and ensuring the separation coefficient to be positive value

cation and anion resins with little mixing coefficient have to be selected.