Coefficients, D2/1 of cocrystallization of M2+ ions with ZnSeO4·5H2O at 40 °C and ZnSeO4·H2O at 50 °C and their dependences on various physicochemical and crystal-chemical factors

► We determined coefficients D2/1 of M2+ions with ZnSeO4 hydrates at 40 and 50 °C. ► They are hardly affected by temperature and changing crystal structure of ZnSeO4 hydrates. ► Equations for D2/1 estimation derived based on its dependences on some factors. ► A scheme has been proposed for crystallization removal of most M2+ ions from ZnSeO4.