MECHANISM OF THE PREPARATION OF INSOLUBLE COMPOUNDS BY LOCAL GROWTH IN AQUEOUS-SOLUTION

Stable and controlled-size particles of very insoluble products can be prepared by a method of local growth. The growth takes place at the i nterface between a solid reactant and a solution containing the other reacting compound. The mechanism of this process is studied taking hex acyanoferrates as examples. The influence of parameters such as the na ture of the starting materials, concentration and temperature is studi ed by potentiometric and radiochemical methods, and by optical microsc opy. The results are interpreted by a mechanism based on osmosis. From this mechanism, experimental conditions for the preparation of insolu ble compounds by local growth can be predicted, using water activities calculations.