The precipitation of calcium sulphate dihydrate from aqueous solution: Induction periods, crystal numbers and final size

摘要: The precipitation of calcium sulphate dihydrate was studied from solutions concentration (C) 0.02 to 0.24 M, supersaturation (S) 1.5 16, by optical microscopy and chemical analysis; induction periods, final crystal lengths numbers were measured. periods (t) decreased 12000 3 sec over this range; t varied with C according the relation = Kt/▿C4. (N) N KNC7. 0.15 cm range. precipitations occured through a heterogeneous nucleation process. Heterogeneous nuclei formed immediately after mixing then grew, slow growth process, small crystallites during periods: these latter grew more rapid process large crystals. “reaction order” for 9–10; “order” 4.