THE INFLUENCE OF SURFACTANTS ON THE CRYSTALLIZATION OF CALCIUM-OXALATE HYDRATES

The influence of sodium dodecyl sulphate, SDS, dodecyl ammonium chlori de, DDACl and octaethylene glycol mono-n-hexadecyl ether, C(16)EO(8), On the crystallization of calcium oxalate from 0.3 molar sodium chlori de solutions is discussed. Under the given experimental conditions the thermodynamically stable monohydrate, COM was the predominant crystal form. Both ionic surfactants inhibited growth and aggregation of COM and, by preferential adsorption at different crystal faces, induced di fferent habit modifications. In addition, micellar solutions of SDS pr omoted crystallization of the metastable calcium oxalate dihydrate, GO D. The nonionic surfactant, C(16)EO(8), Stimulated nucleation and/or i nitial crystal growth of COM, most probably by providing active center s for heterogeneous nucleation.