The nucleation of normal-eicosane crystals from solution in normal-dodecane in the presence of homologous impurities

Studies have been made of the nucleation of crystals of n-eicosane from solutions in n-dodecane both in the pure state and in the presence of the neighbouring homologues; n-octadecane, n-nonadecane, n-heneicosane and n-docosane. Impurity incorporation studies yielded distribution coefficients, λ 1 in the early stages of precipitation decreasing to λ 1 in the growth stage. This high degree of incorporation in the early stages implies that the homologues should play a significant part in the nucleation process. This conclusion is confirmed by nucleation studies which show that the addition of the homologous impurities yields an increase in the width of the metastable zone and in the evaluated surface free energy of the resulting solid. The higher molecular weight homologues yield a greater effect than the lower molecular weight homologues. The homologues are thus defined as efficient nucleation inhibitors. The characteristics of the product crystals are in accord with this interpretation.