The results of an investigation of the effect of Al₂(SO₄)₃ and K₂SiO₃ impurities on the crystallization of K₂SO₄ from aqueous solutions are described and discussed. The metastable zone width (MSZW) of K₂SO₄ aqueous solutions, without and with known concentrations of the impurities, saturated at 40 and 60 °C is determined, using ultrasonic sensor by the controlled solution cooling method at predefined cooling rates R. It is observed that the value of the MSZW of the two types of saturated solutions increases with an increase in the cooling rate R and the concentration C_i of the two impurities. The experimental data of the dependence of MSZW on cooling rate and impurity concentration are analyzed by an approach based on the classical 3D nucleation theory. The results showed that: 1) both impurities suppress the formation of 3D nuclei by physically blocking the active sites on their surfaces, 2) Al₂(SO₄)₃ impurity is more effective than K₂SiO₃ impurity, and 3) the purity of the K₂SO₄ crystals is insignificantly affected by these impurities, but the morphology and size of the obtained crystals are influenced strongly by Al₂(SO₄)₃ impurity.

中文翻译：

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Al2（SO4）3和K2SiO3杂质对K2SO4从水溶液中结晶的影响

描述并讨论了Al ₂（SO ₄）₃和K ₂ SiO ₃杂质对K ₂ SO ₄从水溶液中结晶的影响的研究结果。使用超声传感器通过控制溶液冷却方法，以预定的冷却速率R，确定在40和60°C下饱和的，无杂质和已知杂质浓度的K ₂ SO ₄水溶液的亚稳区宽度（MSZW）。可以看出，两种类型的饱和溶液的MSZW值随冷却速率R的增加而增加。以及两种杂质的浓度C _i。通过基于经典3D成核理论的方法，分析了MSZW对冷却速率和杂质浓度的依赖性的实验数据。结果表明：1）两种杂质均通过物理阻断其表面上的活性位点来抑制3D核的形成； 2）Al ₂（SO ₄）₃杂质比K ₂ SiO ₃杂质更有效，并且3）纯度这些杂质对K ₂ SO ₄晶体的组成影响不大，但是Al ₂（SO₄）₃杂质。