铁离子对磷酸二氢钾结晶过程的影响

Effect of impurity Fe(Ⅲ) on crystallization process of potassium dihydrogen phosphate

采用激光散射法测定了含有不同铁离子含量的磷酸二氢钾水溶液介稳区宽度,在介稳区宽度内测得不同铁离子含量对磷酸二氢钾结晶生长速率的影响。并采用间歇冷却结晶法在未加晶种条件下测定了铁离子对磷酸二氢钾结晶形态、晶体堆积密度及晶体铁含量的影响。结果表明:随着掺入铁离子含量的增大,结晶介稳区宽度变宽,生长速率下降;晶体由规则棱柱状变为针状,晶体出现开裂,光泽不均匀;晶体堆积密度逐渐减小,包裹铁含量逐渐增大。

The crystallization metastable zone width numbers of potassium dihydrogen phosphate （KDP） solution with different contents of Fe （ Ⅲ ） were determined by laser light scattering method.Effect of Fe （Ⅲ ） with different contents on crystal growth rate of KDP was studied.Effects of Fe （Ⅲ） on the crystallization morphology, bulk density, and Fe （ Ⅲ ） content of the KDP crystals were investigated by means of batch crystallization process and without crystal seed added in the system. Results showed that with the increase of Fe （ Ⅲ ） content,the metastable zone of KDP was widened and the growth rate decreased ; the KDP crystal morphology changed from regular prism to speculate, the cracking of the crystal happened, and the luster of the crystal became uneven ; and the crystal bulk density decreased and Fe （Ⅲ） content of the KDP crystals increased gradually.