沉淀分离-滴定法测定碱性锌镍合金镀液中的锌含量

Determination of zinc content in an alkaline zinc–nickel alloy electroplating bath by titrimetry after precipitation separation

在pH为4～6的条件下用丁二酮肟沉淀分离碱锌锌镍合金镀液中的镍离子,再用抗坏血酸掩蔽铁杂质,氟化钠掩蔽铝杂质,硫脲掩蔽铜杂质,在pH=5.4的条件下,以二甲酚橙作为指示剂,用EDTA标准溶液滴定锌。本法的相对平均偏差为0.35%,回收率为98.07%～99.32%,操作安全,无污染。

Nickel ions in alkaline Zn–Ni alloy electroplating bath are precipitated by dimethylglyoxime at pH 4-6 and then separated. Fe, Al and Cu impurities in the bath are masked by ascorbic acid, sodium fluoride and thiourea, respectively. Zinc is then titrated by EDTA standard solution with xylenol orange as indicator at pH 5.4. The method has a relative average deviation of 0.35% and a recovery ranging from 98.07% to 99.32% with the advantages of safe operation and no pollution.