氯化物型三价铬镀铬液中硼酸的分析方法  

Analysis of boric acid in chloridic trivalent chromium electroplating bath

作　　者：罗小平[1] 郭崇武[1] 李小囝 

机构地区：[1]广州超邦化工有限公司,广东广州510460

出　　处：《电镀与涂饰》2017年第4期222-224,共3页Electroplating & Finishing

摘　　要：为了解决铵盐对测定硼酸的干扰问题,制定了测定氯化物型三价铬镀铬液中硼酸的新方法。用草酸钾掩蔽Cr^(3+)和Fe^(3+)离子。用甘露醇与硼酸反应生成较强的配合酸,以溴麝香草酚蓝作指示剂(变色范围为pH=6.0~7.6),用氢氧化钠标准溶液滴定配合酸。测定结果的相对平均偏差为0.45%,回收率为99.88%~101.24%。A novel method for determining the content of boric acid in a chloridic trivalent chromium plating bath was established to eliminate the interference of ammonium salt. Cr3＋ and Fe3＋ ions are masked by potassium oxalate. Boric acid is reacted with mannitol to produce a complex acid whose acidity is stronger than boric acid, and then the complex acid is titrated by standard NaOH solution with bromothymol blue as indicator with a color change range from pH 6.0 to 7.6. The method has a relative average deviation of 0.45% and a recovery ranging from 99.88% to 101.24%.

关 键 词：三价铬镀铬液 氯化铵 硼酸 配合酸 酚酞 溴麝香草酚蓝 滴定分析 

分 类 号：TQ153.2[化学工程—电化学工业] O655.25[理学—分析化学]