制革生产用水钙镁离子含量测试方法优化

Optimization of Water Hardness Test Method for Leather-making

常规水硬度测试化学方法使用铬黑T指示剂,当水中镁离子含量低,钙离子浓度高时,终点显色会受影响。为了使显色明显,需要提前在缓冲溶液中加入少量硫酸镁,操作复杂,过程繁琐。实验选用KB混合指示剂(酸性铬蓝和茶酚绿以不同比率混合配制),适合制革用水中不同浓度钙离子含量的水硬度测定,加标回收率满足允许范围,是一种简便易操作的测试方法。

The Chromium black T indicator was used in the traditional measurement method.When the content of magnesium ion and in water appears low and the concentration of calcium ion shows high,the end-point color will be affected.In order to make the end-point color obvious,it is necessary to add a small amount of magnesium Sulfate in the buffer solution in advance,which would bring complicated and tedious operation.The mixed indicator of KB which was prepared with acid Chrome blue and tea green as different ratio,can solve the problem.It is suitable for the determination of water hardness in different concentrations of calcium ion in water.The recovery rate of the standard meets the allowable range.It is a simple and easy test method to operate.