Abstract

Removal of zinc and cadmium from highly saline solutions by hydroxide precipitation is discussed. Experimental solubilities of zinc and cadmium in highly saline solutions were compared to modeled results obtained using Pitzer’s approach. An amphoteric character of zinc and cadmium and an influence of chloride ion on the concentration of dissolved metals were investigated. In order to avoid errors linked to pH measurements in concentrated aqueous solutions, the method of calibration of glass pH electrodes was developed and evaluated. The method uses easily prepared buffers whose pHs were determined with the Pitzer ion-interaction approach. The presented investigations address two issues of high significance in industrial wastewater treatment, namely: precise pH measurements and rigorous modeling of highly saline wastewaters. The results can be implemented in the treatment of hydrometallurgical wastewaters such as zinc refinery wastewater. Additionally, an implementation of the presented investigations is not limited to wastewater treatment but can easily be extended to other high-chloride metallurgical processes wherein the pH measurements in highly saline streams are required.

Graphical Abstract

中文翻译：

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重金属氢氧化物沉淀中高浓度氯化物对pH控制的影响

摘要

讨论了通过氢氧化物沉淀从高盐溶液中去除锌和镉。将锌和镉在高盐溶液中的实验溶解度与使用Pitzer方法获得的模拟结果进行了比较。研究了锌和镉的两性特征以及氯离子对溶解金属浓度的影响。为了避免与浓水溶液中的pH测量有关的错误，开发并评估了玻璃pH电极的校准方法。该方法使用易于制备的缓冲液，其pH值是通过Pitzer离子相互作用法确定的。提出的研究解决了在工业废水处理中非常重要的两个问题，即：精确的pH测量和高盐度废水的严格建模。该结果可用于处理湿法冶金废水，例如炼锌厂废水。另外，所提出的研究的实施方式不限于废水处理，而是可以容易地扩展到需要在高盐溶液中测量pH值的其他高氯化物冶金工艺。

图形概要