Abstract
This paper reports results on the extraction behavior of mercury (II) from dilute hydrochloric acid solutions using mono‐ and di‐sulphur analogs of bis(2,4,4‐trimethylpentyl)phosphinic acid, namely, bis(2,4,4‐trimethylpentyl)monothiophosphinic acid (CYANEX 302) and bis(2,4,4‐trimethylpentyl)dithiophosphinic acid (CYANEX 301). The effect of various parameters such as, concentrations of mineral acid, metal ion, extractant, and the nature of the diluent on the extraction of mercury (II) has been investigated. The results clearly demonstrate that CYANEX 302 and CYANEX 301 do not behave as cation‐exchange extractants but as solvating extractants, owing to the strong affinity of sulphur atom of the extractant for the soft metal ion mercury. The extraction equilibrium of mercury (II) can be represented as:
Acknowledgments
This work is supported by the Ministry of Environment and Forests, Government of India, New Delhi. One of the authors, TF would like to acknowledge CSIR, New Delhi, for the award of senior research fellowship.