REMOVAL OF CADMIUM BY ANION EXCHANGE IN A WET PHOSPHORIC ACID PROCESS. PART 1: CHEMISTRY
作者:
T.T. Tjioe,
P. Weij,
J.A. Wesselingh,
G.M. van Rosmalen,
期刊:
Solvent Extraction and Ion Exchange
(Taylor Available online 1988)
卷期:
Volume 6,
issue 2
页码: 335-360
ISSN:0736-6299
年代: 1988
DOI:10.1080/07366298808917941
出版商: Taylor & Francis Group
数据来源: Taylor
摘要:
The removal of cadmium ions by anion exchange from 55-65 w% H3PO4at 90°C in the presence of small amounts of halides was investigated. Iodide appears to be the most effective additive. Cd distribution coefficients, K = [CD]/[Cd] (w/w), of a few thousand were obtained at equilibrium concentrations of a few hundred ppm iodide in the solution. The stability constants of CdIi. complexes in 55-65 w% H3PO4are much higher than in diluted aqueous solutions and the negatively charged CdIi. complexes have a high affinity for the amine groups of the resin. Stability constants Bi. of CdIi. complexes in concentrated phosphoric acid were determined by using differential pulse polarography. A tentativedescription of the complexation and ion-exchange equilibria assuming adsorption of only one negatively charged Cd species(CdI3−) or CdI42−) is presented. The removal of I-from the phosphoric acid solution exchange was also investigated. Iodide distribution coefficients of about 300 w/w were obtained for a weekly basic resin at an iodide loading of 0.22 mol/kg dry resin.
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