ISSN:
1432-1130
Source:
Springer Online Journal Archives 1860-2000
Topics:
Chemistry and Pharmacology
Notes:
Abstract A new method for the separation and determination of trace amounts of cadmium and zinc in water as their thenoyltrifluoroacetone (TTA) complexes with dibenzo-18-crown-6 (DB18C6) in o-dichlorobenzene has been established by means of synergistic extraction and back-extraction combined with atomic absorption spectrometry. The effect of various factors (synergism with TTA and DB18C6, shaking time, composition of the extracted species, and mutual separation etc.) on the extraction and back-extraction of cadmium and zinc has been in- vestigated. When the mixtures were extracted for 4 min at pH 4.9, only zinc was extracted quantitatively, whereas cadmium remained in the aqueous phase. After the phases were separated, cadmium was again extracted quantitatively at pH 7.5. Then, the two phases were each shaken with 0.05–0.1 mol/l HCl in order to back-extract cadmium and zinc from the organic phases; the ions were determined individually by atomic absorption spectrometry. In the process cadmium and zinc TTA chelates in o-dichlorobenzene form stable adducts with DB18C6 (Cd(TTA)2 ⋅ nDB18C6 and Zn(TTA)2 ⋅ nDB18C6, n=0∼2). The stability constants (βn) of the adducts determined by means of the curve fitting method were log β1=4.62 and log β2=6.74 for cadmium, and log β1=3.48 and log β2=5.18 for zinc.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1007/s002160050111
Permalink