Highly Efficient Extraction of Cadmium(II) in Nitrate Medium by Quarternary Ammoniums

Abstract

The solvent extraction of cadmium(II) from nitrate medium was studied. The using extractants were quaternary ammonium-based room temperature ionic liquid Aliquat 336 in either the chloride [(C 8 H 17 ) 3 CH 3 N + ·Cl - ], thiocyanate [(C 8 H 17 ) 3 CH 3 N + ·SCN - ] and hydrogenophosphate forms, diluted in the kerosene. The effects of different parameters such as equilibration time, initial pH, O/A molar ratio (n extractant /n Cd ), initial extractant concentration and ionic strong on extraction of cadmium(II) were investigated. The extraction yields of cadmium(II) increase with increasing initial pH and initial extractant concentration. The stoichiometry of the extracted species was determined on the basis of slope analysis. The effect of various salts such as KSCN and NaNO 3 in the feed solution within the concentrations of 10 to 100 mM on extraction of cadmium(II) was studied at optimal initial pH = 6.2. The relation between the percentages of the extracted species ( ) and the extraction yields were investigated by a calculation program using CHEAQS V. L20.1. The results showed that the decrease of the extraction yield of Cd(II) was related with the decrease gradually of percentage of cadmium(II) free and the increase of percentage of and species with the addition of KSCN. More the hydrophobic character of the extractant is high, more the extraction is better. The metal ion was stripped out satisfactorily using nitric acid as stripping agent, in one step.