Liquid-liquid extraction of some rare earth metal ions by polyoxyalkylene systems

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" Liquid-liquid extraction of some rare earth metal ions by polyoxyalkylene systems "
A.-E. A. Al-Naser

Document Type	:	Latin Dissertation
Language of Document	:	English
Record Number	:	1112893
Doc. No	:	TLpq304347315
Main Entry	:	A.-E. A. Al-Naser
Title & Author	:	Liquid-liquid extraction of some rare earth metal ions by polyoxyalkylene systems\ A.-E. A. Al-Naser
College	:	King Fahd University of Petroleum and Minerals (Saudi Arabia)
Date	:	1996
student score	:	1996
Degree	:	M.S.
Page No	:	146
Abstract	:	Polyoxyalkylene systems, namely, polypropylene glycol(PPG-1025), polyethylene glycol(PEG-600) and polybutadieneoxide(PBDO-700) dissolved in either nitrobenzene or 1,2-dichloroethane have been tested as prospective extractants for some lanthanide metal ions usd\rm(Pr\sp{3+},\ Eu\sp{3+},usd and Er from their aqueous solutions in the presence of picrate lipophilic anions. The metal ions were quantified before and after extraction using inductively coupled plasma emission spectrophotometry technique. The percent extraction and the distribution coefficient have indicated that pH of the aqueous phase, picrate concentration and the organic solvent are the major parameters that affect the extraction efficiency of the metal ions. The optimum pH range was found to be 3.5 to 5.5 and the picrate concentration should be as high as possible, however a picrate concentration of about 0.05M proved to be adequate for a near quantitative extraction. In all cases, nitrobenzene enhanced a higher percent extraction compared to 1,2-dichloroethane. The efficiency of the polyoxyalkylene systems to extract certain lanthanide metal ions was in the order PBDO-700 > PPG-1025 > PEG-600 when nitrobenzene was the organic solvent and in the order PPG-1025 > PBDO-700 > PEG-600 when 1,2-dichloroethane that has a lower dielectric constant, used as the solvent in the organic phase. The extractability of PPG-1025 towards the lanthanide metal ions was in the order usd\rm Pr\sp{3+}>Eu\sp{3+}>Er\sp{3+}usd irrespective of the organic solvent used. The stoichiometry of the extracted polyoxyalkylene ion-pair with the lanthanide metal ions has been estimated. Each mole of the metal ions is associated with three moles of picrate anions and 13 to 14 moles of the propyleneoxide units in the case of PPG-1025, and about 10 moles of ethyleneoxide units in the case of PEG-600 and 10 moles of butadieneoxide units in the case of polybutadieneoxide-700.
Subject	:	Chemistry
	:	erbium
	:	europium
	:	Organic chemistry
	:	praseodymium
	:	Pure sciences