MECHANISM OF THE EXTRACTANT LOSS IN LANTHANIDE EXTRACTION PROCESS WITH SAPONIFIED ORGANOPHOSPHORUS ACID EXTRACTION SYSTEMS — II: FORMATION OF AQUEOUS AGGREGATES
作者:
Dujin Wang,
Yan Li,
Jinguang Wu,
Guangxian Xu,
期刊:
Solvent Extraction and Ion Exchange
(Taylor Available online 1996)
卷期:
Volume 14,
issue 4
页码: 585-601
ISSN:0736-6299
年代: 1996
DOI:10.1080/07366299608918358
出版商: Taylor & Francis Group
数据来源: Taylor
摘要:
Organophosphorus acids, including di(2-ethylhexyl) phosphoric acid (D2EHPA), 2-ethyIhexyI phosphonic acid mono 2-ethylhexyl ester (PC88A), and di(2-ethylhexyl) phosphinic acid (P229) form reversed micelles (d=20-100A) or water-in-oil (w/o) microemulsions (d=100-2000 A) in n-heptane when they are saponified with concentrated alkalis, such as NaOH, KOH and NH3H2O. After equilibrating with water or solution containing europium, some extractant and diluent in the saponified organic phase transfers into the aqueous phase, and some water solubilized in the w/o microemulsion returns to the aqueous phase. Dynamic light scattering (DLS) results indicate that aggregates within the range of micelles or microemulsions are formed in the equilibrated aqueous phase. The normal micelle or o/w microemulsion has a non-polar core that solubilizes n-heptane. Therefore, the formation of aqueous aggregates leads to extractant and diluent loss in the extraction procedure. FT-IR spectra also confirm the presence of extractant and diluent in the final aqueous phase. Inorganic salts (NaCl, NaN03or Na2SO4)
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