Complexation of lanthanides with crown ether carboxylic acids and its applications in analytical chemistry

Thesis/Dissertation · Sun Jan 01 04:00:00 EST 1989

OSTI ID:5941926

Tang, Jian

The extraction characteristics of trivalent lanthanides by three crown ether carboxylic acids of different lipophilicities were investigated. Extraction was found to be independent of anions and strongly dependent on pH. Quantitative extraction of lanthanides was observed in the pH range of 6-8 by all three crown ether carboxylic acids: sym-dibenzo-16-crown-5 oxyacetic acid (I), 2-(sym-dibenzo-16-crown-5-oxy)hexanoic acid (II), and 2-(sym-dibenzo-16-crown-5-oxy)stearic acid (III). Results of competitive experiments indicated that this extraction system was highly selective for lanthanides relative to other major ionic species, such as the alkali metal ions, the alkaline earth metal ions, and transition metal ions. The extraction method has been applied to the determination of low levels of lanthanides in natural waters and in biological materials. Sym-dibenzo-16-crown-5-oxyacetic acid had insufficient lipophilicity to remain in the organic phase when the pH of the aqueous phase was high and the organic to aqueous phase ratio was small. Extraction efficiency increased with the increasing lipophilicity of the crown ether carboxylic acids, which followed the order I < II < III. Using 2-(sym-dibenzo-16-crown-5-oxy)hexanoic acid as an extractant, lanthanides in some natural water and biological samples were determined by neutron activation analysis (NAA). Uranium can also be extracted by the three crown ether carboxylic acids with high efficiency. 2-(Sym-dibenzo-16-crown-5-oxy)hexanoic acid was utilized to extract uranyl ions from seawater and river water samples into chloroform, followed by back-extraction with a pH 2 nitric acid solution prior to NAA. The extraction method combined with NAA provides a sensitive method for the determination of uranium in natural waters.

• Research Organization: Idaho Univ., Moscow, ID (USA)
• OSTI ID: 5941926
• Country of Publication: United States
• Language: English

Related Subjects

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY
400101 -- Activation
Nuclear Reaction
Radiometric &amp; Radiochemical Procedures
400105* -- Separation Procedures
ACTINIDES
ACTIVATION ANALYSIS
ALCOHOLS
BIOLOGICAL MATERIALS
CARBOXYLIC ACIDS
CHEMICAL ANALYSIS
ELEMENTS
EXTRACTION
GLYCOLS
GROUND WATER
HYDROGEN COMPOUNDS
HYDROXY COMPOUNDS
MATERIALS
METALS
NEUTRON ACTIVATION ANALYSIS
ORGANIC ACIDS
ORGANIC COMPOUNDS
ORGANIC POLYMERS
OXYGEN COMPOUNDS
PH VALUE
POLYETHYLENE GLYCOLS
POLYMERS
RARE EARTHS
RIVERS
SEAWATER
SEPARATION PROCESSES
STREAMS
SURFACE WATERS
URANIUM
WATER