Monolayer characterization of several short alkyl chain phosphoric acid extractants

Journal Article · Wed Dec 01 00:00:00 EST 1982 · J. Colloid Interface Sci.; (United States)

DOI:https://doi.org/10.1016/0021-9797(82)90306-X· OSTI ID:5237524

Uphaus, R A; Vandegrift, G F; Horwitz, E P

The monolayer behavior of a group of short-chain alkyl phosphates was investigated with Langmuir trough techniques. The compounds were all octyl or ethylhexyl phosphates or phosphinates; the exceptionally small hydrophobic moieties in these compounds do not permit the formation of stable, coherent films at room temperatures. Stable monolayers were formed, however, on subphases of 1 M nitric acid at 5 to 10/sup 0/C. The apparent areas per molecule are consequently strongly temperature dependent with total desorption evidently taking place at room temperature. When compared to molecular areas estimated from space-filling models, the experimentally determined limiting molecular areas are greater by factors of 1.1 to 2. Compounds containing ethylhexyl groups yielded limiting molecular areas in much closer agreement with model estimates than did the octyl-containing compounds. A limiting minimal area per molecule, particularly for the ethylhexyl systems, was approached only after several cycles of compression and reexpansion. This result indicates that the weak van der Waals interactions present and the high viscosity of the systems allow coherent film formation only after repeated partial structuring of the system after several compressions. Expansion of previously compressed monolayers revealed marked hysteresis effects. The systems investigated included: di-n-octyl phosphoric acid, di-n-octyl phosphinic acid, tri-n-octyl phosphate, tri-n-octyl phosphine oxide, bis-2,2 dimethylhexyl phosphoric acid, bis (2-ethylhexyl) phosphoric acid, bis (2-ethylhexyl) phosphinic acid, 2-ethylhexyl, 2-ethylhexyl phosphonic acid, and tris (2-ethylhexyl) phosphate. 6 figures, 4 tables.

• Research Organization: Argonne National Lab., IL
• OSTI ID: 5237524
• Journal Information: J. Colloid Interface Sci.; (United States), Vol. 90:2
• Country of Publication: United States
• Language: English

Related Subjects

37 INORGANIC
ORGANIC
PHYSICAL AND ANALYTICAL CHEMISTRY
HDEHP
COMPRESSION
EXPANSION
NITRIC ACID
SORPTIVE PROPERTIES
TOPO
AQUEOUS SOLUTIONS
BENZENE
COMPARATIVE EVALUATIONS
EXPERIMENTAL DATA
FILMS
HYSTERESIS
ISOTHERM
MATHEMATICAL MODELS
MEDIUM TEMPERATURE
NUMERICAL ANALYSIS
SAMPLE PREPARATION
SURFACE AREA
TEMPERATURE DEPENDENCE
VAN DER WAALS FORCES
VISCOSITY
AROMATICS
DATA
DISPERSIONS
ESTERS
HYDROCARBONS
HYDROGEN COMPOUNDS
INFORMATION
INORGANIC ACIDS
MATHEMATICS
MIXTURES
NUMERICAL DATA
ORGANIC COMPOUNDS
ORGANIC PHOSPHORUS COMPOUNDS
PHOSPHORIC ACID ESTERS
SOLUTIONS
SURFACE PROPERTIES
400301* - Organic Chemistry- Chemical & Physicochemical Properties- (-1987)
400105 - Separation Procedures