11 research outputs found
Ultrasonic spectral analysis methodology for thickness mapping of electrochemical hydrogen meter thimbles
An ultrasonic spectral analysis based methodology has been developed and successfully implemented to measure wall thickness in the range of 0.3 to 0.7 mm in iron thimbles using low frequency ultrasonic waves (around 10 MHz). Conventional ultrasonic techniques cannot be used in such
cases because of the low thickness of the thimble and the presence of curvature. Using a low frequency (15 MHz) immersion transducer and low digitization (under 200 MHz), an accuracy of ±10 μm has been achieved. The importance of the window for selection of time domain data for spectral analysis has been clearly brought out. A software program has been developed for automated thickness measurement across a line scan and for displaying the surface plot of thickness variations using the developed methodology
Spacer Monomer in Polymer Chain Influencing Affinity of Ethylene Glycol Methacrylate Phosphate toward UO<sub>2</sub><sup>2+</sup> and Pu<sup>4+</sup> Ions
The
complexation behavior of ligating groups bearing ethylene glycol
methacrylate phosphate (EGMP) units spaced in the polymer chain was
studied to understand the coordination ability of segregated EGMP
toward UO<sub>2</sub><sup>2+</sup> and Pu<sup>4+</sup> ions. The EGMP
units in the polymer chain were copolymerized with a varying mol proportion
of spacer monomer <i>N</i>-isopropylacylamide (NIPA) and
methyl methacrylate (MMA) along with a cross-linker. These copolymer
gels were characterized by FTIR, SEM/EDS, and thermal analysis. It
was observed that the copolymer gels had homogeneity and concentration
of phosphate groups systematically decreased with an increase in mol
proportion of spacer monomer
units. The hydrophlicity of (EGMP-<i>co</i>-MMA) copolymer
gels decreased with an increase in mol proportion of MMA units whereas
hydrophilicty of EGMP-<i>co</i>-NIPA copolymer increased
with an increase in mol proportion of NIPA units in the copolymer
gels. It was observed that UO<sub>2</sub><sup>2+</sup> ions sorption
decreased with an increase in MMA units in the polymer chain at higher
HNO<sub>3</sub> conc. (3 mol L<sup>–1</sup>) but did not affect
Pu<sup>4+</sup> ions sorption. This seems to suggest that EGMP units
segregated sufficiently in the polymer chain by spacers exhibit a
remarkable selectivity toward Pu<sup>4+</sup> ions with respect to
UO<sub>2</sub><sup>2+</sup> ions at high HNO<sub>3</sub> conc. PuÂ(IV)
ions are known to have high affinity toward nitrate ions that help
in the formation of a stable complex at higher acidity with a lesser
number of coordination with phosphate groups. The experiments showed
that the lower affinity of polyÂ(EGMP-<i>co</i>-MMA) gel
toward UO<sub>2</sub><sup>2+</sup> ions was not due to dilution of
phosphate groups concentration in the copolymer gel but could be attributed
to the coordination requirement of UO<sub>2</sub><sup>2+</sup> ions
to form a stable complex at higher HNO<sub>3</sub> concentration.
The X-ray photoelectron spectroscopy (XPS) and time-resolved laser-induced
fluorescence spectroscopy (TRLFS) studies of polyÂ(EGMP) loaded with
UO<sub>2</sub><sup>2+</sup> ions from aqueous solution having pH 2
and 3 mol L<sup>–1</sup> HNO<sub>3</sub> indicated that (i)
1:2 and 1:4 (UO<sub>2</sub><sup>2+</sup>–EGMP) complexes are
formed at lower acidity and higher acidity, respectively, (ii) UO<sub>2</sub><sup>2+</sup> ion is coordinated with water molecules at pH
range in addition to the ion-exchange, and (iii) the complex formed
in pH range has higher stability with respect to that form at 3 mol
L<sup>–1</sup> conc. The higher hydrophilic polyÂ(EGMP-<i>co</i>-NIPA) gels at 25 °C exhibit higher UO<sub>2</sub><sup>2+</sup> uptake in 3 M HNO<sub>3</sub>, as phosphate units in
hydrophilic gel are mobile and could form stable complex involving
3–4 phosphoryl oxygen, which is not possible in collapsed state
due to hydophobicity of polymer net work above critical temperature.
However, there was no effect of hydrophilicty/hydrophobicity on the
UO<sub>2</sub><sup>2+</sup> ions sorption in the copolymer gels from
solutions having lower HNO<sub>3</sub> conc. due to a requirement
of lesser number of EGMP units to form a stable complex