Open AccessZirconium speciation in lactate solutions and polyacrylate gels
Author(s) -
Rose Jérome,
Chauveteau Guy,
Tabary René,
Renard Michel,
Omari Aziz,
Toulhoat Hervé
Publication year - 2001
Publication title -
journal of synchrotron radiation
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.172
H-Index - 99
ISSN - 1600-5775
DOI - 10.1107/s0909049500014631
Subject(s) - zirconium , extended x ray absorption fine structure , acrylate , tetramer , xanes , polymer , aqueous solution , chemistry , materials science , inorganic chemistry , polymer chemistry , copolymer , absorption spectroscopy , organic chemistry , physics , quantum mechanics , spectroscopy , enzyme
Controlling gelation kinetics is an important objective for several applications (ceramic and thin film syntheses, reduction in permeability of porous rock, etc.). There is a growing interest in studying the gelation of polymers by zirconium, a crosslinker of lower toxicity than the chromium which is still commonly used. XAS at the Zr K‐edge was performed at the European Synchrotron Radiation Facility (ESRF) on the BM32 beamline. The fluorescence detection was used to carry out successful in situ speciation at concentrations as low as 36 ppm. The Zr speciation was determined both in ZrLa (where La stands for lactate) aqueous solutions and in gels of a terpolymer of acrylamide having 2% of zirconium reactive acrylate side groups and 2% of sulfonate groups introduced to prevent syneresis. XANES results show that Zr is always in a dodecahedral geometry. In ZrLa solutions, EXAFS results indicate that Zr species grow from a dimer Zr 2 (La) 6 to a tetramer (Zr 4 (La) x ) and then to larger polymers resulting from tetramer associations, as the Zr concentration decreases from 51840 ppm to 36ppm. In polymer gels, Zr species appear to be dimers at pH 6 while tetramers are found when gelation occurred at pH 7. Calculations taking into account multiple scattering effects as well as dynamic molecular calculation confirmed conclusions derived from conventional EXAFS analysis.