Rudenko A. Charge-selective composite membranes based on hydrated zirconium dioxide and bismuth oxynitrate for electrodialytic recovery of HCrO4- and F- ions from aqueous solutions.

Thesis for scientific degree of Candidate of Chemical Sciences in the speciality 2.04.00 “Physical Chemistry” (10.102 – Chemistry). – V.I. Institute of General and Inorganic Chemistry of the National Academy of Sciences of Ukraine, Kyiv, 2021. The thesis is devoted to the solution of an important scientific problem - to establish the influence of modifier based on hydrated zirconium dioxide and bismuth oxynitrate on the separation properties of composite membranes for electrodialytic recovery of ions from aqueous solutions. It was found that composite membranes containing a two-component modifier show charge selectivity and selectivity for HCrO4- and F- ions in comparison with the unmodified ceramic matrix and the membrane modified only with hydrated zirconium dioxide. It was found that composite membranes retain selectivity in a wide pH range. A method for modifying inert ceramic membranes by introducing composite particles into their macropores has been developed. The method involves the reinforcement of particles of the selective component (bismuth oxynitrate) with particles of the binder component (hydrated zirconium dioxide). The selectivity of composite membranes to F- ions is proved on the example of electrodialysis of combined solution containing an excess of Cl- ions. The membrane shows a current yield 78% for F-ions. As a result of electrodialytic separation of the solution simulating the chroming electrolyte, it was found that the composite membranes show a current yield of 71-97 % for HCrO4- ions. And with long-term removal of HCrO4- ions using composite membranes it is possible to achieve a recovery of 98%.