Новые решения в технологии получения ферратов(VI) с использованием модифицированных SnО₂-электродов

Abstract

Изучены особенности образования ферратов(VI) из соединений Fe(III) в растворах с различным ионным составом на инертных SnО₂-электродах, легированных Ru, Pt, Pd и Sb. Установлено, что изменением природы и содержания легирующего металла можно целенаправленно регулировать электро-каталитические свойства анодов, в частности величину перенапряжения выделения О₂. Показана принципиальная возможность электрохимического окисления на поверхности электрода и химического окисления в объеме раствора частиц Fe(ОН)₃ и Fe(ОН)₄. Разработаны рекомендации для синтеза ферратов(VI) с использованием анодов, обеспечивающих длительный режим работы без ухудшения их эксплуатационных характеристик.

Disadvantages of traditional synthesis methods of ferrates (VI) - promising green oxidants - stimulate the search of new technological solutions which meet the requirements of modern production. The purpose of this work was to study the ferrates (VI) formation from Fe (III) compounds in solutions with different pH on inert SnО₂ electrodes doped with Pt, Ru, Pd, and Sb. The influence of the nature and the content of the alloying metal on the electrocatalytic properties of the electrode was studied by the stationary voltammetry method, as well as by determining the current yields of hypochlorite and sodium chlorate during the electrolysis of a slightly alkaline NaCl solution. Coatings based on SnО₂, doped with palladium and platinum, show maximal electrocatalytic activity according to ClO – synthesis. It has been established that the oxygen evolution overvoltage on the electrodes with comparable dopant concentrations increases in the Ru-Pd-Pt-Sb series. It has been shown that for effective synthesis of ferrates (VI), flat Ti anodes of a large area with an electroactive layer based on SnО₂-Sb2О₃ should be used. It is noted that electrochemical oxidation of Fe (III) in Fe (VI) is more energetically favorable on these electrodes than О₂ evolution, which opens up new possibilities for these processes in ferrate (VI) synthesis technology. We have shown the principal possibility of increasing the productivity of the Fe (VI) process due to the direct interaction of the Fe(ОН)₃ and Fe(ОН)₄− particles in the solution volume with ClO− anions generated on an inert electrode when Сl− anions are preliminarily added to the system. Technological solutions have been proposed to increase the life of inert electrodes when 5-10% TiO2 is introduced into the SnО₂ matrix, providing a long-term operating mode without degradation of their performance characteristics.