New sol–gel processes in the synthesis of inorganic sorbents and ion exchangers based on nanoporous oxides and phosphates of polyvalent metals

Abstract

The original competing-templating sol–gel method was proposed based on the idea that the formation of inorganic sols and gels always slower process than the formation of the corresponding precipitations; slowing down of solid phase formation (sol particles) can be realized by the competition with main reagents of the cations and anions added to one of starting precursors. This new sol–gel process can be conducted with water solutions only simplest salts, alkalis and acids without using chelating reagents. The date are also presented on the “oil-drop” and “air-drop” semi plant technologies for continuous sol–gel production of porous spherically granulated sorbents and inorganic ion exchangers such as amorphous titanium and zirconium phosphates. Here are represented also data about their porous structure and the role competing-templating triply charged cations (Al³⁺, Fe³⁺) in the ultra pores formation for selective sorption of heavy metals, radionuclides and uranium.