PRODUCTION OF HIGHLY DISPERSED AMORPHOUS SIO₂ FROM INDUSTRIAL ALKALINE SOLUTIONS USED IN THE REGENERATION OF ION-EXCHANGE RESINS

Abstract

The possibility of obtaining precipitated silicon dioxide from industrial alkaline silicate solutions, formed during the regeneration of ion-exchange resins contaminated with silicon compounds in uranium hydrometallurgy, has been investigated. SiO₂ precipitation was carried out using sulphuric acid, with the effects of precipitant concentration, temperature, process duration, pH of the medium and drying temperature evaluated. It was established that the optimal conditions for obtaining the precipitate are: a 40% H₂SO₄ solution, a precipitation temperature of 25 °C, a process duration of 2 hours, pH 6–8 and subsequent drying at 300 °C. Under these conditions, an amorphous, highly dispersed silicon dioxide was obtained with a SiO₂ content of up to 86.7% and a specific surface area of up to 357 m²/g. Based on low-temperature nitrogen adsorption data and BET, BJH and NLDFT calculations, the formation of a highly developed micro-mesoporous structure was confirmed. The results obtained demonstrate the potential for processing alkaline silicate solutions from the regeneration of ion-exchange resins to produce a functional silica material and reduce the volume of industrial waste.