Sol-gel materials for strontium(II) separation

In this study the sol-gel process was used to yield SiO₂ materials containing organic functional groups for the extraction of strontium(II) from waste streams. Previous techniques developed for removing strontium(II) from aqueous streams were focused on solvent extraction methods. The extraction technique proposed herein utilizes inorganic polymers containing organic ligating agents to remove strontium(II) from the waste stream. By using a solid phase extraction sorbent, organic waste is minimized during the extraction process. The efficiency of strontium(II) extraction by the developed materials was investigated. It was found that strontium ions could be absorbed into the sol-gel materials and then stripped from the materials, thus regenerating the sorbents for use in subsequent metal extraction cycles. Mixed oxide materials composed of ZrO₂ and SiO₂ were also developed via a sol-gel process, and were stable in alkaline media. The mixed oxide materials were used to extract strontium(II) from a waste system containing 1.0 M NaOH.