Developing an effective and efficient process for removing phosphate from water has a twofold benefit for society: prevention of eutrophication in waterways and development of a sustainable source of phosphorus-based fertilizers for food production. Various types of adsorbents have been shown to address this issue. However, many of these materials do not allow subsequent release of captured ions and exhibit low recyclability.  Past studies have demonstrated the ability of zeolites to capture ions in aqueous media. By exchanging copper ions into the framework of ZSM-5, we have been able to selectively remove free phosphate ions in aqueous media with a maximum uptake of 332 mg-P/g. Regenerating the Cu-ZSM-5 in a concentrated brine solution released over 80% of the captured phosphate from the zeolites. We found that Cu-ZSM-5 demonstrated considerable recyclability and only lost activity due to the leaching of copper ions.<br/>We performed systemic studies involving ICP-MS and XPS to confirm Cu(II) as the active site for capture. The data was fit to several isotherms to elucidate the capture and release mechanism.  The future of this project involves extending the chemical principles to other types of zeolites and metals cations. We have performed identical capture and regeneration experiments with the protocol described but substituting the copper ion with other metal. As well as varying the substituted cation, we are also varying the zeolite framework that the ion is attached to with other zeolite geometries.

Phosphate sequestration via copper-exchanged ZSM-5

254th National Meeting (2017)

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