Cycle 1 (2011 Deadline)
Investigation into persulfate/peroxymonosulfate oxidation of micro-contaminants towards water sustainability: mechanism, kenetics, and implementation
PI: Antoine Ghauch, American University of Beirut
US Partner: Richard Luthy, Stanford University
Project Dates: May 2012 - April 2015
Professor Antoine Ghauch presenting his PEER Science project results at the American Chemical Society meeting, New Orleans, April 2013.
Persulfate activation has attracted great interest within the scientific community as a way of producing short-lived sulfate radicals. These radicals are powerful oxidants that are more selective toward organic contaminants than the hydroxyl radicals that are often used for water and waste treatment. Using this approach, it may be possible to remove recalcitrant organic contaminants from water that are difficult to oxidize with existing treatment methods. The development of novel approaches for contaminant oxidation is critical to future efforts to secure water supplies in rapidly growing countries in arid climates. The issue of water quality is particularly important to Lebanon, where water shortages strike the Lebanese capital during August through November each year.
In this study, organic compounds that pose risks to human health and aquatic systems will be subjected to treatment with persulfate activated in various ways: thermally, photochemically (via sunlight) and chemically. This project will take several variables into account, such as ionic strength, sunlight intensity, concentrations of organic compounds, and chemical activators. Catalysts for persulfate activation will be developed using various metals and minerals, including some collected from Lebanese soils and waterways. These new chemical activators should be able to progressively activate persulfate and peroxymonosulfate into sulfate radicals in order to destroy organic micro-contaminants. This project should not only contribute to Lebanon's interests in educating its population but also help promote economic development, environmental protectoin, and capacity building among Lebanese researchers.
Summary of Recent Activities
In early 2013 the researchers on this project obtained new data on the removal of pharmaceutical compounds from water by thermal and chemical activation. Some of these results have been published or accepted for publication in peer-reviewed international journals. Dr. Ghauch’s site visit to the lab of his U.S. co-partner David Sedlak at the University of California, Berkeley in January 2013 proved very fruitful, as it helped launch experiments on the degradation of benzene using ferrihydrite as a persulfate activator and on the degradation of sulfamethoxazole using natural minerals of different fractional sizes. At the same time, the evaluation of an industrial iron-containing waste is in progress, and good results have been obtained on the degradation of ranitidine. The study team has established solid relations with USAID’s partner National Instruments, which reportedly will provide full technical support to the project. To this end, a meeting with the local NI representative in Lebanon took place at American University Beirut in March 2013. As for upcoming experiments, saturated carbonate solutions will be prepared and experiments will be run in sealed reactors to help understand the effect of the carbonate on persulfate activation and on iron dissolution into iron corrosion products.
Dr. Ghauch will present a poster on his research at the Micropol and Ecohazard conference in Zurich in June 2013, and he is scheduled to make another scientific visit to the United States in August 2013. In addition, graduate student Ghada Ayoub will spend two and one-half months at UC Berkeley this summer conducting research related to her findings in Lebanon.
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