Groundwater and surface water contamination with nitrate and nitrite keeps increasing all around the world due to the excessive use of fertilizer. Without the proper treatment, these contaminants can induce the blue baby syndrome(methemoglobinemia) and cancer. Due to the harmful effect of these contaminants, the U.S. EPA has set the federal regulation on the maximum level of nitrate and nitrite in drinking water to be 10 mg-N/L and 1 mg-N/L , respectively. Catalytic treatment is a promising technology that can sustainably reduce nitrate and nitrite to nitrogen using hydrogen gas as an electron donor. However, current research on the catalytic reduction has a limitation because of the production of ammonia as a by-product. In this study, we have developed Hollow Carbon Sphere(HCS) supported Pd-based catalysts, which yields very low concentration of ammonia during nitrite reduction. Catalyst activity, selectivity, and longevity has been investigated and the catalyst structure and metal dispersion were also analyzed using microscopic and spectroscopic characterization. The role of HCS on the reaction pathway of reduction of nitrate to nitrogen over ammonia was further examined by evaluating the formation of intermediates such as NO and N2O as well as crystal structure of Pd and promotor metal catalysts. Findings from this study has a broader implication to improve the selectivity of catalysts and minimize the formation of undesired by-product during nitrate treatment.

Development of bimetallic Pd-based catalyst supported on the hollow carbon spheres for selective nitrate and nitrite reduction

2019 Spring National Meeting

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