UV enhanced denitrification using chlorine from seawater electrolysis for hydrogen production

Abstract

Seawater electrolysis is an attractive way to generate hydrogen energy. However, to commercialize this technology, it has been focused on developing chlorine-less oxygen generating electrodes for decades. Here, different from common ideas of minimizing chlorine formation at the anode, we aimed at reusing the waste chlorine from seawater electrolysis to mitigate nitrogen oxide (NOx) emissions. NOx removal performance of electrolyzed seawater containing chlorine was investigated under 254 nm ultraviolet (UV) irradiation in a semi-continuous bubbling reactor. Comparative parametric experiments were conducted for each factor with and without UV irradiation. Significant contributions of UV irradiation on denitrification performance of chlorine were observed under all investigated conditions. A ten-folder improvement in denitrification efficiency by the UV irradiated electrolyzed seawater was achieved under optimal conditions. Possible free radicals’ reaction mechanisms were discussed preliminarily. Results reveal that UV irradiated electrolyzed seawater is a promising way to reuse electrolyzed chlorine and mitigate acid gas emissions.