Abstract

Nitrate removal through electroreduction using stainless steel electrodes in recycle mode was found to be enhanced by addition of salts (NaCl, KCl, NaCl₂ and MgCl₂), acids (HCL, H₂SO₄; CH₃-COOH and H₃PO₄) or aluminosilicate-based catalysts (bentonite, kaolin, illite-montmorillonite mixture and clinoptilolite). High nitrate removal yields were obtained in the presence of salts under optimum flowrate. The ionic strength and current density induced by chlorinated salts appear to promote the electrochemical denitrification. This effect was stronger as compared to that produced by acid addition. Acid addition appears to mainly improve the ionic force. The flowrate effect was found to strongly correlate to those of all added species. These results open promising prospects for low-cost clay-catalyzed nitrate electroreduction under dynamic conditions.

Keywords: Nitrate; Clay minerals; Zeolites; Catalysts; Electroreduction