Aluminosilicate-catalyzed electrochemical removal of ammonium cation from water -kinetics and selectivity.

Aluminosilicate-catalyzed electrochemical decomposition of ammonium cation (NH4+) in water was investigated using NH4+-saturated clinoptilolite and copper-nickel electrodes in the presence of different salts and acidic species. The results showed beneficial roles of chloride anion and moderately acidic media. NH4+ adsorbed by the zeolites was converted with a 98% selectivity into nitrogen. The process was found to obey zero-order kinetics in the presence of clinoptilolite and a first order process when NaCl is added. Beneficial buffering effects of the zeolite and acidic species were registered. Clinoptilolite turned out to act as both catalyst and NH4+ reservoir. These results allow envisaging effective and waste-free technology in treating NH4+-rich aqueous effluents through total electroconversion into nitrogen using low cost aluminosilicates. Clay minerals, soils, sludges and natural water turbidity are potential catalysts for this purpose.