tailieunhanh - Cyclic voltammetry study on the reduction of nitrate and nitrite on a copper electrode

The cathodic reduction of nitrate and nitrite ions on a copper electrode in aqueous potassium chloride solutions was studied using cyclic voltammetry technique. The cyclic voltammograms showed that nitrate and nitrite ion reduction occurred in the M KCl solution with peak potentials of to V and to V (Ag/AgCl) respectively. | Journal of Chemistry Vol. 45 2 P. 213 - 218 2007 CYCLIC VOLTAMMETRY STUDY ON THE REDUCTION OF NITRATE AND NITRITE ON A COPPER ELECTRODE Received 5 April 2006 NGUYEN VIET THINH1 2 NGUYEN THI PHUONG THOA2 LE QUOC HUNG3 Tiengiang University 2University of Natural Sciences Vietnam National University - Ho Chi Minh City institute of Chemistry Vietnam Academy of Science and Technology SUMMARY The cathodic reduction of nitrate and nitrite ions on a copper electrode in aqueous potassium chloride solutions was studied using cyclic voltammetry technique. The cyclic voltammograms showed that nitrate and nitrite ion reduction occurred in the M KCl solution with peak potentials of to V and to V Ag AgCl respectively. It was suggested from the data analysis that in the potassium chloride solution the reduction of nitrate and nitrite ions is irreversible. A minimal effect of pH on the reduction rate of nitrate and nitrite ions was found for the acidic and neutral solutions but it increased in the alkaline solutions. I - INTRODUCTION The nitrate contamination is one of the major water quality problems today. The uptake of nitrate in the human body causes oxygendeficiency such as cyanosis and breathing problems. Such toxicity is not due to nitrate itself but to nitrite formed from it. Nitrate is converted to nitrite by microorganisms present in the upper gastrointestinal tract and then nitrite adsorbed into the bloodstream reacts with hemoglobin to form methemoglobin. Methemoglobin formation prevents blood from carrying oxygen 1 . Furthermore nitrite impacts negatively on the body involve its reaction with secondary amines and amides to form N-nitroso amines and N-nitroso amides. These products are well-known precursors to cancer causing agents 2 . In 1985 the World Health Organization reported that nitrate concentrations in surface waters had increased extensively over the previous 30 - 40 years in many countries due to increasing use of artificial .