University of North Florida
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Stuart Chalk, Ph.D.
Department of Chemistry
University of North Florida
Phone: 1-904-620-1938
Fax: 1-904-620-3535
Website: @unf

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Classification: Commercial product -> battery -> Electrolyte

Citations 1

"Flow Injection Spectrophotometric Determination Of Nitrate In Electrolyte Of Lead-acid Batteries"
Talanta 1997 Volume 45, Issue 2 Pages 265-271
Fábio R. P. Rocha* and Joaquim A. Nóbrega

Abstract: Electrolytes of lead-acid batteries can contain several impurities that reduce battery performance and lifetime. Nitrate ions are among these species because they can be reduced to ammonium in the lead electrode. In this work, an analytical method was developed to determine this anion in electrolytes of batteries used in telephone systems, in which nitrate concentration must be lower than 10 mg L-1. The procedure consists in the reduction to nitrite in a copperized cadmium column followed by Griess's modified reaction. Due to the high sensitivity of this methodology, a large dispersion flow diagram (dispersion coefficient = 27.8) was projected. Thus, it was possible to eliminate the Schlieren effect and to obtain a NH3/NH+4 buffer in the sample zone in a suitable pH for reduction reaction (pH 8). Negative interference due to iron(III) was overcome by addition of excess iron (200 mg L-1). A relocatable filter was used to remove iron(III) hydroxide precipitate. This avoided adsorption on the surface of the filings and increase of back pressure. The analytical frequency is 80 measurements/h and the detection limit was estimated as 0.3 mg L-1 in a 99.7% confidence level. A 2.2% relative standard deviation was obtained in a repeatability study (n = 10) by using a 25 mg L-1 nitrate solution in a 3.6 mol L-1 sulfuric acid medium. Recoveries from 95.5 to 104% were obtained by spiking 5.00 or 10.0 mg L-1 of nitrate in samples of battery electrolyte.
Nitrate Spectrophotometry