Spectrophotometric Determination of Fe(II)EDTA-NO, Fe(II)EDTA/Fe(III)EDTA in Chemical Absorption-Biological Reduction Integrated NOx Removal System

Abstract

Fe(II)EDTA-NO, Fe(II)EDTA and Fe(III)EDTA are three key chemical species in the chemical absorption-biological reduction (CABR) integrated NOx removal system. The original ferrozine method was modified to quickly determine Fe(II)EDTA/Fe(III)EDTA in small volumes of liquid samples. It is shown that the presence of EDTA do create differences in absorbance. The measurement of Fe(II)EDTA and total iron were performed on two separate sample fractions. A spectrophotometric method for direct determination of Fe(II)EDTA-NO was proposed. The results indicated that Fe(II)EDTA-NO could be accurately determined by spectrophotometry under optimized conditions: an absorption wavelength of 438 nm, pH between 5.23~8.07, and operating time under one minute. The final standard curve was given and the mathematic relations among them were also discussed.