Application of Flow Injection Analysis to Analyzing Precipitation/Coprecipitation Behavior of Chromium in Wastewater

A flow injection analysis based on spectrophotometry using diphenylcarbazide (FIA-DPC) was applied to the determination of Cr(VI) and total Cr (T-Cr) in order to understand the precipitation and coprecipitation behavior of Cr(III,VI) in wastewater. When 0.5 m of reaction coil, 100 μL of sample loop, and 1.2 mL/min of flow rate of carrier and reagent solutions were used, 10 μg/L 3 mg/L of Cr(VI) could be determined. The limits of detection and quantification were 1.1 and 3.6 μg/L, respectively. T-Cr could also be determined by combining pre-oxidation with permanganate. The precipitation/coprecipitation behavior of Cr(III,VI) obtained by using the FIA-DPC method was almost the same as the theoretical one, indicating that the method is applicable to analyze the behavior of Cr in wastewater.