Spectrophotometric determination of trace chromium(VI) in electroplating wastewater

The fading reaction of arsenazo Ⅲ with Cr 2O 2- 7 in the nitric acid was studied, and a new spectrophotometric method with high sensitivity for Cr(Ⅵ) determination was established. The molar absorptivity was 3.9×10 6 L/(mol·cm), the absorption maximum was at 525 nm, the linear rang was 0～ 4 μg/(25mL), and the detection limit was 6.6×10 -9 g/mL. The optimal reaction conditions such as maximal absorption wavelength, medium, reagent dosage, tempreture, time and standard curve were studied, and satisfactory results were obtained in the trace Cr(Ⅵ) determination of electroplating wastewater.