Abstract
The use of deuterium-tungsten lamps and spectrometers limits the miniaturization, low power consumption, and in-situ deployment of Chemical Oxygen Demand (COD) instruments. This study introduces COD sensor utilizing LED and PN tube to overcome these disadvantages. However, PN tubes detect light within 250–800 nm and output an electrical signal, causing nonlinear errors(E) between the LED-derived absorbance (ALED) and COD concentration.This study, through model analysis, reveals that the LED’s emission spectrum and the solution’s absorption spectrum significantly impact errors, and this has been validated experimentally. Additionally, during two-point calibration with deionized water and calibration solution, the measurement error is positive when the concentration of the test solution is lower than that of the calibration solution, and negative when it is higher. Thus, we proposed a calibration and compensation method to reduce errors.Moreover, we have developed a compact, low-cost COD sensor with a measurement error of less than 1.6 mg/L.
Published Version
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