A monitoring method for sulfate based on ultraviolet absorption spectroscopy dedicated to SO3 monitoring in coal-fired power plants

[Display omitted] •The full spectrum measurement of sulfate ultraviolet absorption was studied.•A sulfate monitoring method with the lowest detection limit as low as 9 × 10-5 mol/L was designed.•A new SO3 measurement method achievable at a concentration level of 0.17 ppm was proposed. For understanding the SO3 emission level in coal-fired power plants to indicate the operating status of the SCR, a sulfate monitoring method based on ultraviolet absorption spectroscopy was proposed to feedback SO3 concentration. By measuring the absorption spectrum of sulfate, the red shift of the absorption peak was observed when the concentration was higher than 0.01 mol/L. Through optimization, a spectral range for sensitive detection of sulfate was obtained. A quadratic function was given for fitting the relationship between sulfate concentration and ultraviolet absorption. The minimum detection limit of sulfate was determined to be 9 × 10-5 mol/L.