Turbidity compensation method based on Mie scattering theory for water chemical oxygen demand determination by UV-Vis spectrometry

The COD standardsolutions (5,10,15,20,25,30,35,40,45,50mg/L) and turbidity standard solutions (10,20,30,40,50NTU) were prepared in the laboratory. UV2550 spectrophotometer was used to measure absorption spectra of COD, turbidity solutions, and their mixed solutions in the wavelength range of 220–700nm. Turbidity compensation models based on Mie scattering theory for different solutions were established by Matlab Software. On this basis, the COD prediction model of mixed solutions before and after turbidity compensation was established by Matlab software again, and the results of predcited turbidity were compared with other turbidity compensation methods (350nm PC, dervative method, improved MSC). Moreover, 5 different water samples were collected from Swan Lake Park (Hefei, China) in 2020 to verify the effectiveness of the method.