Experimental investigation of optical properties of oily sewage with different pH environment

Optical properties of oily sewage play an important role in detection of water quality index of oily sewage. The transmittance spectra of oily sewage were investigated and the optical properties of oily sewage were calculated. Transmittance spectra were measured by a TU-1900 spectrophotometer in the range of 190˜900nm in pH of 6.5˜11.8. The oily sewage optical properties were calculated by the double thickness method, and the optical properties of oily sewage with different pH were compared. The results show that the transmittance of different optical path all decreased with the increase of pH in the range of 8.7˜11.8, and the transmittance in acidic environment is much higher than that in alkaline. In the wavelength of 240˜350 nm and 650˜850 nm, the pH has obvious influence on the refractive index. With the increase of pH in range of 8.7˜11.8, the absorption index has a significant downward trend. When pH is 9.6 and wavelength range is 300˜700nm, the effect of pH change on the refractive index is greater than that of the absorption index.When the solution is neutral, the fitting of the optical properties of oily sewage is the best.