Homogeneous Photosensitized Oxidation for Water Reuse in Cellars: A Study of Different Photosensitizers.

The demand for fresh water is increasing daily, requiring industries to take action to reduce the need for fresh water. Winemaking industries represent a massive hydric impact by combining the water consumed and the high volume of wastewater produced. The sun-driven photooxidation process has been widely employed in removing wastewater pollutants. This work employed four photosensitizers, Rose Bengal, AlPcS₄, ZnPcS₄, and TPP, for water reuse in cellars. A secondary effluent has been investigated as a water matrix. Of all the photosensitizers (PS) employed, ZnPcS₄ showed better chemical oxygen demand (COD) (23%) and phenolic (TPh) (81%) removal. The effect of pH and concentration was also assessed for ZnPcS₄. The phenolic content removal was found to be highly dependent on the solution's pH, as alkaline solutions improve the singlet oxygen quantum yield where the use of a pH = 11 reached 42% and 81% of COD and TPH removal. However, a pH higher than 7 showed higher PS bleaching than pH = 7. Three different PS concentrations were evaluated: 3 × 10⁻⁶, 5 × 10⁻⁶, and 1 × 10⁻⁵ mol/L. The optimal PS concentration was found to be 5 × 10⁻⁶ mol/L. [ABSTRACT FROM AUTHOR]