Optimization of Heterogeneous Photosensitized Oxidation for Winery Effluent Treatment

Abstract

In this study, the heterogeneous photosensitized oxidation treatment of winery effluents was optimized using chitosan carriers immobilized with Zn(II) Phthalocyanine tetrasulfonic acid. The influence of main operating parameters such as initial pH, aeration flow rate, photocatalyst load, and concentration of the photosensitizer used in the photocatalysts’ preparation was investigated. Results for chemical oxygen demand (COD) and phenolic content (TPh) removals are presented for each of the tests performed. Best reductions were obtained after 30 min of treatment in natural sunlight at an initial pH of 4.0 and an aeration flow of 2.8 L/min since it allowed reductions of 45% for COD and 73% for phenolic content (TPh). In addition, the possibility of reusing the photocatalysts during several cycles was also assessed, where an acidic initial pH allowed their reuse, being the only pH value studied where the leaching of the photosensitizer was not observed. In these conditions, the same photocatalysts were reused for six reaction cycles, and efficiency started to decrease after the third use. Thus, a greater mass and concentration of photosensitizer contributed to a superior reduction in organic matter. The results show that heterogeneous photosensitized oxidation using sunlight radiation as an energy source is an interesting approach for obtaining reusable water from winery effluents.