Solar CPC pilot plant photocatalytic degradation of bisphenol A in waters and wastewaters using suspended and supported-TiO₂. Influence of photogenerated species
2014
Saggioro, Enrico Mendes | Oliveira, Anabela Sousa | Pavesi, Thelma | Tototzintle, Margarita Jiménez | Maldonado, Manuel Ignacio | Correia, Fábio Verissimo | Moreira, Josino Costa
Photocatalytic degradation of bisphenol A (BPA) in waters and wastewaters in the presence of titanium dioxide (TiO₂) was performed under different conditions. Suspensions of the TiO₂ were used to compare the degradation efficiency of BPA (20 mg L⁻¹) in batch and compound parabolic collector (CPC) reactors. A TiO₂ catalyst supported on glass spheres was prepared (sol–gel method) and used in a CPC solar pilot plant for the photodegradation of BPA (100 μg L⁻¹). The influence of OH·, O₂ ·⁻, and h ⁺ on the BPA degradation were evaluated. The radicals OH· and O₂ ·⁻ were proved to be the main species involved on BPA photodegradation. Total organic carbon (TOC) and carboxylic acids were determined to evaluate the BPA mineralization during the photodegradation process. Some toxicological effects of BPA and its photoproducts on Eisenia andrei earthworms were evaluated. The results show that the optimal concentration of suspended TiO₂ to degrade BPA in batch or CPC reactors was 0.1 g L⁻¹. According to biological tests, the BPA LC₅₀ in 24 h for E. andrei was of 1.7 × 10⁻² mg cm⁻². The photocatalytic degradation of BPA mediated by TiO₂ supported on glass spheres suffered strong influence of the water matrix. On real municipal wastewater treatment plant (MWWTP) secondary effluent, 30 % of BPA remains in solution; nevertheless, the method has the enormous advantage since it eliminates the need of catalyst removal step, reducing the cost of treatment.
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