Coupling of Heterogeneous Photocatalysis Process with Solar Photo Electro-Fenton Process to Improve the Mineralization of Salicylic Acid in a Solar 3L Flow Plant

Degradation of salicylic acid was performed coupling of the advanced oxidation processes:  solar photo electro Fenton Solar (SPEF) and solar photocatalysis (SPC) using TiO₂supported on glass spheres in a 3L flow plant.

Glass spheres (5mm in diameter) were covered with TiO₂synthesized by the sol-gel route from titanium butoxide as precursor using the dip-coating method. Deposits were obtained layer by layer until obtain 10 layers of catalyst. The amount of photocatalyst on the glass beads that was used for the experiments was 0.25 g/L.

Degradation of salicylic acid (165 mg/L) was carried out in a 0.05M Na₂SO₄ solution with pH adjusted to 3 and adding 0.5 mM Fe²⁺ as Fenton reagent. The current density applied was 50 mA/cm². The electrolytic cell consisted of Pt anode and an oxygen diffusion electrode as cathode.

 It was performed the processes of SPC, anodic oxidation with platinum (AO), AO-SPC, electro-Fenton (EF), SPEF and SPEF-SPC to evaluate the degradation and mineralization of salicylic acid. The obtained results during the mineralization for these processes were 9, 16, 27, 29, 59 and 66%, respectively. Also a study was conducted by varying the applied current density (50, 100 and 150mA/cm2) for the process of SPEF and SPEF-SPC, the result mineralization for each current intensity  was  59, 67, 78% for FEFS and 66, 76, 87% for FEFS-FC process .

The use of photocatalytic process with electrochemical processes to improve the mineralization of salicylic acid between 7-9% and this reduces energy costs and mineralization current efficiency.