Study of the intensification of solar photo-Fenton degradation of carbamazepine with ferrioxalate complexes and ultrasound

Highlights: • We have studied the mineralization of carbamazepine aqueous solutions. • 80% TOC removal from the treated water was reached. • A reaction pathway for the CBZ mineralization was proposed. - Abstract: The intensification of the solar photo-Fenton system with ferrioxalate photoactive complexes and ultrasound applied to the mineralization of 15 mg/L carbamazepine aqueous solution (CBZ) was evaluated. The experiments were carried out in a solar compound parabolic collector (CPC) pilot plant reactor coupled to an ultrasonic processor. The dynamic behavior of hydroxyl radicals generated under the different studied reaction systems was discussed. The initial concentrations of hydrogen peroxide and ferrous/oxalic acid and pH were found to be the most significant variables (32.79%, 25.98% and 26.04%, respectively). Under the selected optimal conditions ([H₂O₂]₀ = 150 mg/L; [Fe²⁺]₀ = 2.5 mg/L/[(COOH)₂]₀ = 12.1 mg/L; pH = 5) CBZ was fully degraded after 5 min and 80% of TOC was removed using a solar photo-Fenton system intensified with ferrioxalate (SPFF). However, no improvement in the mineralization using SPFF process combined with ultrasound was observed. More mild pH conditions could be used in the SPFF system if compared to the traditional photo-Fenton (pH 3) acidic systems. Finally, a possible reaction pathway for the mineralization of CBZ by the SPFF system was proposed and therein discussed.