Degradation of paracetamol in a bubble column reactor with ozone generated in electrolyte-free water using a solid polymer electrolyte filter-press electrochemical reactor

摘要

A porous anode composed of β -PbO~(2)was electrochemically deposited onto a carbon cloth substrate (e.g., CC/ β -PbO~(2)) aiming for the electrochemical ozone production (EOP) in electrolyte-free water using a solid polymer electrolyte (SPE) filter-press reactor. Scanning electron microscopy (SEM) images revealed the presence of a three-dimensional oxide structure necessary to obtain a fluid-permeable anode. X-ray analysis showed the predominance of the β -PbO~(2)phase. The maximum current efficiency for the EOP was 9.5% with an ozone production rate of 1.40?g?h_(?1). Using a constant ozone production rate of 0.5?g?h_(?1), the oxidative degradation of paracetamol (PCT) dissolved in water was accomplished as a function of the PCT concentration (20, 30, and 50?mg?L_(?1)) and the pH (acid, natural (without adjustment), and alkaline). The UV-Vis spectrophotometric analysis showed that the degradation process is more pronounced in alkaline media with a strong reduction in the electrical energy per order ( E ~(EO)). A reduction of the chemical oxygen demand (COD) of up to 80% was observed. A linear correlation between data referring to COD and HPLC measurements with the UV absorbance measured at 243?nm (UV~(243)) was verified indicating that these different techniques can be complementary to each other. The nuclear magnetic resonance (NMR) study of the ozonation by-products revealed that the oxidation of PCT occurred through the rupture of the aromatic ring. The major part of phenol’s ring was oxidized to CO~(3)_(2?)while no reaction occurs in the acetamide group of paracetamol during the ozonation reaction.