NFe⁰/GAC-mediated advanced catalytic per-oxidation for pharmaceutical wastewater treatment

In the present study, the treatment of pharmaceutical wastewater (PWW) in terms of organic content (COD, TOC) has been investigated using advanced catalytic per-oxidation (ACPO) with granular activated carbon supported nano zero valent iron (nFe⁰/GAC). The characteristics of PWW and optimization of reaction parameters that influence the process efficiency have also been evaluated. The PWW contains a high amount of organic content of non-biodegradable nature. At optimum conditions, ∼81% COD and ∼76% TOC removal was attained. Moreover, ACPO process was more favorable to the complete oxidation. The reaction kinetics follows the two-step pseudo first-order model. The activation energy (E) for the first and second steps was calculated as ∼22 and ∼23 kJ/mol, respectively. The two-step kinetics can be attributed primarily to the oxidation of organic compound first to short chain molecular structures (organic acids) followed by their complete oxidation to produce carbon dioxide and water. Moreover, the average oxidation state (AOS) got raised from -1.8 to 2.1, which represents the strong mineralization and the generation of highly oxidized intermediates. Thus, the treatment of PWW using nFe⁰/GAC + H₂O₂ could be considered to be an effective alternative treatment option.