Reuse of PANI wastewater treated by anodic oxidation/electro-Fenton for the preparation of PANI

The present work investigated the treatment of the polyaniline (PANI) wastewater by anodic oxidation/electro-Fenton and reusing the treated PANI wastewater for the preparation of PANI. Organics were degraded by hydroxyl radical ( OH) and sulfate radical (SO 4 - ) formed simultaneously in the wastewater from electro-Fenton reaction and the anode surface. Under the conditions of 160 mL min −1 oxygen flow rate, constant current density 14 mA cm −2 and Fe 2+ concentration 0.2 mM, 89% COD can be removed from the PANI wastewater after 360 min treatment. The energy consumption was 50 kWh (kg COD) −1 and the current efficiency was 27.8%. After the PANI wastewater treatment , the aniline, aniline derivatives and aniline oligomers were removed from the wastewater. The PANI obtained using fresh solution, treated PANI wastewater and untreated PANI wastewater were recorded PANI-F, PANI-T and PANI-U, respectively. In the preparation of PANI-U, the reaction of p -benzoquinone with aniline or aniline oligomers could change the nucleation and growth, leading to the production of aggregated nanoparticles and low specific capacitance . However, the morphology and specific capacitance of PANI-T were similar to that of PANI-F. The PANI-T is three-dimensional sphere of nanofibers with high specific capacitance about 446.7 F g −1 . The yield of PANI-T using treated PANI wastewater could reach to 92.1%. These results demonstrate that the PANI wastewater treatment approach is efficient and environmentally friendly.