CoO/ graphite activated sodium percarbonate: Enhanced interfacial adsorption facilitates efficient oxidative...

Herein, graphite-supported cobalt oxide material (CoO/Gr) was synthesized via supramolecular self-assembly. The as-prepared nanocomposite exhibits nanowires-like morphology featuring CoO nanoparticles uniformly dispersed in graphite matrix. This material can effectively activate sodium percarbonate (SPC), leading to the efficient removal of Acid Orange 7 (AO7) from simulated wastewater. The as-synthesized CoO/Gr plays a synergistic role of both physical adsorption and prominent catalytic capability. The removal efficiency of AO7 by CoO/Gr was investigated under various conditions, including catalyst dosage, SPC concentration, pH, substrate concentration, and the presence of various anions. The results demonstrated that a relatively low dosage of the reagent can achieve efficient removal of AO7 across a broad pH range (3-12). Moreover, humic acid (HA) and HPO₄^- significantly inhibited the removal efficiency, whereas minimal impact of other common anions (Cl^-, F^-, SO₄^2-, NO₃^-) on the removal efficiency was observed. DFT calculations revealed the CoO/Gr metal-π bond interaction within the CoO/Gr structure, which significantly enhanced electron transport efficiency. Radical scavenging results and ESR spectroscopy showed that ·OH, CO₃^·-, O₂^·-, and ¹O₂ all participated in the degradation process. More specifically, CO₃^·- and O₂^·- played a dominant role in the catalysis process. The degradation pathway of AO7 and a plausible degradation mechanism were proposed based on the above results. Besides, the application of this obtained material in real wastewater was also estimated, nearly 80 % chemical oxygen demand (COD) removal can be observed within 120 min. We anticipate that this finding can provide a reference for addressing the bottleneck problems existing in the Fenton reaction.