Insight into the Role of Defect CN Layer in Enhanced Catalysis of Peroxymonosulfate on Magnetic Cobalt Carbocatalyst for Phenol Degradation

Phenolic wastewaters possess high toxicity and poor biodegradation and persist in ecosystem for longer periods, causing severe harm to living organisms. Thus, developing highly effective catalysis-oxidation system for phenolic wastewater treatment is highly needed. In this work, a high-performance magnetic cobalt carbocatalyst (M-Co/CN) was prepared via thermal pyrolysis of the amorphous cobalt-aspartic acid complex. It was further applied for activation of peroxymonosulfate (PMS) to degrade phenolic wastewaters. Related characterization results revealed that the compositions, structures, properties of the catalyst mainly depended on pyrolysis temperature. The formed porous CN layer at 600 degrees C could enhance adsorption and catalysis through improving mass transfer, restricting Co aggregation, and exposing more active sites. Therefore, the catalyst we prepared could show high catalytic performance in process of phenol wastewater treatment. Besides, reaction conditions (catalyst dosage, PMS dosage, phenol concentration, pH, and anion type, etc.) were further studied and optimized. Under the optimized conditions, a degradation efficiency of 95.0% was achieved for 100 ppm phenol within 1 h. Furthermore, radical quenching experiments and electron paramagnetic resonance spectroscopy jointly displayed that phenol degradation mechanism in the M-Co/CN-600-PMS system primarily involves the generation of singlet oxygen (1O2) with Co0 serving as active reaction sites. Besides, recycling experiment also demonstrated that M-Co/CN catalyst had high structure stability and better reusability after tests.