Magnetic Co-Co Prussian blue analogue catalyst for peroxymonosulfate activation to degrade organic dye

Abstract

• Magnetic Fe 3 O 4 /Co 3 [Co(CN) 6 ] 2 can efficiently activate peroxymonosulfate. • Synergistic catalysis between Fe 3 O 4 and Co 3 [Co(CN) 6 ] 2 enhanced the degradation of RhB. • SO 4 − and OH played important roles in the degradation process of RhB. • Synergistic catalytic mechanism was proposed. • Magnetic properties of Fe 3 O 4 /Co 3 [Co(CN) 6 ] 2 facilitated the recovery of the catalyst. In this study, the Fe 3 O 4 /Co 3 [Co(CN) 6 ] 2 composite catalyst was synthesized by co-precipitation method. The morphology and the structure of Fe 3 O 4 /Co 3 [Co(CN) 6 ] 2 composites were characterized by XRD, FTIR, SEM, TEM, EDS, XPS, VSM. The results showed that the removal rate of RhB (10 mg/L) reached 99.5% in 40 min in the 0.4-Fe 3 O 4 /Co 3 [Co(CN) 6 ] 2 (200 mg/L) + PMS (50 mg/L) system with a pseudo first-order degradation rate constant (k) of 0.121 min −1 , which is nearly 2.16 times of that (0.0561 min −1 ) in the Co 3 [Co(CN) 6 ] 2 + PMS system and 18.9 times of that (0.0064 min −1 ) in the Fe 3 O 4 + PMS system. The observed synergistic catalysis between Fe 3 O 4 and Co 3 [Co(CN) 6 ] 2 in Fe 3 O 4 /Co 3 [Co(CN) 6 ] 2 enhanced the degradation of RhB. The electron paramagnetic resonance (EPR) analysis and quenching experiment indicated that SO 4 − and OH played important roles in the degradation process of RhB. A synergistic catalytic mechanism of PMS activation by Fe 3 O 4 /Co 3 [Co(CN) 6 ] 2 , which mainly involves the enhanced Co 2+ /Co 3+ cycle by Fe 2+ donated electrons, was proposed. In summary, owing to its easy preparation, excellent catalytic activity, and reusability, the Fe 3 O 4 /Co 3 [Co(CN) 6 ] 2 composite catalyst is a good candidate for remediation of contaminated water.