Enhanced peroxymonosulfate activation by a polydopamine-decorated CoMoO4 composite towards efficient decomposition of tetracycline hydrochloride in wastewater

Abstract

In this work, a novel polydopamine (PDA)-decorated CoMoO₄ (PDA@CoMoO₄) composite was fabricated and employed to catalyze peroxymonosulfate (PMS) towards tetracycline hydrochloride (TCH) decomposition from aqueous solutions. It was discovered that the PDA@CoMoO₄ exhibited excellent performance and enhanced TCH decomposition. The results revealed that the system with a catalyst dosage of 80 mg L⁻¹ and a PMS dosage of 1.0 mM could decompose 98.0% of 15 mg L⁻¹ TCH after 50 min. Electron paramagnetic resonance (EPR) analyses and reactive oxygen species (ROS) capture tests verified that multiple ROS, including singlet oxygen (¹O₂), superoxide anions (O₂˙⁻), sulfate radicals (SO₄˙⁻), and hydroxyl radicals (˙OH), were involved in TCH decomposition. A potential catalytic mechanism of PDA@CoMoO₄ catalyzed PMS was proposed, mainly involving the promotion of Mo⁶⁺/Mo⁴⁺ and Co³⁺/Co²⁺ redox cycles by electrons provided by PDA, and the synergistic effect of Mo⁶⁺/Mo⁴⁺ and Co³⁺/Co²⁺ redox cycles in catalyzing PMS. Following four consecutive cycles, the TCH elimination efficiency remained above 87%, suggesting that the PDA@CoMoO₄ composite has good reusability. In short, the PDA@CoMoO₄ composite is a good candidate material for wastewater treatment.