Low-cost chrysotile-supported Cu–Ce bimetallic catalyst for efficient peroxymonosulfate activation: singlet oxygen-driven dye degradation

Abstract

Dye wastewater containing methylene blue (MB) poses a serious threat to aquatic environments due to its persistence and biological toxicity. Advanced oxidation processes based on persulfate (PMS) activation can generate a variety of highly reactive oxidative species, representing a promising approach for wastewater treatment. In this study, a chrysotile-supported Cu–Ce bimetallic catalyst (Ser-CuCe-700) was prepared by the impregnation–calcination method and used to activate PMS to degrade MB. The results showed that the catalyst calcined at 700 °C exhibited excellent catalytic performance. Under optimal conditions (catalyst dosage = 300 mg L⁻¹, PMS concentration = 800 mg L⁻¹, initial MB concentration = 20 mg L⁻¹, temperature = 25 °C), an MB removal efficiency of 87.7% was achieved within 90 min. Moreover, the system demonstrated a broad adaptable pH range and good stability, maintaining high degradation performance over five consecutive cycles. Mechanistic investigations revealed that the reversible valence transitions of Cu (Cu²⁺/Cu⁺) and Ce (Ce⁴⁺/Ce³⁺) established an efficient electron-transfer pathway, thereby promoting PMS activation. Quenching experiments confirmed that ¹O₂ served as the dominant reactive species, while SO₄˙⁻ and ·OH contributed as secondary active species. This study highlights the potential of chrysotile as a low-cost natural support and provides an efficient and practical strategy for treating refractory dye wastewater.