Study on the removal performance of X-3B by CoFe₂O₄-loaded bentonite catalyzed peroxyacetic acid

A novel CoFe2O4-loaded bentonite catalyst, denoted as Bt-CoFe2O4, was synthesized based on the co-precipitation with bentonite, ferrous nitrate, and cobalt nitrate as the raw materials. It was employed to activate peroxyacetic acid (PAA) for the model dye degradation, reactive red (X-3B). Characterization and analysis of the catalyst were conducted using scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FT-IR), and X-ray photoelectron spectroscopy (XPS) to investigate its catalytic activity towards PAA. Furthermore, the impact of initial pH, PAA concentration, and other species present in the aqueous phase on the degradation efficiency of X-3B was meticulously examined. The experimental results demonstrated that under the conditions of 100 mg·L−1 of catalyst concentration, 0.3 mmol·L−1 PAA, and 100 mg·L−1 X-3B, X-3B was efficiently degraded by 96.4% within 8 minutes. Notably, the presence of chloride ions and humic acid significantly inhibited the degradation process of X-3B, whereas bicarbonate ions exerted a pronounced promotional effect. Quenching experiments combined with electron paramagnetic resonance (EPR) spectroscopy unambiguously identified the organic radical R−O· as the predominant reactive species involved in the degradation mechanism. Moreover, the catalyst exhibited excellent stability in consecutive reaction cycles, confirming its potential for practical applications.