Degradation of Naproxen Through the Synthesis of CoFe₂O₄ Loaded on Carbon Nanotubes: Effects of Parameters, Product Analysis, and Toxicity Study

Abstract

Background: Naproxen (NPX) is an emerging pharmaceutical contaminant in aquatic environments. Persulfate (PS)-based advanced oxidation processes show promise for degrading persistent pharmaceutical pollutants, and cobalt ferrite (CoFe2O4; CF) and multi-walled carbon nanotubes (MWCNTs) are effective materials for activating PS. Objectives: This study aimed to synthesize and characterize the MWCCF catalyst and evaluate its performance in NPX degradation via PS activation. Methods: CF nanoparticles were coated onto MWC using the co-precipitation method. The synthesized catalyst was characterized, and the effects of operational parameters on NPX degradation were investigated. The activation energy was determined by evaluating the effect of temperature, and the catalyst stability was assessed over repeated reaction cycles. Scavenger experiments were conducted using tert-butyl alcohol (TBA), methanol (MeOH), benzoquinone (BQ), and furfuryl alcohol (FFA) to elucidate the reactive species involved in NPX degradation. Degradation products were identified using dispersive liquid–liquid microextraction (DLLME) coupled with gas chromatography–mass spectrometry (GC-MS), and the toxicity of the treated solution was evaluated based on mung bean root growth. Results: Complete NPX degradation was achieved at pH 7, with a catalyst dose of 0.25 g/L, an NPX concentration of 10 mg/L, and a reaction time of 40 min. The activation energy of the MWCCF/PS process was 32.56 kJ/mol. The catalyst maintained an efficiency of > 98% over four consecutive reaction cycles. Scavenger experiments indicated the involvement of •OH, SO4•-, O2•-, and 1O2 in the catalytic process. GC-MS analysis identified low-molecular-weight products, including phthalic acid, benzeneacetic acid, and 1,3-dimethylbenzene. The treated NPX solution exhibited lower toxicity, as indicated by mung bean root growth. Conclusions: The MWCCF/PS process demonstrated high efficiency and good stability for NPX degradation. Multiple reactive species were involved, lower-molecular-weight degradation products were generated, and the toxicity of the treated solution was reduced.