Abstract:  Caffeine (CAF), as an emerging contaminant, has been widely detected in various environmental media. Its environmental persistence and potential ecological risks pose a threat to aquatic environmental safety, making the development of an efficient CAF removal technology crucial for ensuring water security. This study developed a novel environmentally friendly solvent-free method to synthesize three-dimensional porous CuFe2O4-P catalyst. Experiments on CAF degradation were conducted using the CuFe2O4-P catalyzed peroxymonosulfate (PMS) system. Electron spin resonance (ESR) analysis, radical quenching experiments, X-ray photoelectron spectroscopy (XPS) characterization, and water quality factor impact experiments were comprehensively utilized to systematically investigate the degradation efficiency, underlying mechanism, and the influence of water quality factors on CAF degradation in this system. The results Showed that  the CuFe2O4-P/PMS system exhibited excellent catalytic activity, it could  completely degrade CAF (100% removal within 180 s) under optimized conditions (pH=7, PMS concentration=18 mg/L, catalyst dosage=0.3 g/L). In the CuFe2O4-P/PMS process, hydroxyl radicals (·OH) and sulfate radicals (SO4·-) contributed 66% and 34%, respectively, to the degradation of CAF. The presence of Fe(Ⅲ)/Fe(Ⅱ) and Cu(Ⅱ)/Cu(Ⅰ) redox cycles on the catalyst surface played a crucial role in enhancing SO4·- generation, thereby significantly improving CAF degradation efficiency. Carbonate (CO32-) and humic acid (HA) significantly inhibited the degradation process, reducing CAF removal to 8% and 20%, respectively, while nitrate (NO3-) had negligible effects. Notably, the system still achieved a 40% removal efficiency for CAF in real wastewater treatment plant effluent, highlighting its potential for practical applications.

Key words:  , three-dimensional porous catalyst, peroxymonosulfate, caffeine, reactive species, influencing factors