Activation of persulfate by magnetic granular activated carbon for tetracycline removal: performance, mechanism insight, and applications

In this study, magnetic granular activated carbon (MGAC) system based on persulfate (PS) for organic pollutant removal and its regeneration performance were comprehensively evaluated. Iron was successfully loaded onto the granular activated carbon (GAC) in the form of Fe₃O₄ through XRD patterns and SEM images. GAC and MGAC could activate PS for degrading tetracycline (TC). Compared with GAC, the adsorption and degradation of TC was significantly increased by 28% using MGAC. The optimized removal conditions were obtained: MGAC dosage of 1.5 g/L, PS concentration of 10 mM, and pH of 4.6. TC could be removed in a relatively wide pH from 3~9 using MGAC/PS system. The degradation mechanism was mainly ascribed to SO₄•-, O₂•-, and •OH radicals, according to the results of radical scavengers’ studies. Moreover, MGAC had good recycling and reusability through peroxymonosulfate regeneration. Finally, a fixed bed reactor using MGAC was carried out to simulate practical application. This work not only provided insight into the antibiotics degradation using MGAC but also laid a foundation for the practical application of this composite.