<p>Graphene oxide (GO) loaded with magnetite (Fe₃O₄@GO) shows promise as a catalyst for advanced oxidation processes (AOPs). Fe₃O₄ generates free radicals by reacting with oxidants, while GO enhances the reaction. This study evaluated Fe₃O₄@GO with hydrogen peroxide (H₂O₂) and persulfate (S₂O₈²⁻) for acetaminophen (APAP) degradation and examined the formation of harmful haloacetamides (HAMs) during subsequent chlorination and analyzes the evolving surface characteristics of the catalyst. The Fe₃O₄@GO/H₂O₂ system achieved 49% APAP removal after 1&#xa0;h, primarily through adsorption onto Fe₃O₄@GO (23%) and direct oxidation by H₂O₂ (19%). It generated fewer radicals (^•OH and SO₄^•–), resulting in a reduced potential for HAM formation during subsequent chlorination. In contrast, the Fe₃O₄@GO/S₂O₈²⁻ system showed a synergistic effect, with APAP removal attributed to adsorption onto Fe₃O₄@GO (23%), direct oxidation by S₂O₈²⁻ (7%), and AOP mediated by the Fe₃O₄@GO/S₂O₈²⁻ system (76%). This system also exhibited efficient radical generation, resulting in an increased HAM formation potential. Although H₂O₂ can work as both an oxidant and a reductant, it appeared to act mainly as a reducing agent in the presence of Fe₃O₄@GO. This interaction weakened the oxygen-containing functional groups of GO and caused Fe loss, thereby reducing the catalytic performance of GO/S₂O₈²⁻. In contrast, S₂O₈²⁻ caused less structural damage to the catalyst, thereby enhancing its reusability. The Fe₃O₄@GO/S₂O₈²⁻ system maintained high APAP degradation efficiency over multiple reaction cycles, highlighting its potential for sustainable AOP applications.</p>