Aqueous Atrazine Photocatalytic Degradation over g-C3N4/graphene/NiFe2O4 Nanocomposite in the Presence of Potassium Peroxymonosulfate

Abstract

Atrazine, a widely used herbicide in agriculture due to its effectiveness and low cost, is employed to eliminate broadleaf weeds. However, its persistence and mobility in aquatic environments pose significant risks to ecosystems and human health. This emphasizes the urgent need to develop effective methods for its degradation in surface and groundwater. Heterogeneous photocatalysis, activated by visible light, has emerged as a promising solution, enabling the generation of reactive species capable of efficiently degrading organic pollutants. In this study, we designed an innovative ternary photocatalytic composite, composed of g-C₃N₄, graphene, and NiFe₂O₄, to enhance atrazine degradation under visible light in the presence of potassium peroxymonosulfate (PMS). This composite leverages the synergistic properties of its components: g-C₃N₄ efficiently absorbs visible light and generates electrons and holes necessary for degradation reactions; graphene acts as an electronic mediator, facilitating the separation and mobility of photo-excited charge carriers, thereby reducing charge recombination; and NiFe₂O₄ plays a key role in PMS activation, generating sulfate (SO₄•⁻) and hydroxyl (OH•) radicals responsible for atrazine oxidation and degradation. Compared to conventional photocatalysts, this composite offers significant advantages, notably a reduction in bandgap energy to 2.42 eV, thereby enhancing visible light absorption. Irradiation was carried out using a 48 W fluorescent lamp, optimizing the composite’s activation under visible light. Our experimental results show that 97% atrazine degradation was achieved in 5 h under optimal conditions of photocatalyst loading (0.3 g/L) and PMS concentration (1 mM) at ambient temperature. These findings highlight the potential of this material for sustainable treatment of emerging organic pollutants in contaminated waters, addressing the current challenges of water purification.