Degradation of 2, 4-D acid using Mn²⁺ as catalyst under UV irradiation

In this paper, the oxidative degradation of 2, 4-dichlorophenoxyacetic acid (2, 4-D) using Mn²⁺/H₂O₂ reagent under UV irradiation was studied. The results show that 2, 4-D was degraded more completely in Mn²⁺/H₂O₂ solution than traditional Fenton solutions. The effects of the concentration of Mn ²⁺, H₂O₂ and pH were also investigated. And under the optimal condition of c-_Mn^{2 +} 1.48×10 ^-4 mol/L, c-&H;2 O 2 8.99×10^-5 mol/L and pH 3.38, the formation of •OH was the most, both the decomposition rate of H₂O₂ and the degradation rate of 2, 4-D were the fastest. In addition, the photoreaction process was monitored using spin-trapping electron paramagnetic resonance (EPR), and the results indicated that the oxidative process was predominated mainly by the hydroxyl radical (•OH) gennerated in the system.