Activation of sodium percarbonate by micro amounts of copper for highly efficient degradation of acid orange 7

In recent years, activation of sodium percarbonate (SPC) has been regarded as very appealing technologies in the elimination of organic pollutants. In this work, the activation of SPC using micro amounts of Cu(II) (at μM level) towards acid orange 7 (AO7) degradation was explored. Experimental results displayed that nearly 97.5% of AO7 could be removed within 15 min using 20 µM Cu(II) and 0.4 mM SPC. Effects of Cu(II) concentration, SPC concentration, pH value and coexisting anions were investigated. Compared with conventional Fenton oxidation, which could only work under acidic pH conditions, Cu(II)-catalyzed SPC (Cu(II) /SPC) system could work under near-neutral or alkaline solutions. Furthermore, AO7 decomposition was barely impacted by Cl−, SO42− and NO3−, while 5 mM HCO3− inhibited the degradation of AO7. Electron paramagnetic resonance analysis confirmed the existence of multiple reactive oxygen species in the reaction (HO•, O2•–, 1O2). However, free radical scavenging experiments demonstrated that the degradation of AO7 was mainly due to the carbonate radicals (CO3•−) and singlet oxygen (1O2). The interaction between Cu(I) and Cu(II) was confirmed and the production of Cu(III) was proved to act as a degradation agent for AO7. The degradation of AO7 could be divided into two pathways. The study suggests a simple, economic and efficient technique for dye wastewater treatment using SPC triggered by micro-amount Cu(II).