Catalytic activation of persulphate with Mn3O4 nanoparticles for degradation of acid blue 113: process optimisation and degradation pathway

Abstract

ABSTRACT The performance of the persulphate/Mn3O4 nanoparticles (PS/Mn3O4) oxidation process was investigated for the degradation of acid blue 113 (AB113) azo dye. XRD, N2 adsorption-desorption analysis, FE-SEM and EDX confirmed the successful synthesis of Mn3O4 nanoparticles. The effect of three independent variables including PS concentration, Mn3O4 dosage and solution pH on the system response was optimised by genetic algorithm (GA) and central composite design (CCD) techniques. The results of ANOVA and fit statistics (P-value < 0.0001, = 0.9772) showed that the proposed quadratic model can predict the AB113 removal efficiency with high confidence. The optimum points for PS concentration, Mn3O4 dosage and solution pH were predicted to be 61.46 mg/L, 57.69 and 3.00, respectively, by CCD method. Under these conditions, after 60 min of reaction, the maximum experimental removal efficiency of AB113 in the PS/Mn3O4 oxidation system and separate application of PS and Mn3O4 were obtained 96.70%, 18.0% and 7.0%, respectively. The pseudo-first-order rate constants of AB113 degradation the PS/Mn3O4 oxidation system and separate application of PS and Mn3O4 were 0.0597, 0.0029 and 0.0015 min−1, respectively. In this way, the synergistic effect for degradation of AB113 in the PS/Mn3O4 was determined 92.6%. Oxalic acid, naphthalen-1-ol and acetic acid were the major identified intermediates due to AB113 degradation.