Comparative study on ozonation and catalytic ozonation using MgO@Fe3O4 magnetic nanoparticles for the removal of phenylamine from aqueous solutions

Abstract

ABSTRACT In this research, the performance of catalytic ozonation process (COP) with MgO@Fe3O4 magnetic nanocomposite for phenylamine removal from aqueous solution in a batch environment was evaluated. The features of the catalyst were determined by the FE-SEM, EDS, XRD, VSM and TEM techniques. The effect of several operating parameters such as solution pH, reaction time, catalyst dosage, ozone dose and the initial phenylamine concentrations was investigated in parallel with a single ozonation process (SOP). The effect of the scavengers was assessed. Possible mechanisms, by-products identification and pathway of degradation were also performed. The mineralisation rate was analysed with COD and TOC tests, respectively. The results indicated that the highest efficiency of phenylamine degradation (98.5%) and mineralisation with COD (74%) and TOC (51%) happens in the COP under the optimum conditions (pH = 11.0, reaction time = 30 min, catalyst dosage = 2.0 g/L, ozone dose = 0.38 g/h, phenylamine concentration = 10 mg/L), respectively. The experimental data were in good agreement with pseudo-first-order kinetic model. The toxicity of untreated phenylamine solution revealed that have higher acute toxicity for Daphnia magna than the phenylamine treated solution with COP. The hydroxyl radicals were dominant species during phenylamine degradation. The reusability of the catalyst was evaluated, indicating a 4.7% decrease in performance after six consecutive cycles of the process. As compared to SOP, a significant synergistic effect was observed between ozone and MgO@Fe3O4. It can be concluded that application of MgO@Fe3O4 in catalytic ozonation process is as a successful and promising method for phenylamine degradation of aqueous solutions.