Optimization of the parameters affecting the removal of Acid Orange 7 using magnetite nanoparticlesvia response surface modeling method and Minitab 16 software

Textile and dyeing industry are the largest consumers of drinking water. Therefore, colored wastewaters that generated by the textile and dyeing industry, if discharged into the environment without treatment, can adversely affect aquatic ecosystems. In this study, magnetite nanoparticles are used to remove the dye (Acid Orange 7) from aqueous solution.
The magnetite nanoparticles were produced by a mechanical method using a planetary ball milling, and then the related physical properties were obtained and the chemical analysis was done by XRF, XRD and SEM images. The Heterogeneous Fenton process optimization was performance by response surface modeling with the help of Minitab16 software. The parameters of the initial concentration of the dye (5, 10, 15, 20 and 25 mg/L), the initial concentration of catalyst (0.4, 0.5, 0.6, 0.7 and 0.8 g/L), the initial concentration of hydrogen peroxide (5, 6.75, 8.50, 10.25, 12 mmol/L) and time of the process (8, 10, 24, 32 and 40 minutes) were selected as the factors involved in response surface modeling procedure.
Findings: Dimensions of magnetite nanoparticles were determined as less than 50 nm. The amounts of magnetite (Fe3O4) and hematite (Fe2O3) were measured to be 21/68 and 31/22 respectively. Conditions for the initial concentration of the dye (X1), the initial concentration of catalyst (X2), the initial concentration of hydrogen peroxide (X3) and the process time (X4) were obtained as 10 mg / L, 0.7 g / L, 10.25mmol / L, 32 min respectively. ANOVA high correlation coefficients for the proposed model was also obtained (adjusted-R2=0.945 and R2=0.897).
In optimal conditions, the removal efficiency of the dye (Acid Orange 7) by magnetite nanoparticles is 100%.