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. 2023 Aug 24;13(36):25408-25424.
doi: 10.1039/d3ra03612j. eCollection 2023 Aug 21.

Optimization of the photocatalytic degradation of phenol using superparamagnetic iron oxide (Fe3O4) nanoparticles in aqueous solutions

Edris Bazrafshan  1   2 , Leili Mohammadi  3 , Amin Allah Zarei  1   2 , Jafar Mosafer  2   4 , Muhammad Nadeem Zafar  5 , Abdollah Dargahi  6   7
Affiliations

Optimization of the photocatalytic degradation of phenol using superparamagnetic iron oxide (Fe3O4) nanoparticles in aqueous solutions

Edris Bazrafshan et al. RSC Adv. .

Abstract

The present work was carried out to remove phenol from aqueous medium using a photocatalytic process with superparamagnetic iron oxide nanoparticles (Fe3O4) called SPIONs. The photocatalytic process was optimized using a central composite design based on the response surface methodology. The effects of pH (3-7), UV/SPION nanoparticles ratio (1-3), contact time (30-90 minutes), and initial phenol concentration (20-80 mg L-1) on the photocatalytic process were investigated. The interaction of the process parameters and their optimal conditions were determined using CCD. The statistical data were analyzed using a one-way analysis of variance. We developed a quadratic model using a central composite design to indicate the photocatalyst impact on the decomposition of phenol. There was a close similarity between the empirical values gained for the phenol content and the predicted response values. Considering the design, optimum values of pH, phenol concentration, UV/SPION ratio, and contact time were determined to be 3, 80 mg L-1, 3, and 60 min, respectively; 94.9% of phenol was eliminated under the mentioned conditions. Since high values were obtained for the adjusted R2 (0.9786) and determination coefficient (R2 = 0.9875), the response surface methodology can describe the phenol removal by the use of the photocatalytic process. According to the one-way analysis of variance results, the quadratic model obtained by RSM is statistically significant for removing phenol. The recyclability of 92% after four consecutive cycles indicates the excellent stability of the photocatalyst for practical applications. Our research findings indicate that it is possible to employ response surface methodology as a helpful tool to optimize and modify process parameters for maximizing phenol removal from aqueous solutions and photocatalytic processes using SPIONs.

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Conflict of interest statement

The authors declare no competing interests.

Figures

Fig. 1
Fig. 1. A schematic of the photocatalytic process and hydroxyl radical generation.
Fig. 2
Fig. 2. The FTIR spectrum of SPIONs.
Fig. 3
Fig. 3. (a) Particle size distribution of SPIONs obtained by DLS, TEM micrograph of SPIONs (b) before the phenol adsorption process, (c) and (d) after the phenol adsorption process.
Fig. 4
Fig. 4. XRD powder pattern of SPIONs before (a) and after (b) the adsorption process.
Fig. 5
Fig. 5. Magnetic behavior of SPIONs at 300 K.
Fig. 6
Fig. 6. Absorption spectrum of phenol solution before and after photodegradation with SPIONs.
Fig. 7
Fig. 7. Graph of correlation between experimental and predicted returns values.
Fig. 8
Fig. 8. The studentized residuals and normal % of probability residuals for removal of phenol.
Fig. 9
Fig. 9. 2D contour and 3D surface plot of the interaction effect of phenol concentration and pH on phenol removal efficiency by a photocatalytic degradation process at constant SPION ratio and time.
Fig. 10
Fig. 10. 2D contour and 3D surface plot of the interaction effect of time and pH on removal efficiency of phenol by photocatalytic degradation process at constant SPION ratio and phenol concentration.
Fig. 11
Fig. 11. 2D contour and 3D surface plot of the interaction effect of UV/SPION ratio and pH on removal efficiency of phenol by a photocatalytic degradation process at constant time and phenol concentration.
Fig. 12
Fig. 12. 3D surface and contour plot of the interaction effect of phenol concentration and time on phenol removal efficiency by photocatalytic degradation process at constant pH and UV/SPION ratio.
Fig. 13
Fig. 13. 3D surface and 2D contour plot of the interaction effect of phenol concentration and UV/SPION ratio on phenol removal efficiency by a photocatalytic degradation process at constant time and pH.
Fig. 14
Fig. 14. The 3D surface of the interaction effect of time and UV/SPION ratio on RB19 removal efficiency by photocatalytic degradation process at constant pH and phenol concentration.
Fig. 15
Fig. 15. (a) The desirability effect for phenol removal and (b) desirability effect of the individual parameters.
Fig. 16
Fig. 16. Recovery of superparamagnetic nano-absorbent (Fe3O4) after five times in optimal conditions.
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