Applicability of NH2-MOF235(Fe)-derived α-Fe2O3/ZnO photocatalyst synthesized by the microwave-assisted method in the degradation of a mixture of phenolic compounds

Abstract

The NH2-MOF235(Fe)-derived α-Fe2O3-X%/ZnO (X = 15, 20, and 25 wt%) composites were successfully synthesized by microwave-assisted method followed by calcination at 450 °C. The materials were evaluated on the photocatalytic degradation of bisphenol A (BPA), 4-tert-butylphenol (4tBP), and 4-tert-octylphenol (4tOP) mixture (5 mg/L, each) under solar simulated radiation. The synthesized materials were characterized by XRD, FTIR, N2 physisorption analysis, SEM-EDS, XPS, and electrochemical assays. The NH2-MOF235(Fe)-derived α-Fe2O3 incorporation during the ZnO synthesis led to an increase in the specific surface area, improved light absorption in the visible region of the spectrum, and efficient separation of photogenerated charges. Based on the face-centered central composite experimental design matrix and RSM (response surface methodology), the optimal conditions for mineralization of the endocrine-disrupting compound mixture (42.52%) were reached using α-Fe2O3-15%/ZnO photocatalyst at pH 7.0 in 330 min (600 kJ m−2 of accumulated radiation). Moreover, 85.33, 92.82, and 92.72% degradation percentages were obtained for 4tBP, 4tOP, and BPA, respectively. Acetic acid and 2,4-di-tert-butylphenol were the main detected by-products at the end of the treatment. The α-Fe2O3-15%/ZnO material was stable for three reuse cycles for the photocatalytic degradation of the endocrine-disrupting compounds mixture. The scavenger study showed that the O2●- followed by the ●OH radical and photogenerated h+ were the main reactive species involved in the degradation of the contaminants mixture. The Vibrio fischeri assay showed that the obtained effluent was non-toxic. NH2-MOF235(Fe)-derived α-Fe2O3 improves the properties of ZnO, resulting in a promising material to eliminate BPA, 4tBP, and 4tOP mixture from aqueous samples.