Oxidative Degradation of Bisphenol A Using Recyclable Nanomaterials

Two types of nanomaterials with promising potential for bisphenol A (BPA) degradation have been synthesized using two simple methods. In the first method (mode 1; M1-MnOX), KMnO4 solution was added to pre-synthesized magnetic iron oxide nanoparticles (MC) under ultrasonic mixing and subsequently, MnSO4 solution was added dropwise to the suspension. In the second method (mode 2; M2-MnOX), the mode of reagent addition was reversed; MnSO4 solution was added to MC under continuous sonication prior to the dropwise addition of KMnO4 solution to the suspension. The nanomaterials were characterized using X-ray diffraction (XRD), transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), Fourier transform infrared spectroscopy (FTIR), and thermogravimetric analysis (TGA). The application of the nanomaterials as reusable magnetic materials for BPA degradation in water was investigated. The M1-MnOX and M2-MnOX, nanomaterials with sizes in the range 10–18 nm, were composed of iron oxide core and amorphous manganese oxide shell. Interestingly, the maximum amount of BPA degraded by M1-MnOX within 48 h was ~1 mg BPA/g wet nanoparticles, which was significantly higher than the amount degraded by M2-MnOX nanoparticles (~0.16 mg BPA/g wet nanoparticles). Furthermore, the M1-MnOX nanoparticles could be efficiently reused four successive times without major loss of degradation activity. These low cost nanomaterials could be easily recovered by magnetic separation and washed for reuse, overcoming both filtration and reuse problems often associated with conventional use of colloidal manganese oxides as sorbents or catalysts.