Synthesis Of Fe And Mn Oxides And Their Applications In Waste Water Treatment

This paper concerntrates on the synthesis of Fe/Mn oxides and their applications in waste water treatment.α-FeOOH nanorods was synthesized via one-step method at room temperature.The sample was characterized byâ…©-ray powder diffraction(XRD)and transmission electron microscopy(TEM).It was employed for the decoloration of methylene blue(MB)in the presence of H₂O₂ under natural light.For comparison,two kinds ofα-Fe₂O₃ nanonods were obtained by calciningα-FeOOH nanorods at 450℃and 600℃and used as catalysts, respectively.Experiments indicate thatα-FeOOH nanorods have the best catalytic efficiency,and the decoloration rate of MB reaches 95.41%at 230 min;the catalytic activity of one-dimensional nanostructuredα-FeOOH is much higher than that ofα-FeOOH particle.The catalytic decoloration of MB withα-FeOOH nanorods was tracked by ultraviolet-visible(UV-Vis)and fourier transform infrared spectrometer(FT-IR),at the same time,the effect of initial concentration of MB, H₂O₂ and initial pH value on the decoloration rate of MB was also investigated.The degradation rate follows pseudo-first order kinetics,and rate constant is 0.095 min^-1.Nanostructuredε-MnO₂ made up of nanowhiskers was successfully prepared with KMnO₄ and MnSO₄ as the raw materials at room temperature.â…©-ray powder diffraction(XRD),transmission electron microscopy(TEM)and specific surface area(BET)were used to characterize the obtained products.With as-prepared nanostructuredε-MnO₂ as adsorbent,the decoloration of methylene blue was studied.UV-vis and FT-IR analysis indicate that the decoloration of methylene blue results from its adsorption on nanostructuredε-MnO₂.The influences of reaction conditions such as initial concentration of methylene blue,temperature,pH value and the adsorbent dosage on the removal efficiency of methylene blue were studied, respectively.Experiments show that initial concentration of methylene blue is the key factor affecting the decoloration efficiency.The nanostructureε-MnO₂ was also used as catalysts to decompose simulated phenol wastewater.This catalytic reaction is simple and does not need extra oxidants.Based on the fluorescence spectroscopy(FL)test,the removal of phenol is up to 80.4%within 80 min.The intermediate products during the degradation process of phenol were investigated with the use of high performance liquid chromatography(HPLC).The possible decomposition path of phenol is proposed. Kinetic study of the catalytic reaction shows that the reaction kinetics order is 1.64 and the reaction rate constant is 0.0075 min^-1.