Study On The Treatment Of Methylene Blue And Heavy Metal Ions In Wastewater By Potassium Ferrate

In the traditional sewage treatment process, chlorine based disinfectant and aluminum water purification agent can meet the requirements, but the consumption is larger, and it will produce secondary pollution and harm for the environment and human health in the use of process. Potassium ferrate is a water treatment agent of economy, efficient and environmental friendly, but the products are high cost and low purity, which limited the application of potassium ferrate.To solve this problem, the preparation process of potassium ferrate are improved and optimized in the paper, which reduce cost and obtain high purity products. And it is systematically studied that potassium ferrate degraded the dye wastewater and adsorbed heavy metal ions, the main research contents and results are as follows:(1) The potassium ferrate is prepared with the calcium hypochlorite as raw material. The products are analyzed and characterized by X-ray diffraction, canning electron microscopy, infrared absorption spectroscopy and other technical methods, the result shows that the purity of potassium ferrate solid is 92.65%, it illustrated the high-purity potassium ferrate can been prepared by this mothed.(2) The methylene blue as simulation wastewater is treated by potassium ferrate and the affects of solution pH, potassium ferrate dosage, reaction time, methylene blue initial concentration and temperature on the degradation of methylene blue are investigated, and the kinetic equation of methylene blue degradation is obtained. Experimental results show that when the potassium ferrate dosage is 0.070 g, the initial concentration of methylene blue, the pH value, temperature, reaction time was 0.04 g/L, 8.00 and 15℃, 50 min, respectively. The highest degradation rate of methylene blue is 92.14%. Methylene blue degradation kinetics equation are obtained by computer fitting, which it is Ln(C0/C) =0.00708t+0.23882(R2=0.9672). The X-ray diffraction, scanning electron microscopy, infrared spectroscopy are used to characterize and analyze degradation produced precipitation. The research find that potassium ferrate destroys the molecular structure of methylene blue in the degradation process, and the generated Fe(OH)3 can adsorb the degradation products.(3) The effects of different pH value, the dosage of ferrate dosage, reaction time, the initial concentration of heavy metal ion and temperature on potassium ferrate treatment heavy metal ions(Mn2+ and Pb2+) wastewater is studied. The optimum conditions of treatment Mn2+ are that the potassium ferrate dosage is 0.025 g, p H is 7.017, temperaturev is 15℃, Mn2+ initial concentration is 30 mg/L, time is 10 min, and the best condition of potassium Ferrate treatment Pb2+ are that the dosage of ferric is 0.010 g, temperature is 35℃, pH is 5.991, Pb2+ concentration is 10 mg/L, time is 25 min, respectively. The highest removal rate of Mn2+ and Pb2+ is 98.2% and 97.6% respectively. Compared to precipitation before and after washing, it is found that the Pb and Mn elements are evenly distributed in the surface of precipitation, and a part of the Mn2+ is oxidized to Mn4+ in the flocculation process by scanning electron microscope(SEM), Energy Dispersive Spectrometer(EDS) and X-ray photoelectron spectroscopy(XPS).