Preparation Of Ferrate Solution With Red Mud As Reagent And Experimental Study On The Lake Water Treatment Using Ferrate Solution

Potassium ferrate (VI) is an environmental-friendly agent and has a good prospect for application in water and wastewater treatment because of its strong oxidation, quick adsorption and flocculation, vigorous sterilization and deodorization ability. It is now, however, can not been produced and applied on large scale due to the complicated preparing processes, high cost of the product and unstable in the air environment, etc.In this article, sodium ferrate solution was prepared with hypochlorite-oxidation method using red mud as iron sources. The effects of reaction time, reaction temperature, amounts of reactants on the preparation of ferrate were studied. On the basis of prepared sodium ferrate solution, solid potassium ferrate was prepared and the stability of ferrate was also characterized in this study. It can be found that: (1) the concentration of FeO42-was 2.78×10~3mg/L at the optimal condition when the weight of red mud is 60g, sodium hydroxide and sodium hypochlorite was 30% excessive, the temperature was controlled to be 60°C with water bath and the reaction time is settled to be 35min. (2) sodium ferrate solution was placed in a saturated solution of KOH and made them crystallize,it could get the solid potassium ferrate,when the solid potassium ferrate was recrystallized,The purity of the production was found to be 93.56%. (3) Potassium ferrate solution possesses a maximum absorption at the wavelength of 508nm by ultraviolet spectrum. So the obtained product could be proved to be potassium ferrate, which was further confirmed by the x-ray diffraction (XRD) test. (4) Several factors affecting the stability of ferrate such as temperature, pH values, solvents and quality of containers were studied in the paper. Under the same condition of preparation and preservation, stability of sodium ferrate obtained with red mud is better than that with ferric trichloride as iron sources after eight days.Eutrophication occurs more and more popular in lake water bodies, which leads to algal blooms and thus the permanently degraded of water quality. Longting lake water of kaifeng was collected and treated by sodium ferrate in this study. The experimental results show that when 6ml of sodium ferrate and 30mg/L aluminum sulfate was added to the lake water, the removal rate of algae, turbidity, ammonia nitrogen and COD could reach to 88.64%, 87.1%, 82.59% and 83.56%, respectively.Accordingly, it is completely feasible to prepare ferrate using red mud as iron sources. It not only extends the options of iron sources to prepared ferrate, but also turns waste of red mud into treasure. And the sodium ferrate solution can treat lakes water effectively, which provides a way to make use of ferrate.