The preparation and oxidative properties of ferrate ion (FeO4^2-). Studies directed toward its use as a water purifying agent. Phase-1.
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Abstract
The use of FeO4^2- in the treatment of deep-well and Missouri River water has been evaluated with respect to many variables. It is found that the addition of FeO4^2- effectively reduces the amounts of iron, manganese, cadmium, mercury, lead, cobalt, nickel, arsenic, and boron to values less than the detectable quantities with our instrumentation. This is done with less than 50 ppm of added Na2FeO4. The presence of river silt has no effect and the reagent is effective above a pH of 7. In more acidic water some base such as CaO must be added to prevent the spontaneous FeO4^ 2- decomposition but less than is presently being used in plants around the country. For iron removal, 1-2 ppm FeO4^2- removes iron to less than .02 ppm giving an easily filterable precipitate. Any excess FeO4^2- decomposes in 15-20 minutes (depending on temperature and acidity) precipitating Fe(OH)3 and giving O2 to the system. No residual reagent remains. Many organic substances are oxidized to CO2 and N2 ultimately while H2S goes to S8 and NO2 to NO3 and NH3 to a series of products. FeO4^2- is extremely deadly to many river water bacteria as well as to selected strains of laboratory bacteria. It approaches the effectiveness of OCl (Cl2) in the tests so far conducted. (1-5 ppm) FeO4^2- removes essentially all the test bacteria in laboratory studies. Test virus are also highly susceptible to its action and the damage is permanent. It has the further advantage of leaving no residue or residual action after a short reaction period and filtration. The time of contact need be only short, one minute or less for it to be effective at 5-25 degrees C. The preparation of Na2FeO4 can be carried out by electrolyzing scrap iron in 50 percent NaOH solution giving about 50 percent theoretical conversion to the ion. The by-product is H2 which has many industrial uses. Thus there is reason to believe that Na2FeO4 can be prepared cheaply, shipped as a stable concentrated NaOH solution and metered as a liquid into water purification streams. This study has shown that Na2FeO4 is extremely effective for removing transition metal ions and other foreign ions as well as killing bacteria and clarifying well water and river water. It may be the final treatment of choice when industrial production of the reagent is accomplished.
This material is based upon work supported by the U.S. Geological Survey and the Missouri Water Center under the Grant/Cooperative Agreement.
The views and conclusions contained in this document are those of the authors and should not be interpreted as representing the opinions or policies of the U.S. Geological Survey or Missouri Water Center. Mention of trade names or commercial products does not constitute their endorsement by the U.S. Geological Survey or Missouri Water Center.
This material is based upon work supported by the U.S. Geological Survey and the Missouri Water Center under the Grant/Cooperative Agreement.
The views and conclusions contained in this document are those of the authors and should not be interpreted as representing the opinions or policies of the U.S. Geological Survey or Missouri Water Center. Mention of trade names or commercial products does not constitute their endorsement by the U.S. Geological Survey or Missouri Water Center.