Transformation Of Hexagonal Birnessite In Different Environments

In this study, syntheses conditions and reaction mechanism of birnessite in acid medium and transformation of birnessite were systematically investigated by using analysis techniques such as XRD, FTIR, TEM, SEM ect. In addition, in order to have a thorough understanding on the transformation of hexagonal birnessite and underlying mechanism in the stimulated surface environment substructural characteristics of hexagonal birnessite under simulated surface environment, focuses the effect of surface environment and substructural characteristics of hexagonal birnessite on mineral transformation.The main contents of dissertation were summarized as follows:(1) Temperature, inorganic ions and small molecule organic acids affact the transformatiom of the hexagonal birnessite. Under surface environment, the higher the condition environment temperature, the faster the hexagonal birnessite conversion rate, the lower the solution pH, the faster conversion rate of hexagonal birnessite.With the increasing concentration of K+ and NO3- in the solution of water has the inhibitory effect of hexagonal birnessite; With the increase of SO42- concentration in the solution the transformation of hexagonal birnessite increased, when the solution in the presence of K+ and SO42- at the same time, the transformation of SO42- hexagonal birnessite promoting effect is greater than the inhibition of K+; Mn2+ in the solution, has a promoting effect of hexagonal birnessite, with the increase of concentration, the conversion rate increased, converted products also changed, when the content of Mn2+ 0.1 mmol/L, hexagonal birnessite products for a single mineral cryptomelane, when the content of Mn2+ 1 mmol/L, 10 mmol/L, 100 mmol/L, converted products are hexagonal birnessite and Nsutite.The small molecule organic acid radical in acetic acid, butyric acid, caproic acid has a promoting effect on hexagonal birnessite, with the increasing of concentration of organic acid radical, the conversion rate of hexagonal birnessite increased.(2) The substructural characteristics potassium content of hexagonal birnessite affects the conversion rate of manganese, potassium content is higher, the slower the hexagonal birnessite conversion rate.(3) The soil common hydrosialite such as silica, clay mineral kaolinite, smectite, goethite has inhibitory effect on the transformation of hexagonal birnessite, when the higher the hydrosialite content in the solution, the lower the hexagonal birnessite transformed.(4) Using the images of TEM and electron diffraction spectrum study the transformation mechanism of the hexagonal birnessite. In the process of transformation the hexagonal birnessite transformed from the chip package to nanometer linear, can be found under the transmission electron microscopy(SEM), outside-in gradually into nanometer thin plate assembly line, description of the hexagonal birnessite is dissolved minerals of recrystallization process.