| The objective of this research was the development of new methods for the synthesis of metal molybdates using molybdenum trioxide. The latter is also used to remediate heavy metal-contaminated water. In the case of uranium, it was found that Moo3 could absorb up to 165% by weight of uranium when reacted with uranyl acetate. The insoluble product was identified as the mineral umohoite [(UO2)MoO4(H2O)](H 2O). A regeneration process was successfully achieved by treating the product with an aqueous solution of 15% ammonium hydroxide. The recovery of molybdenum oxide was 98.9% by weight and the efficiency of separation of uranium from umohoite was 96.1% by weight. When applying the same technique to different transition metals and alkaline-earth metals, the products obtained after heating at moderate temperatures were in the form of MMoO4 (M= Mn, Co, Zn, Cd, Pd, Ca, Sr, Ba). The latter could be used as heterogeneous catalysts for several oxidation processes. The method was further extended to synthesize lanthanide molybdates. In the case of lanthanum, a mixed metal oxyacetate was obtained that converted to the cubic form of La2Mo2O 9 (an oxide conductor) upon heating to 550°C. On the other hand, the reaction of gadolinium acetate with molybdenum oxide yielded hydrous mixed metal oxides that converted to the ferroelectric Gd2(MoO4 )3 at higher temperature. Molybdenum trioxide was determined to be an excellent tool for removal of heavy metals from water. The process involves the formation of mixed metal molybdates, which play significant role in many areas of chemistry, physics and material sciences. (Copies available exclusively from MIT Libraries, Rm. 14-0551, Cambridge, MA 02139-4307. Ph. 617-253-5668; Fax 617-253-1690.)... |
