Oxalic Acid Monomethyl Hydrazine Synthesis, Decomposition And Its Application Of Sewage Volume Washing

The preparation, stability and decomposition of methyl-hydrazine oxalate (MHOX) were investigated.The white needles of MHOX were obtained as the solution ofMHOX was added into the anhydrous alcohol. The molecularformula of MHOX is (CH₃N₂H₄)₂C₂O₄. The aqueous solution ofMHOX is stable at ambient temperature.The kinetics of redox reaction between MHOX and hydrogenperoxide was studied. By investigating the influence of variousfactors on H₂C₂O+4-H₂O₂ system, the kinetic rate equation isobtained as follows:- d[Ox]/dt = k [Ox][H₂O₂][ H⁺]⁰.34The rate constant of reaction k = 1.8±0.057(mol/L)^-1.34h^-1 at 90℃. Half decomposition time, t₁/2(h), for oxalic acid in 0.5mol/LHNO, at 90℃ is:t_l/2=0. 49/ [H₂O₂]Using H₂O₂ as an oxidant, the rate of decomposition of methyl-hydrazine is higher than that of oxalic acid. The decompositionreaction is as follows:H₂O₂ + CH₃N₂H₃ → N₂ + CH₄ + 2H₂OBy investigating the influence of concentration of CH₃N₂H₃ andH₂O₂ on reaction, the kinetic rate equation in the experimentalconditions is presented as follows:'; d[CH,N,H,l/dt = k [CH,N,H,][H,O,]The rate constant of reaction k=0.67 t 0.038(mol/L)-'h-' at 29'C. The rate of reaction of MHOX with H2O, depends on that ofoxalic acid.The washing efficiency of 3 0%TBP-OK containing micro-quantity of uranium was studied with MHOX. The effects ofwashing time, concentration of washing solution, phaseratio(A/O), molar ratio of [CH,N,H.+]/[C,O.'-] and irradiationdose on the wa'shing efficiency were investigated. Theexperimental results show that the washing efficiency of uraniumfrom 30%TBP-OK with MHOX is as same as that with Na,CO,.The washing efficiency of Pu from 30%TBP-OK and Pu andAm from DHDECMP(CMP) with MHOX was also studiedrespectively. Experimcnts show that the washing efficiency of Puand Am with MHOX is slightly higher than that with Na,CO,.The concentration of uranium remained in 3 0%TBP-OK isabout lmg/L after the organic phase containing more than40mg/L was washed in four-stage countercurrent cascade withMHOX.Therefore, it is potential that MHOX would be used as asalt-free washing reagent for cleaning extractant, such as TBPused in Purex Process and CMP used in CMP Process.