The Synthesis Of Azo-polyurethane Foam And The Separation Research Of Lithium And Magnesium By Using It

It is still focus in the simple technology of extracting lithium from brine resources that extracting lithium from brine with high concentration ratio of Mg/Li is researched. Among the methods of extracting lithium from brine, precipitation is the most mature, the lowest cost of production. But before the lithium in brine is precipitated by sodium carbonate, the concentration of magnesium ion must be reduced to not interfere with the precipitation of lithium ion.In the research,with the help of simulation structure of magnesium reagent, the 4-((4-nitrophenyl)diazenyl)-phenol was synthesized (hereinafter referred to as the nitro azo phenol).To investigate the effect of lowing concentration of magnesium ion, the two methods were used by aid of the nitro azo phenol, one of them, using it as a precipitant, magnesium ion in brine was precipitated selectively, the other, using it as the functional group of adsorption magnesium ions,it was bound to the structure of polyurethane foam plastic, and the magnesium ion in brine was adsorbed selectively by the foam.With the aid to the research of two experimental methods,The main results are listed as the following:(1) The 4-((4-nitrophenyl)diazenyl)phenol was synthetised by two-step reaction, under the conditions of raw material mole ratio, namely 4-((4-nitrophenyl)diazenyl)-phenol:sodium nitrite:sulfuric acid:phenol=1.0:1.2:3.0:1.0, diazotization reaction temperature of 0～5 ℃, diazotization of 3.5 h, azo reaction time of 5 h, the synthetic yield of 90% was obtained.(2) The purity of 4-((4-nitrophenyl)diazenyl)phenol was proved to be higher by thin layer chromatography and melting point determination. By infrared spectroscopy, mass spectrometry and ultraviolet spectrum, and the frequency of theoretical calculation for the functional groups of 4-((4-nitrophenyl)diazenyl)phenol can be good agreement with the measured vibration frequency, it was characterized that the synthetic product is the target molecule.(3) That 4-((4-nitrophenyl)diazenyl)phenol precipitated magnesium ions has been proved to be high selectivity, and the selective coefficient of precipitation is 3247. By mixing of 4-((4-nitrophenyl)diazenyl)phenol with sodium hydroxide, the magnesium ions in the solution containing lithium and magnesium ion was selectively precipitated, because the changing structure of the colloidal magnesium hydroxide precipitation, the filtration rate is greatly increased.(4) The sediment by precipitation of magnesium ions using mixed precipitant was tested by the XRD, that was proved to be changing of the structure of the precipitation.(5) After precipitated magnesium ions, the solution containing lithium was concentrated to the lithium concentration of 4 wt%, and the lithium ion was precipitated by sodium carbonate of 5 wt%, the high purity lithium carbonate can be got,the recovery rate of lithium can be reached to 99%(6) The nitro azo phenol was stepwise polymerized with formaldehyde to get linear azo resin. When synthetic conditions as follows:2.43 g of the nitro azo phenol and formaldehyde (mole ratio of 1:1.7) 70 mL, NaOH 0.6 g, the reaction temperature 90 ℃, stirring reaction time 5-6 h, the linear polymer was got, the viscosity average molecular weigh of 37241 g/mol.(7) The linear azo resin and the starting materials of polyurethane soft foam plastic polymer were polymerized togetrer to get the azo polyurethane plastic foam. The formula of starting materials formula is:polyether polyols 15.0 mL, azo resin 10.0 mL, TDI 4.5 mL, dimethyl silicone oil 5.0 mL, dibutyltin dilaurate 1.0 mL, glycerol 0.5 mL, twain-80 0.5 mL and 1.0 mL of water, and the azo polyurethane foam plastic was got, the density of 67.15 kg/m3,and the bubble porosity of 0.94 (bubble plastic material object can see appendix).(8) The corrosion rate of the azo polyurethane foam plastic are less than 1% by changing the time and temperature of the oscillation in the distilled water, it illustrate that the foam plastic is stable in the water. Infrared characterization and electron microscope scanning measurement results show that Linear azo resin was bound successfully onto the structure of polyurethane foam plastic, and bubble hole are open.(9) Under the condition of 25 ℃ and Vibration 3 h, the static adsorption capacity of magnesium ions on azo polyurethane foam plastic is 10.72mmol/L, and the static adsorption capacity of lithium ion is 0.01357 mmol/L,and the selective adsorption coefficient of 797.4.(10) Cutting up lOg of azo polyurethane foam plastic,and filling it in theφ10×400mm column, the simulated brine amount to 50mL was added into the column, and it was eluted with 0.001M HCl solution, controlling velocity of flow in 5 mL/min, the experimental result shows that the effect of dynamic lithium magnesium separation is good.(11) After the regeneration experiment, the adsorption capacity of magnesium ions is still 10.53, it illustrate that bubble plastic renewable use.