| The removal of color substances from brine, which is the basic conditions of making pure magnesium salt from brine, has been studied. The magnesia-containing material with the function of absorption and desulfurization has been prepared by the reaction of magnesium salt from brine (or salt lake) with the alkali from paper-making black liquid, and the basic conditions of the reaction has been made clear through lots of experiments. The functions and characters of this material have been tested by chemical analyses, X-radio diffraction (XRD), infrared ray (IR), Brunauer, Emmett, and Teller (BET) surface area analyses and thermogravimetric-differential thermal (TG-DTA) analyses. The adsorb ability of this material to phenol and activated yellow has been also investigated in this thesis.Flocculation-adsorption method has been used to remove the organic substance in brine. PAM has been used to accelerate the sedimentation of the particles of magnesium humate, which are formed by adjust the pH to about 9.5. After separating the liquid from brine by filtration, all the color substance left in the filtrate can be removed by solid porous adsorbents completely.A magnesia-containing functional material has prepared by paper-making black liquid and magnesia sulfate, and the preparation conditions have been studied as well. Magnesium hydroxide containing gel mixture of different pH can be obtained by adjust the proportion of magnesium salt solution to black liquid. The experiment shows that the viscosity of mixture with high pH will increase in the drying process, and difficult to handle, the solid after drying is compact, which is not suit for baking. On the contrary, the mixture with low pH has low viscosity in drying process; the solid after drying is soft and porous, easy to handle. The best pH is 9.5, whichconfirmed by the analysis of the changing curve of the quantity of magnesium salt added to pH.Conventional separation methods, such as natural sedimentation, flocculation, vacuum filtration, centrifugal separation, have been proved not efficient to separate solid from the gel mixture; hydrothermal treatment can separate the solid from liquid efficiently, and most of the organic material in the black liquid can be removed, however, this method not only need long time to react, but also produce secondary wastewater. The best way to treat the gel mixture is dried directly; the raw solid produced by this means is soft and porous, which is suit for baking.The baking temperature is 450°C, which is confirmed by TG-DTA analysis to the raw solid. The constant temperature baking time- gravimetry analysis shows the sample lost more than 90% quality in the first 2 hours of baking. So bake 2 hours at 450 °C is the best baking condition.Main components in the magnesia-containing functional material is magnesia, carbon, soluble salt and silicate, which have been confirmed by chemical analysis, XRD, IR, TG-DTA, and the magnesia is of amorphism, The content of magnesia is 13~ 16%.The absorption of magnesia-containing functional material to activated yellow dye and phenol accorded with Langmuir isotherm. The saturated quantity of phenol and activated yellow are 0.4137mg/g and 43.65mg/g. the magnesia-containing functional material can adsorb more activated yellow dye than phenol... |
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