| Because of mercury-free in battery, Mo becomes one of the most harmful elements in electrolytic manganese dioxide. The Mo concentration of electrolytic manganese dioxide used for alkaline mercury-free Zn/MnO2 battery must be under 0.5μg·g-1. So the Mo concentration of MnSO4 solution which be used to prepare electrolytic manganese dioxide must be less than 0.03mg·L-1. Mo is removed more difficult than other harmful elements in MnSO4 solution, which has become a difficult problem needed to be resolved urgently in the electrolytic manganese dioxide industry.On the base of synthesis and analysis the research achievements of separation and preconcentration trace element related to the process of inorganic trace analysis, metallurgy and oceanography, et al, a novel technology is put forward to resolve the problems of deep removal trace Mo from MnSO4 solution and the problem has been resolved. The main contents of this dissertation are shown as follows:(1) When the concentration of MnSO4 is 21.0g·L-1, the dosage of NaOH is twice that of MnSO4, the reaction time is 45 minutes at ambient temperature and pH value is less than 10 of the nascent manganese suspending solution, the nascent manganese oxide show the best capabilities of removal Mo in the process of nascent manganese oxide preparation. After ageing for 148 hours, it can still satisfy the demand of removing Mo if nascent manganese oxide is used to remove Mo. Modern testing technique shows that the nascent manganese oxide is single phase Mn3O4 and have hydroxyl group.(2) The acid and alkali properties of Mn3O4 surface have been studied by adopting the acid-base titration. The results show that the positive and negative charges of Mn3O4 surface could be attributed to the protonation and deprotonation of single site≡MnOH. As pH<6.72, the surface of Mn3O4 is positively charged and exhibits the Bronsted alkalescency. As pH>6.72, the surface of Mn3O4 is negatively charged and exhibits the Bronsted acidity.The proton adsorption on Mn3O4 under different pH conditions is described with single-side nonelectrostatie model. And the model parameters got by nonlinear fitted based on the acid-base titration data are as follows: the total surface site density and protonation constants were NT=6.84×10-3 mol·g-1,Kalint=10×10-5, Ka2int= 1.49×10-10,respectively.(3) All kinds of soluble Mo species distribution have been studied in MnSO4 solution. The results show that the concentration of multimolybdenumacid radical, which could affect the adsorption process, is extraordinarily low in MnSO4 solution, so it can be ignored when the concentration of soluble Mo species is 1mg·L-1.(4) The theoretical model of the adsorption ratio with pH value was built in the system of Mo-Mn3O4-MnSO4-H2O based on nonelectrostaic model. The absolute error of adsorption rates predicted by this model is under 6% compared with experiment data.The adsorption ratio of Mo on Mn3O4 varies with pH changed in MnSO4 solution. As in the range of pH<3.65, the Mo adsorption ratio is 100%. When 3.657, the Mo adsorption ratio is about zero.(5) The ion species distribution has been studied in the system of Mo-Mn3O4-MnSO4-H2O. The results show that the mole fraction of soluble Mo species and adsorbed species varied as pH changed in solution. The predominant species on Mn3O4 surface is≡MnMoO2+,≡MnMoO4- at pH<4.5, and MoO42-,HMoO4-,H2MoO4at pH > 4.5.The Mo adsorbed on Mn3O4 belongs to specific adsorption and accords with the Freundlich constant temperature adsorption equation.(6) In the case of the MnSO4 solution which concentration is 70-200g·L-1 and Mo content is about 1mg·L-1, on the condition of pH=1.2-2.8, 30min of removal Mo time, 80℃of reaction temperature, 21g·L-1 of nascent Mn3O4 and more than 15ml·L-1 of nascent Mn3O4 dosage, the Mo absorption ratio exceeds 98.5% and the remainder Mo is under 0.015mg·L-1. The Mo in MnSO4 solution has totally reached the requirement of EMD preparation.(7) The scale up experiment of removal Mo from commercial MnSO4 solution has been studied. The results show that Mo can be removed under the optimum condition, the remainder Mo is under 0.015mg·L-1 and accords with the requirement of commercial production. Moreover, removing Mo with the nascent Mn3O4 possess the best property of scale up, which is benefit to realize industrialization. The novel method has simple process and equipment, feasible technique, reasonable cost, handling safety and no pollution, and accords with the requirement of clean production.
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