| Cuprous oxide is a kind of important inorganic material, which is extensively used in the fields of coating, glass, porcelain, plastics, agriculture and the industrial catalyst. The consumption of cuprous oxide increases year after year in our country, and the research on it is more active in recent years.Though there are many methods to prepare cuprous oxide currently, it seldom gets cuprous oxide with equirotal grains and stable characterization, and many methods are very complicated in operation.Cuprous oxide can be prepared from cupric sulfate and sodium sulfite solution. The raw material, such as cupric sulfate and sodium sulfite, is easy to obtain. The operation is very simple, and no special demand on equipment. The sample gotten by this method has no impurity. However, the sulfur dioxide brought in the reaction process dissolves into the reactive solution, which makes the solution acidity increase, so the yield and content of cuprous oxide are reduced greatly.Sodium hydroxide and sodium carbonate are used to adjust the valve of pH, which leads to the local chemical reaction and create copper hydrate. When copper hydrate is heated, it changes into copper oxide, which makes the production impure.In this paper, the buffer solution of acetic acid and sodium acetate (HAc-NaAc) is first used to adjust the valve of pH. In the buffer system of HAc-NaAc, pure cuprous oxide was prepared from cupric sulfate and sodium sulfite solution in common condition and hydrotheimal synthesis respectively. The sample was analyzed and characterized by using Chemistry Analysis, SEM, XRD, and DTA - TG. The optimal reaction condition of preparing cuprous oxide is confirmed in common condition and hydrothermal synthesis respectively, and the kinetics of oxidation wasalso considered.The results of single-factor experiment and orthogonal experiment in common condition showed that the main factor which influenced the production were reaction time, reaction temperature, the dosage of reactant, and the ratio of sodium sulfite and cupric sulfate. The optimal experiment conditions in common preparation were ninety minutes of reaction time and 368K of reaction temperature, the dosage of the buffer reagent was twice as much as the dosage of reaction solution, and the best ratio of sodium sulfite and cupric sulfate solution was 1.2. The yield of cuprous oxide was 86% and the content of cuprous oxide was 98.47%, the cumulate density was 0.6548g/cm3, and the average particle size is about 1 urn.The results of single-factor experiment and orthogonal test experiment of hydrothermal synthesis method showed that the main factors which influenced the preparation were reaction time, reaction temperature, the dosage of reactant, and the filling factor. The optimal experiment conditions of the hydrothermal synthesis method were twelve hours of reaction time and 353K of reaction temperature, the dosage of the buffer reagent was four times as much as the dosage of reactive solution, and the best filling ratio was 0.80. The yield was 88%, the content was 98.02%, the cumulate density was 0.8319g/cm3, and the particle diameter was at the range from 6um to 1 Oum.The cuprous oxide produced with these two methods was analyzed by DTA - TG analysis method. The temperature of the cuprous oxide prepared in common condition oxidized was 643K, and the weight was increased by 11% in TG curves accordingly. However, the temperature of the cuprous oxide produced with the hydrothermal synthesis method oxidized was 733K, and obvious increase 11% of weight could be found in the curve of TG too.The parameters of kinetics of oxidation were studied by Kissinger method. The result was that activation energy of cuprous oxide prepared in common condition was 204.03KJ-mor', the pre-exponential factor was 2.45^1016, and the reaction order was 1.06. Correspondingly, the activation energy of cuprous oxide with the hydrothermal synthesis method was 727.45KJ-mo]"', the pre-exponential factor was 9.16x1051, andthe reaction order was 1.02. |
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