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tianwei1332鐵桿木蟲 (著名寫手)
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[交流]
改變酸度和溫度,合成正釩酸鹽 已有1人參與
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求解答下面三個問題,謝謝: pH在8~2范圍內時,釩酸鹽以“多釩酸鹽”的形式存在與水溶液中。如果除去水,并在600℃焙燒,應該可以轉化為正釩酸鹽,是吧? 另外,如果在上述pH范圍內,對釩酸鹽進行的水熱合成(>100℃),多釩酸鹽也能轉化為正釩酸鹽,對嗎? 鎢酸鹽和磷酸鹽也類似吧? |
鐵桿木蟲 (著名寫手)
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請看一下下面這兩種辦法能得到正釩酸鹽嗎?謝謝指導 Pure t-LaVO4(水熱法合成) was prepared through several steps using a hydrothermal method. First, a predetermined amount of La2O3 was dissolved in 6 M HNO3 solution. Then, the obtained La(NO3)3 solution was mixed with 0.4 M NH4VO3 at the V:La mole ratio of 1:1 to form a precipitate, followed by adjusting the pH of the new mixture to 7 with a 2 M NH3 solution and transferring it into a 100-mL Teflon-lined stainless-steel autoclave. The autoclave was sealed and maintained at 180°C for 24 h and then air-cooled to room temperature. The resulting products were filtered, washed with deionized water, and dried at 80°C for 12 h. Pure m-LaVO4(普通沉淀法) was prepared via a precipitation method. Specifically, 20 mL of0.4 M NH4VO3 and 20 mL of 0.4 M La(NO3)3 were used for the mixing and generation of a precipitate. The pH of the mixture was controlled at 5, using a 2 M NH3 solution. After aged at room temperature for 30 min, the precipitate was filtered, washed three times by deionized water, dried at 100 ℃ for 12 h and calcined at 600 °C for 4 h.The LaVO4/g-C3N4 composite catalysts were prepared as follows. LaVO4 and g-C3N4 with given ratios were mixed and ground in an agate mortar for 20 min, and then calcined at 450℃ for 2 h to obtain the LaVO4/g-C3N4 catalyst. The actual LaVO4 concentration was determined with thermogravimetry(TG) experiments (see Figure S1 in the Supporting Information). For simplification, the synthesized LaVO4/gC3N4 composites are denoted as xwt %t-LC or xwt %m-LC,in which xrepresents the LaVO4 concentration. |
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