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北京石油化工学院2026年研究生招生接收调剂公告
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tianwei1332

铁杆木虫 (著名写手)

[交流] 改变酸度和温度,合成正钒酸盐 已有1人参与

求解答下面三个问题,谢谢:
pH在8~2范围内时,钒酸盐以“多钒酸盐”的形式存在与水溶液中。如果除去水,并在600℃焙烧,应该可以转化为正钒酸盐,是吧?

另外,如果在上述pH范围内,对钒酸盐进行的水热合成(>100℃),多钒酸盐也能转化为正钒酸盐,对吗?

钨酸盐和磷酸盐也类似吧?
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李时珍

木虫 (小有名气)


不是。
不对。
不类似。

[ 发自手机版 http://muchong.com/3g ]
2楼2014-11-16 21:32:36
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tianwei1332

铁杆木虫 (著名写手)

请看一下下面这两种办法能得到正钒酸盐吗?谢谢指导
      Pure t-LaVO4(水热法合成) 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.
3楼2014-11-17 10:39:13
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