The solubilities and solubility products of zirconium hydroxide and oxide after aging at 278, 313, and 333 K
The solubilities and solubility products of zirconium hydroxide and oxide after aging at 278, 313, and 333 K
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DOI：
10.1515/ract-2015-2461
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发表时间：
2016-03
影响因子：
1.8
通讯作者：
Taishi Kobayashi;T. Uemura;T. Sasaki;I. Takagi;H. Moriyama
中科院分区：
文献类型：
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作者：
Taishi Kobayashi;T. Uemura;T. Sasaki;I. Takagi;H. Moriyama
摘要在278、298、313和333 K下，在0.5 M离子强度的NaClO 4和HClO 4溶液中，在pH为0.3-7的范围内，测量了氢氧化锆和氧化锆在278、313和333 K下老化后的溶解度。胶体物种的粒径分布进行了研究，通过超滤使用不同孔径的膜，并通过X射线衍射检查的固相。过饱和法制备的非晶氢氧化锆（Zr（OH）4（AM））的表观溶解度随老化温度（Ta）的升高而降低，在高温下老化后得到的粒径分布表明胶体物种的生长。因此，我们建议，团聚的胶体物种和脱水和结晶的Zr（OH）4（上午）的溶解度限制固相发生在高温下老化的过程中。对于样品溶液的结晶氧化物（ZrO 2（铬）），老化温度对溶解度没有显着的影响，但在较低的温度下的溶解度数据被发现是略高于那些在较高的温度下，这意味着一小部分的无定形成分。在根据老化温度对不同固相（Zr（OH）4（s，Ta），Ta = 278、313和333 K）进行分析时，测定了不同测量温度下的溶度积（Ksp，Ta），并使用van 't霍夫方程计算了Zr 4 ++4OH-ParticZr（OH）4（s，Ta）的焓变（ΔrH○）。根据Ksp、Ta和ΔrH○值，分析了高温固相转变过程。
Abstract The solubilities of zirconium hydroxide and oxide after aging at 278, 313, and 333 K were measured at 278, 298, 313, and 333 K in the pHc range of 0.3–7 in a 0.5 M ionic strength solution of NaClO4 and HClO4. Size distributions of the colloidal species were investigated by ultrafiltration using membranes with different pore sizes, and the solid phases were examined by X-ray diffraction. The apparent solubility of zirconium amorphous hydroxide (Zr(OH)4(am)), prepared by the oversaturation method, decreased with increasing aging temperature (Ta), and the size distributions obtained after aging at elevated temperatures indicated the growth of the colloidal species. We, therefore, suggested that agglomeration of the colloidal species and dehydration and crystallization of Zr(OH)4(am) as the solubility-limiting solid phase occurred over the course of aging at elevated temperatures. For sample solutions of the crystalline oxide (ZrO2(cr)), the aging temperature had no significant effect on the solubility, but the solubility data at lower temperatures were found to be slightly higher than those at higher temperatures, implying a small fraction of the amorphous components. In the analysis of different solid phases (Zr(OH)4(s,Ta), Ta = 278, 313, and 333 K) depending on the aging temperatures, the solubility products (Ksp, Ta) were determined at different measurement temperatures, and the enthalpy change (ΔrH○) for Zr4++ 4OH– ↔ Zr(OH)4(s,Ta) was calculated using the van't Hoff equation. The solid-phase-transformation process at elevated temperatures was also analyzed based on the obtained Ksp, Ta and ΔrH○ values.