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Sorption pH dependance of strontium/calcium by sodium nonatitanate
Chemosphere ( IF 8.8 ) Pub Date : 2018-03-13 , DOI: 10.1016/j.chemosphere.2018.02.017
Arnaud Villard , Guillaume Toquer , Bertrand Siboulet , Philippe Trens , Agnès Grandjean , Jean-François Dufrêche

Sodium nonatitanate powder is a layered material containing some potential exchangeable sodium ions between layers. In this work, sorption mechanism of this material has been studied and modeled at the solid-liquid interface. In particular, the ion-exchange mechanism is up to now not entirely known and especially the role of the pH on sorption properties. To investigate this latter, the solid is first equilibrated with inert acidic and base (nitric acid and triethylamine) for which the co-ions nitrate and triethylammonium do not penetrate the solid. The exchange between proton or divalent ions (strontium or calcium), and the sodium initially located in the sodium nonatitanate, is characterized through capillary ionic chromatography and conductivity experiments. To understand and explain the sorption properties, we modeled the equilibrium constant of different exchange reactions as a function of the solution pH. The equilibrium constants of the strontium/sodium and the calcium/sodium exchange have been obtained. We have shown the important role of the pH on the sorption rate of the strontium and moreover the hydrolysis rate of the sodium nonatitanate is calculated. We found that one eighth of sodium is spontaneously hydrolysed in aqueous phase whereas seven-eighths are exchanged by different divalent cations (strontium or calcium). Strontium and calcium exhibit similar exchange curves and competition with the proton adsorbed is modeled with global equilibrium constant. The prediction is in agreement with the conductivity experiments and the global extraction isotherms.



中文翻译:

壬二酸钠对锶/钙的吸附pH依赖性

九烷基钛酸钠粉末是一种层状材料,在层之间含有一些潜在的可交换钠离子。在这项工作中,已经研究了这种材料在固液界面的吸附机理并进行了建模。特别是到目前为止,离子交换机理尚不完全清楚,尤其是pH对吸附性能的作用尚不完全清楚。为了研究后者,首先用惰性酸和碱(硝酸和三乙胺)平衡固体,硝酸盐和三乙铵的共离子不会渗透到固体中。质子或二价离子(锶或钙)与最初位于九钛酸钠中的钠之间的交换通过毛细管离子色谱法和电导率实验来表征。为了理解和解释吸附特性,我们将不同交换反应的平衡常数建模为溶液pH的函数。获得了锶/钠和钙/钠交换的平衡常数。我们已经显示了pH对锶的吸附速率的重要作用,此外,还计算出了壬二酸钠的水解速率。我们发现八分之一的钠在水相中自发水解,而八分之八则被不同的二价阳离子(锶或钙)交换。锶和钙表现出相似的交换曲线,并且利用整体平衡常数来模拟与吸附质子的竞争。该预测与电导率实验和整体提取等温线一致。获得了锶/钠和钙/钠交换的平衡常数。我们已经显示了pH对锶的吸附速率的重要作用,此外,还计算出了壬二酸钠的水解速率。我们发现八分之一的钠在水相中自发水解,而八分之八则被不同的二价阳离子(锶或钙)交换。锶和钙表现出相似的交换曲线,并且利用整体平衡常数来模拟与吸附质子的竞争。该预测与电导率实验和整体提取等温线一致。获得了锶/钠和钙/钠交换的平衡常数。我们已经显示了pH对锶的吸附速率的重要作用,此外,还计算出了壬二酸钠的水解速率。我们发现八分之一的钠在水相中自发水解,而八分之八则被不同的二价阳离子(锶或钙)交换。锶和钙表现出相似的交换曲线,并且利用整体平衡常数来模拟与吸附质子的竞争。该预测与电导率实验和整体提取等温线一致。我们已经显示了pH对锶的吸附速率的重要作用,此外,还计算出了壬二酸钠的水解速率。我们发现八分之一的钠在水相中自发水解,而八分之八则被不同的二价阳离子(锶或钙)交换。锶和钙表现出相似的交换曲线,并且利用整体平衡常数来模拟与吸附质子的竞争。该预测与电导率实验和整体提取等温线一致。我们已经显示了pH对锶的吸附速率的重要作用,此外,还计算出了壬二酸钠的水解速率。我们发现八分之一的钠在水相中自发水解,而八分之八则被不同的二价阳离子(锶或钙)交换。锶和钙表现出相似的交换曲线,并且利用整体平衡常数来模拟与吸附质子的竞争。该预测与电导率实验和整体提取等温线一致。锶和钙表现出相似的交换曲线,并且利用整体平衡常数来模拟与吸附质子的竞争。该预测与电导率实验和整体提取等温线一致。锶和钙表现出相似的交换曲线,并且利用整体平衡常数来模拟与吸附质子的竞争。该预测与电导率实验和整体提取等温线一致。

更新日期:2018-03-14
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