| Autor: |
Shoji Kasahara, Tomio Takasu, Nobuaki Nagano, Yuki Mikoshi, Hideyuki Itou, Naotaka Sakamoto |
| Předmět: |
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| Zdroj: |
Materials Transactions; 2020, Issue 10, p1930-1939, 10p |
| Abstrakt: |
In order to understand the characteristics of the wastewater treatment method using zero-valent magnesium granules, the reaction between an aqueous solution containing boron and zero-valent magnesium granules was investigated by experiments and a reaction rate model. Particular attention was paid to the effect of adding hydrochloric acid before adding zero-valent magnesium and to the effect of adding sodium hydroxide to adjust the pH to 10.5 after 110 minutes. The following findings were obtained. The relationship between the pH and the dissolved magnesium concentration over time is determined by a reaction formula in which zero-valent magnesium granules react with an aqueous solution to generate Mg2+ ions while generating hydrogen. When magnesium hydroxide is produced, the pH becomes constant over time. Increasing the concentration of hydrochloric acid lowers the pH value reached. This relationship is determined in equilibrium with magnesium hydroxide. The reaction rate of the zero-valent magnesium granules is determined as the first-order reaction of the hydrogen ion activity when the pH was lower than 2.3 or higher than 8.5, and as the zero-order reaction of the hydrogen ion activity at pH from 2.3 to 8.5. The amount of magnesium hydroxide produced without the addition of sodium hydroxide is determined by the above-described reaction rate model of zero-valent magnesium granules. The boron concentration of the solution when the pH is adjusted to 10.5 by adding sodium hydroxide is determined by the Langmuir-type sorption isotherm of boron to the magnesium hydroxide produced. As described above, the behavior of removing boron from an aqueous solution using zero-valent magnesium granules can be well reproduced by the simple reaction rate model used in this study, and it can be said that it is useful for process design. [ABSTRACT FROM AUTHOR] |
| Databáze: |
Complementary Index |
| Externí odkaz: |
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