Thermodynamic analysis on decomposition of calcium oxalate with acid

被引：0

作者：

Cao C. ^{[1
,2
]}

Peng Z. ^{[1
]}

Lu H. ^{[1
]}

Lü Y. ^{[1
]}

Fu A. ^{[1
]}

机构：

[1] Division of Materials Metallurgy and Chemistry, Jiangxi University of Science and Technology, Ganzhou

[2] Fujian Changting Golden Dragon Rare-earth Co. Ltd., Longyan

来源：

Zhongnan Daxue Xuebao (Ziran Kexue Ban)/Journal of Central South University (Science and Technology) | 2023年 / 54卷 / 02期

关键词：

calcium oxalate; decomposition; hydrochloric acid; sulfuric acid; thermodynamics;

D O I：

10.11817/j.issn.1672-7207.2023.02.003

中图分类号：

学科分类号：

摘要：

In order to clarify the thermodynamics of decomposing calcium oxalate residue with acid, based on the principles of simultaneous equilibrium, mass conservation and electric neutrality, a series of thermodynamic equilibrium diagrams for decomposition of calcium oxalate using hydrochloric acid and sulfuric acid as decomposition agents were calculated, drawn, and verified by experiments. The results show that the trend of the single factor experimental results is consistent with the thermodynamic calculation results, and the experimental values are highly consistent with the calculated values in some cases. The calcium oxalate is a relatively stable precipitate, and maintains a low level of dissolution in the pH range of 4 to 13. In the hydrochloric acid system, calcium chloride and oxalic acid can significantly inhibit the dissolution of calcium oxalate, while in the sulfuric acid system, the formation of calcium sulfate can maintain the calcium concentration at a low level, thus promoting the decomposition of calcium oxalate. The ratio of sulfuric acid involved in the decomposition reaction of calcium oxalate increases with increasing initial acidity, and the reaction ratio of sulfuric acid can reach 39.7% when the sulfuric acid concentration is 4 mol/L. The reaction ratio of hydrochloric acid is hardly affected by the initial acidity and remains at a low level of 5.4%. In addition, the reaction ratio of sulfuric acid decreases with increasing initial oxalic acid concentration, but at the same initial oxalic acid concentration, the reaction ratio of sulfuric acid involved in the decomposition reaction of calcium oxalate is significantly higher than that of hydrochloric acid. © 2023 Central South University of Technology. All rights reserved.

引用

页码：422 / 430

页数：8

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