草酸钙酸分解的热力学分析  

Thermodynamic analysis on decomposition of calcium oxalate with acid

作　　者：曹才放[1,2] 彭紫云 卢含 吕亚航 傅爱林 CAO Caifang;PENG Ziyun;LU Han;Lü Yahang;FU Ailin(Division of Materials Metallurgy and Chemistry,Jiangxi University of Science and Technology,Ganzhou 341000,China;Fujian Changting Golden Dragon Rare-earth Co.Ltd.,Longyan 366300,China)

机构地区：[1]江西理工大学材料冶金化学学部,江西赣州341000 [2]福建省长汀金龙稀土有限公司,福建龙岩366300

出　　处：《中南大学学报（自然科学版）》2023年第2期422-430,共9页Journal of Central South University:Science and Technology

基　　金：江西省重点研发计划重点项目(20192ACB70017)。

摘　　要：为阐明草酸钙渣酸分解过程的热力学,基于同时平衡原理、质量守恒原理、电中性原则,以盐酸和硫酸为分解药剂,计算和绘制草酸钙酸分解的热力学平衡图,并结合实验验证。研究结果表明:单因素实验结果与热力学计算结果的趋势一致,且部分情况的实验值和计算值吻合;草酸钙是较稳定的沉淀,在pH=4~13的范围内,维持较低溶解水平;在盐酸体系中,氯化钙和草酸对草酸钙的溶解有显著抑制作用,而在硫酸体系中,硫酸钙的生成使溶液钙浓度维持在较低水平,从而促进草酸钙的分解;硫酸参与草酸钙分解的反应率随初始酸度增加而增加,硫酸浓度为4 mol/L时,硫酸的反应率可达39.7%;而盐酸的反应率几乎不受初始酸度的影响,维持在5.4%的较低水平。此外,硫酸参与草酸钙分解的反应率随初始草酸浓度增加而下降,但在相同初始草酸浓度下,硫酸参与草酸钙分解的反应率明显比盐酸的高。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.

关 键 词：草酸钙 盐酸 硫酸 分解 热力学 

分 类 号：TF09[冶金工程—冶金物理化学]