Carboxyl groups and ion exchange in low-rank coals
Carboxyl groups and ion exchange in low-rank coals
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DOI：
10.1016/0016-2361(70)90040-2
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发表时间：
1970-04
期刊：
影响因子：
7.4
通讯作者：
H. Schafer
中科院分区：
文献类型：
--
作者：
H. Schafer
本文研究了低阶煤的离子交换性质，以期获得在酚基存在下测定羧基的最佳条件。研究了pH值、温度和气氛对交换的影响。评估了初始交换后估计羧基含量的替代程序，例如滴定释放的酸，估计交换煤中的阳离子和反交换中消耗的酸。得出的结论是，在pH 8.25下回流（单次4 h），然后在煤的存在下电位滴定至pH 8.25的乙酸钡交换提供了最可靠的方法。没有获得证据支持文献中的建议，即与二价阳离子（例如Ca++、Ba++）的乙酸酯交换可导致形成半盐，其中一个阳离子原子仅与一个羧基缔合。
The ion-exchange properties of low-rank coals have been studied with a view to obtaining optimum conditions for the determination of carboxyl groups in the presence of phenolic groups. The effect of pH, temperature, and atmosphere on the exchange has been examined. Alternative procedures for estimating the carboxyl content following the initial exchange were assessed, eg titration of acid released, estimation of cation in the exchanged coal and of acid consumed in the back-exchange. It was concluded that exchange with barium acetate at pH 8.25 under reflux (single for 4 h) followed by potentiometric titration to pH 8.25 in the presence of the coal provided the most reliable approach. No evidence was obtained to support suggestions in the literature that exchange with the acetate of a bivalent cation (eg Ca++, Ba++) can lead to formation of the half salt where one atom of cation is associated with only one carboxyl group.