化学学报 ›› 1962, Vol. 28 ›› Issue (1): 12-19. 上一篇    下一篇

论文

鈧与釷之分离及测定 Ⅰ.以间硝基苯甲酸作试剂

梁树权, 洪水皆   

  1. 中国科学院化学研究所
  • 投稿日期:1960-08-16 发布日期:2013-06-03

ON THE SEPARATION AND DETERMINATION OF SCANDIUM AND THORIUM BY MEANS OF m-NITROBENZOIC ACID

LIANG SHU-CHUAN, HUNG SHUI-CHIEH   

  1. Institute of Chemistry, Academia Sinica
  • Received:1960-08-16 Published:2013-06-03

本文报告用间硝基苯甲酸作钪的沉淀剂,适宜于沉淀的溶液酸度为pH2.5—5.8,沉淀剂之用量以超过理论量一至四倍为宜。曾用于测定1—51毫克氧化钪,均能获得满意之结果。此外尚测定钪盐的热分解曲线,该热解曲线在75—450℃有一平台,经有机元素分析及钪之测定,证明在该温度范围存在的化合物为无水正盐。另在885—1000℃(高于1000℃未测)处有一平台,代表氧化钪之形成。热分解曲线证明此钪沉淀可以其无水正盐作为称衡形式(换算因数为0.12693)。文中尚报告数种阴离子和碱金属盐类之影响,及与其他希土分离的情形,经两次沉淀,轻镧系元素虽多至二百倍,钇多至十倍亦不干扰。同时还设计一分离及分别测定钪和钍的方法。系先在pH1.7两次沉淀钍,再将合并滤液调节至pH2.8—3.0沉淀钪。在ThO2:Sc2O3重量比为1.66:1至19.6:1之分离结果良好,绝对误差在-0.7至+0.5毫克二氧化钍和-0.2至+0.3毫克氧化钪之范围内。

The adsorption of various types of organic surface-active substances in neutral and in alkaline solutions is investigated by measuring the differential capacity at a dropping mercury electrode. It is pointed out that the change of adsorptional behaviour of these substances This communication reports the use of m-nitrobenzoic acid, which has been known as a thorium precipitant, as a reagent for scandium determination and as a means for its separation from thorium. This can be realized by regulating the acidity of test solutions, as thorium precipitates at pH 1.7, and scandium at pH 2.8-3.0 (see Table 1*). By double precipitation of thorium, good separation can be achieved from solutions containing thorium. and scandium oxides in the weight ratio of 1.66:1 to 19.6:1. Absolute errors are -0.7 to +0.5 mg of ThO2 and -0.2 to +0.3 mg of Sc2O3 for 50-200 mg of ThO2 and 10- 15 mg of Sc2O3 mixtures (cf. Table 7 in the Chinese text). A detailed procedure for the separation and determinations of thorium and scandium has been worked out and described. The optimum conditions for using m-nitrobenzoic acid as precipitant for scandium have been studied. Excess precipitant should be one to four times of the theoretical value (see Table 2*). For 1-51 mg of scandium oxide, satisfactory results have been obtained (see Table 3*). The thermal decomposition curve of scandium m-nitrobenzoate (see Fig.1*) has been recorded with a torsion-type thermobalance (Shimadzu Co., Japan). Between 75-450℃, the compound exists as an anhydrous salt, (m-NO2·C6H4·COO)3Sc. Then it decomposes with increasing temperature, and becomes scandium oxide at 885-1000℃. According to the analysis of the dried salt, its formula is deduced as (m-NO2·C6H4·COO)3Sc (Found: C 46.45%,H 2.64% and Sc2O3 12.80%;theoretical: C 46.42%,H 2.23% and Sc2O3 12.69%). After drying to constant weight at 120℃, the anhydrous salt may serve as the weighing form, with a gravimetric conversion factor of 0.12693[Sc2O3/(m-NO2·C6H4·COO)3· Sc] (see Table 4*). The effect of ammonium ion is negligib1e, while alkali metals cause slightly positive errors. However, their effects can be remedied by double precipitation. Owing to the formation of scandium complexes with sulfate and acetate ions, they interfere appreciably (see Table 5*). With double precipitation of scandium m-nitrobenzoate, the presence of up to two hundred times of light lanthanons or ten times of yttrium does not interfere with the scandium determination (see Table 6*).