Pure gold dissolution with hydrogen peroxide as the oxidizer in HBr or HI solution
Pure gold dissolution with hydrogen peroxide as the oxidizer in HBr or HI solution
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DOI：
10.1016/j.molliq.2017.09.080
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发表时间：
2017-11-01
影响因子：
6
通讯作者：
Okamura, Kei
中科院分区：
文献类型：
--
作者：
Hojo, Masashi;Iwasaki, Shunsuke;Okamura, Kei
在35℃条件下，以H2O2为氧化剂，在HBr或HI存在下，以含NaCI的稀HNO3体系为对照，探索了纯金的溶解。在20 mL反应容器中，0.02 ~ 0.2 mol dm(-3) H2O2溶液和0.2 ~ 2.0 mol dm(-3) HBr为纯金丝（99.95%，直径0.25 mm，约20 mg）提供了有效的溶解介质，溶解速率常数log （k/s(-1)）随H2O2和HBr浓度的增加从-6.17增加到-3.33。“无关”盐或辅助电解质，LiCO4， NaClO4或Mg(ClO4)(2)对对数（k/s(-1)）值的影响非常小。相反，在含有2.0 mol dm(-3) nacl的2.0 mol dm(-3) HNO3溶液中（作为氧化剂），在50℃下，log （k/s(-1)）值为-4.22，随着电解质浓度的增加，log (k/s(-1)) = 0.66（约4.5倍）。添加电解质的效果依次增大，NaClO4类似于LiClO4 < Mg(ClO4)(2)。在酸性介质中，H2O2具有天然的强氧化力，而稀HNO3 (
The pure gold dissolution has been explored for H2O2 as the oxidizer in the presence of HBr or HI at 35 degrees C and, as the reference, for the dilute HNO3 system containing NaCI. It has been found that 0.02-0.2 mol dm(-3) H2O2 solutions with 0.2-2.0 mol dm(-3) HBr have provided effective media for dissolution of pure gold-wire (99.95%, 0.25 mm diameter, ca. 20 mg) in a 20 mL reaction vessel: the dissolution rate constant, log (k/s(-1)), has increased from -6.17 to -3.33 with increasing concentrations of H2O2 and HBr. The influences of "indifferent" salts or supporting electrolytes, LiCO4, NaClO4, or Mg(ClO4)(2) on the log (k/s(-1)) value have been very small. Contrastingly, the log (k/s(-1)) value of -4.22 in 2.0 mol dm(-3) HNO3 (as the oxidizer) solution containing 2.0 mol dm(-3) NaCI at 50 degrees C has been accelerated remarkably with increasing electrolyte concentrations, e.g., Delta log (k/s(-1)) = 0.66 (ca. 4.5 times) at 1.0 mol dm(-3) Mg(ClO4)(2). The effect of the added electrolytes increases in the order, NaClO4 similar to LiClO4 < Mg(ClO4)(2). In acidic media, H2O2 has naturally strong oxidizing power while dilute HNO3 (