Temperature Dependence of Henry’s Law Constant for Hydrogen Cyanide. Generation of Trace Standard Gaseous Hydrogen Cyanide

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• 作者：Jian Ma ; Purnendu K. Dasgupta ; William Blackledge ; Gerry R. Boss
• 刊名：Environmental Science & Technology
• 出版年：2010
• 出版时间：April 15, 2010
• 年：2010
• 卷：44
• 期：8
• 页码：3028-3034
• 全文大小：256K
• 年卷期：v.44,no.8(April 15, 2010)
• ISSN：1520-5851

文摘

Primary data for the temperature dependent solubility of HCN in water do not presently exist for low concentrations of HCN at environmentally or physiologically relevant temperatures. Henry’s Law constant (K_H, M/atm) for the vapor−solution equilibrium of HCN was determined in 0.1 M sodium phosphate buffer (adjusted to pH 9.00 ± 0.03 at 296.6 ± 0.1 K) from 287−311 K. Stable gas phase concentrations of HCN are generated by established techniques, via air equilibration of aqueous cyanide partitioned by a microporous membrane. The effluent gaseous HCN, in equilibrium with the constant temperature aqueous cyanide, was collected in dilute NaOH and determined by a spectrophotometrically using cobinamide. The K_H of HCN may be expressed as ln K_H (M/atm) = (8205.7 ± 341.9)/T − (25.323 ± 1.144); r² = 0.9914) where T is the absolute temperature in K. This corresponds to 9.02 and 3.00 M/atm at 25 and 37.4 °C, respectively, compared to actual measurements of 9.86 and 3.22 at 25.0 and 37.8 °C, respectively. The technique also allows for convenient generation of trace levels of HCN at ppbv-ppmv levels that can be further diluted.