Estimates of the second dissociation constant of H2S from the surface sulfidation of crystalline sulfur
Estimates of the second dissociation constant of H2S from the surface sulfidation of crystalline sulfur
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DOI：
10.1016/s0016-7037(01)00896-1
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发表时间：
2002-05-01
影响因子：
5
通讯作者：
Alekhin, YV
中科院分区：
文献类型：
--
作者：
Migdisov, AA;Williams-Jones, AE;Alekhin, YV
在温度为 25、50 和 70℃、氯化钠浓度为 0.1 和 0.5 mol/dm(-3)、log C-H(+) 值在 -2.3 至 -5 范围内的含 H,S 溶液中，实验研究了硫化氢 (Gamma(H2)S) 和质子 (Gamma(H)(+)) 在晶体硫表面上的吸附。在所有温度下。硫表面的主要过程是去质子化，Gamma(H2)S 的平均值非常接近 Gamma(H)(+) 测定的最高值。这一发现，再加上无 H2S 溶液中缺乏可检测到的质子吸附，表明硫表面上的质子吸附/解吸是通过在 H2S 存在下形成等效的 S - H2S 络合物而发生的。我们认为，这种络合代表了硫表面的硫化，这是一个类似于氧化物表面羟基化的过程，并且硫化可以 可以通过以下反应描述： 相当于 S + H2S = 相当于 SSH(2)(0) beta 度 相当于 SH 度复合物的去质子化通过以下反应发生： 相当于 SSH 度 = 相当于 SSH(-) + H+ beta-在 -log beta(-) 下获得的值为 2.9、2.8 和 2.9 (+/-0.23) 分别为 25、50 和 70 摄氏度。这些数据用于使用 Schoonen 和 Barnes (1988) 提出的外推法估计水溶液中硫化氢的第二解离常数，并分别得出相应的常数值：17.4 +/- 0.3、15.7 和 14.5。 25°C 的值与 Giggenbach (1971) 的实验测定值 17 +/- 0.1 非常一致；迈耶等人。 (1983) 17 +/- 1； Licht 和 Manassen (1987) 为 17.6 +/- 0.3；和利希特等人。 (1990) 17.1 +/- 0.3。版权所有 (C) 2002 爱思唯尔科学有限公司
The adsorption of hydrogen sulfide (Gamma(H2)S) and protons (Gamma(H)(+)) on the surface of crystalline sulfur was investigated experimentally in H,S-bearing solutions at temperatures of 25, 50, and 70degreesC, NaCl concentrations of 0.1 and 0.5 mol/dm(-3) and log C-H(+) values in the range -2.3 to -5. At all temperatures. the dominant process on the surface of the sulfur was deprotonation, and the average values of Gamma(H2)S were very close to the highest values determined for Gamma(H)(+). This finding, combined with the lack of detectable proton adsorption in H2S-free solutions, suggests that proton adsorption/desorption on the surface of sulfur occurs through formation of equivalent toS - H2S complexes in the presence of H2S.We propose that this complexation represents sulfidation of the sulfur surface, a process analogous to hydroxylation of oxide surfaces, and that the sulfidation can be described by the reaction:equivalent toS + H2S = equivalent toSSH(2)(0) betadegreesThe deprotonation of the equivalent to SHdegrees complex occurs via the reaction:equivalent to SSHdegrees = equivalent toSSH(-) + H+ beta-Values of 2.9, 2.8, and 2.9 (+/-0.23) were obtained for -log beta(-) at 25, 50, and 70degreesC, respectively. These data were employed to estimate the second dissociation constant for hydrogen sulfide in aqueous solutions using the extrapolation method proposed by Schoonen and Barnes (1988) and yielded corresponding values for the constant of 17.4 +/- 0.3, 15.7, and 14.5, respectively. The value for 25degreesC is in very good agreement with the experimentally determined values of Giggenbach (1971) at 17 +/- 0.1; Meyer et al. (1983) at 17 +/- 1; Licht and Manassen (1987) at 17.6 +/- 0.3; and Licht et al. (1990) at 17.1 +/- 0.3. Copyright (C) 2002 Elsevier Science Ltd.