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Acid Dissociation Constant (pKa) of Common Monoethylene Glycol (MEG) Regeneration Organic Acids and Methyldiethanolamine at Varying MEG Concentration, Temperature, and Ionic Strength
Journal of Chemical & Engineering Data ( IF 2.0 ) Pub Date : 2018-06-25 , DOI: 10.1021/acs.jced.8b00221
Adam Soames 1 , Stefan Iglauer 2 , Ahmed Barifcani 1 , Rolf Gubner 1
Affiliation  

The acid dissociation constants (pKa) of four organic acids (formic, acetic, propanoic, and butanoic) commonly found in monoethylene glycol (MEG) regeneration systems and methyldiethanolamine (MDEA) were measured via potentiometric titration. Dissociation constants were measured within varying concentration of MEG solution (0, 30, 40, 50, 60, 70, and 80 wt %) and at varying temperature (25, 30, 40, 50, 60, 70, and 80 °C). Thermodynamic properties of the dissociation process including Gibbs free energy (ΔG° kJ mol–1), standard enthalpy (ΔH° kJ mol–1), and entropy (ΔS° kJ mol–1 K–1) were calculated at 25 °C using the van’t Hoff equation. Comparison of the reported experimental pKa values and calculated thermodynamic properties in aqueous solution to the literature demonstrated good agreement. Two models have been proposed to calculate the pKa of acetic acid and MDEA within MEG solutions of varying concentration, temperature, and ionic strength. The proposed models have an average error of 0.413% and 0.265% for acetic acid and MDEA, respectively.

中文翻译:

在不同的MEG浓度,温度和离子强度下,普通单乙二醇(MEG)再生有机酸和甲基二乙醇胺的酸解离常数(p K a

通过电位滴定法测量了单乙二醇(MEG)再生系统和甲基二乙醇胺(MDEA)中常见的四种有机酸(甲酸,乙酸,丙酸和丁酸)的酸解离常数(p K a)。在不同浓度的MEG溶液(0、30、40、50、60、70和80 wt%)和变化的温度(25、30、40、50、60、70和80°C)下测量离解常数。离解过程的热力学性质包括吉布斯自由能(ΔG °kJ mol –1),标准焓(ΔH °kJ mol –1)和熵(ΔS °kJ mol –1 K –1))是使用van't Hoff方程在25°C下计算的。与文献报道的实验p K a值和在水溶液中计算的热力学性质的比较与文献证明了很好的一致性。已经提出了两个模型来计算浓度,温度和离子强度变化的MEG溶液中乙酸和MDEA的p K a。所提出的模型对于乙酸和MDEA的平均误差分别为0.413%和0.265%。
更新日期:2018-06-27
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