Abstract: pH measurement was adopted to obtain the absorption rate of CO₂. Liquid composition was correlated to the dynamic change of pH. Piecewise fitting was further used on liquid composition to obtain the CO₂ absorption rate. Therefore, the liquid composition on the absorption rate of CO₂ was then achieved. For low concentration sodium hydroxide, the absorption rate of CO₂ does not change until CO₂ physical absorbed into NaHCO₃. While for high concentration NaOH, CO₂ absorption rate decreases when NaOH is fully converted to Na₂CO₃. However, within the two stages of absorption, CO₂ absorption rate does not change. When CO₂ is absorbed into NaHCO₃, CO₂ absorption rate decreases with the increase of saturation state for the solution. As for CO₂ absorption into NaOH, both CO₂ and sodium concentration promote the absorption, with more influence by sodium concentration; For CO₂ absorption into Na₂CO₃, the absorption rate does not increase when the concentration of Na₂CO₃ is higher 0.05mol/L; For CO₂ absorption into NaHCO₃, low concentration NaHCO₃ promotes the absorption of CO₂ while high concentration of NaHCO₃ inhibits CO₂ absorption due to salt-out effect. To reduce CO₂ absorption into solutions, high concentration of NaHCO₃ larger than 0.5mol/L is preferable.

Key words: carbon dioxide, absorption, chemical kinetics, model

摘要： 采用基于pH测量的CO₂吸收速率研究方法。将pH与溶液中的成分相关联，采用分段拟合获得CO₂吸收速率，获得溶液成分对吸收速率的影响规律。对于低浓度的NaOH来说，吸收速率一直保持不变直到CO₂物理吸收到NaHCO₃溶液中。对于高浓度的NaOH，NaOH完全转化成Na₂CO₃时，吸收速率降低。但在两个吸收阶段中，吸收速率不变，CO₂物理吸收到NaHCO₃中时，吸收速率随CO₂饱和度的增加而降低。对CO₂吸收到NaOH中，CO₂和钠离子浓度都促进吸收，钠离子浓度影响更大；对于CO₂吸收到Na₂CO₃中，当Na₂CO₃浓度大于0.05mol/L，吸收速率不随浓度增加；对于CO₂吸收到NaHCO₃中，低浓度的钠可以促进CO₂吸收，而高浓度的钠抑制CO₂吸收，这主要由于析盐的作用。为避免CO₂大量吸收，优先选择0.5mol/L以上浓度的NaHCO₃。

关键词: 二氧化碳, 吸收, 反应动力学, 模型