The present study evaluates the capability of ion exclusion chromatography (IEC) of short chain aliphatic carboxylic acids using a cation exchange column (8% sulfonated cross-linked styrene-divinylbenzene copolymer) in different experimental conditions. Since one of the prerequisites to the development of an efficient carboxylic acid separation process is to obtain the optimum operational conditions, response surface methodology (RSM) was used to develop an approach to evaluate carboxylic acids separation process in IEC columns. The effect of the operating conditions such as column temperature, sulfuric acid concentration as the mobile phase, and the flow rate was studied using Central Composite Face (CCF) design. The optimum operating conditions for the separate injection of lactic acid and acetic acid is temperature of 75 °C, sulfuric acid concentration of 0.003 N for both acids and flow rate of 0.916 (0.886) mL/min for acetic acid (lactic acid). Likewise, the optimum conditions for the simultaneous injection of acetic and lactic acid mixture are the column temperature of 68 °C, sulfuric acid concentration of 0.0003 N, and flow rate of 0.777 mL/min. In the next step, the adsorption equilibria of acetic acid and lactic acid on the stationary phase were investigated through a series of Frontal Analysis (FA), Frontal Analysis by Characteristic Points (FACP), and using Langmuir isotherm model. The results showed an excellent agreement between the model and experimental data. Finally, the results of thermodynamic studies proved that the IEC process for separation of acetic and lactic acid is a spontaneous, feasible, exothermic, and random process with a physical adsorption mechanism.

The results of the current paper can be a valuable information in the stages of designing IEC columns for separation of aliphatic carboxylic acids.

本研究评估在不同的实验条件下使用阳离子交换柱（8％磺化交联的苯乙烯-二乙烯基苯共聚物）进行短链脂族羧酸的离子排阻色谱（IEC）的能力。由于开发有效的羧酸分离方法的先决条件之一是获得最佳的操作条件，因此使用响应面方法（RSM）来开发一种评估IEC色谱柱中羧酸分离过程的方法。使用中央复合端面（CCF）设计研究了色谱柱温度，硫酸浓度作为流动相和流速等操作条件的影响。分别注入乳酸和乙酸的最佳操作条件是温度为75°C，两种酸的硫酸浓度均为0.003 N，乙酸（乳酸）的流速为0.916（0.886）mL / min。同样，同时注入乙酸和乳酸混合物的最佳条件是色谱柱温度为68°C，硫酸浓度为0.0003 N，流速为0.777 mL / min。下一步，通过一系列前沿分析（FA），特征点前沿分析（FACP）并使用Langmuir等温线模型研究了乙酸和乳酸在固定相上的吸附平衡。结果表明模型与实验数据之间有很好的一致性。最后，热力学研究的结果证明，IEC分离乙酸和乳酸的过程是自发的，可行的，放热的，

本文的结果可以为设计用于分离脂肪族羧酸的IEC色谱柱的阶段提供有价值的信息。