Key Laboratory of Industrial Microbiology, Ministry of Education & Tianjin City, College of Biotechnology, Tianjin University of Science and Technology, Tianjin, People's Republic of China.
PLoS One. 2010 Nov 11;5(11):e13948. doi: 10.1371/journal.pone.0013948.
The polyacrylic resin Amberlite IRA-67 is a promising adsorbent for lactic acid extraction from aqueous solution, but little systematic research has been devoted to the separation efficiency of lactic acid under different operating conditions.
METHODOLOGY/PRINCIPAL FINDINGS: In this paper, we investigated the effects of temperature, resin dose and lactic acid loading concentration on the adsorption of lactic acid by Amberlite IRA-67 in batch kinetic experiments. The obtained kinetic data followed the pseudo-second order model well and both the equilibrium and ultimate adsorption slightly decreased with the increase of the temperature at 293-323K and 42.5 g/liter lactic acid loading concentration. The adsorption was a chemically heterogeneous process with a mean free energy value of 12.18 kJ/mol. According to the Boyd(_)plot, the lactic acid uptake process was primarily found to be an intraparticle diffusion at a lower concentration (<50 g/liter) but a film diffusion at a higher concentration (>70 g/liter). The values of effective diffusion coefficient D(i) increased with temperature. By using our Equation (21), the negative values of ΔG° and ΔH° revealed that the adsorption process was spontaneous and exothermic. Moreover, the negative value of ΔS° reflected the decrease of solid-liquid interface randomness at the solid-liquid interface when adsorbing lactic acid on IRA-67.
CONCLUSIONS/SIGNIFICANCE: With the weakly basic resin IRA-67, in situ product removal of lactic acid can be accomplished especially from an open and thermophilic fermentation system without sterilization.
聚丙烯酸树脂 Amberlite IRA-67 是一种从水溶液中提取乳酸的有前途的吸附剂，但对于不同操作条件下乳酸的分离效率，很少有系统的研究。
方法/主要发现：在本文中，我们通过批处理动力学实验研究了温度、树脂剂量和乳酸装载浓度对 Amberlite IRA-67 吸附乳酸的影响。所得动力学数据很好地遵循伪二阶模型，并且在 293-323K 和 42.5g/l 乳酸装载浓度下，平衡和最终吸附都随着温度的升高而略有下降。吸附是一个化学非均相过程，平均自由能值为 12.18kJ/mol。根据 Boyd（_）图，在较低浓度（<50g/l）下，乳酸摄取过程主要是内扩散，但在较高浓度（>70g/l）下是膜扩散。有效扩散系数 D(i)的值随温度升高而增加。通过使用我们的方程（21），ΔG°和ΔH°的负值表明吸附过程是自发的和放热的。此外，ΔS°的负值反映了在 IRA-67 上吸附乳酸时固-液界面上固体-液体界面无序性的降低。
结论/意义：使用弱碱性树脂 IRA-67，可以在不灭菌的情况下从开放式和嗜热发酵系统中完成原位去除乳酸。
