Adsorption and Desorption Behavior of Ectoine Using Dowex® HCR-S Ion-Exchange Resin

Abstract

Dowex® HCR-S ion-exchange resin was used to adsorb ectoine in a batch system under varying operation conditions in terms of contact time, temperature, pH value, initial concentration of ectoine, and type of salt. Six adsorption isotherm models (Langmuir, Freundlich, Temkin, Dubinin–Radushkevich, Sips, and Redlich–Peterson) and three kinetic models (pseudo-first-order, pseudo-second-order, and intraparticle diffusion) were used to investigate the ectoine adsorption mechanism of ion-exchange resin. According to the experimental results, the mechanism of ectoine adsorption using an ion exchanger includes the ion-exchange reaction and physisorption. Both the Langmuir and Freundlich models were found to have a high fitting. For the kinetic analysis, the pseudo-second-order and intraparticle diffusion models were suitable to describe the ectoine adsorption. Dowex® HCR-S resin has an average saturated adsorption capacity of 0.57 g/g and 93.6% of ectoine adsorption at 25~65 °C, with an initial concentration of 125 g/L. By changing the pH of the environment using NaOH solution, the adsorbed ectoine on the ion-exchange resin can be desorbed to 87.7%.

Thermodynamic and Kinetic Equilibrium for Adsorption of Cellulosic Xylose of Commercial Cation-Exchange Resins

“…Another adsorption isotherm model is Temkin isotherm, which is the model used to describe the interaction between adsorbent–adsorbate. The Temkin model indicates a linear decrease in energy adsorption with surface coverage and considers the interaction between the adsorbate and adsorbent. , The Temkin isotherm model is defined as eq q e = RT b normalT ln nobreak0em0.25em⁡ A T + ( RT b T ) ln nobreak0em0.25em⁡ C e …”

“…Moreover, the kinetic behavior of adsorbates on adsorbents has been studied using the effect of time on the adsorption process. In this study, Lagergren’s pseudo-first order and pseudo-second-order models were applied as adsorption reaction models to investigate the adsorption kinetic behavior of xylose onto both commercial resins including Amberlite IR120 and Indion 225. , The adsorption reaction models typically revealed the rate of adsorbate uptake by adsorbents, but they do not indicate the actual cause of adsorption. The equation for Lagergren’s pseudo-first order kinetics is as follows eq ln ( q normale − q t ) = ln nobreak0em0.25em⁡ q e − k 1 t …”

“…Adsorption isotherm is crucial information for understanding how adsorbate interacts with the adsorbent during adsorption. In this study, three commonly used isotherm models, namely, Langmuir, Freundlich, and Temkin, were applied to evaluate the equilibrium data of adsorption for xylose onto two different CER at 15, 25, 35, and 45 °C. ,− …”

“…In this study, three commonly used isotherm models, namely, Langmuir, Freundlich, and Temkin, were applied to evaluate the equilibrium data of adsorption for xylose onto two different CER at 15, 25, 35, and 45 °C. 16 , 43 − 45 …”

The kinetics of heparin adsorption with Dowex 1x1 ion exchange resin

“…In the case of adsorption kinetics of heparin onto the zeolite imidazolate framework-8 (Abdolmaleki et al, 2022) or ectoine onto the Dowex HCR-S (Wu et al, 2021), it was described by the pseudo-second-order model better than the pseudo-firstorder model.…”