Three-zone Simulated Moving Bed Process Research Articles

Development of separation method for Alpha-Tocopherol and Gamma-Oryzanol extracted from rice bran oil using Three-Zone simulated moving bed process

• The chromatographic separation method of gamma-oryzanol and alpha-tocopherol was developed. • An environmentally friendly solvent was employed for the separation. • A three-zone simulated moving bed system was designed via process simulation. • The purities of greater than 98% for both compounds were suggested at the optimal condition. • The maximum productivity was obtained at the optimal condition. Gamma-oryzanol and alpha-tocopherol are bio-active compounds that can be found in crude extract of rice bran oil. With superior properties of gamma-oryzanol such as antioxidant activities, anticancer, and antidiabetic, while alpha-tocopherol is one type of vitamin-E, they are both widely used in foods, pharmaceuticals, nutraceuticals, and cosmetic. Therefore, the isolation of these compounds from the crude extract to obtain a single component with high purity is important. In this study, the separation of gamma-oryzanol and alpha-tocopherol using chromatographic method was investigated. The type of mobile phase for C18 column was selected based on the selectivity, back pressure, and toxicity. The adsorption of mono-component was performed to determine the adsorption parameters and the mathematical model for breakthrough curves was developed. The model and the associated parameters were validated by the adsorption experiments using binary mixture. The verified model was used in the design and optimization of three-zone simulated moving bed process. The mobile phase was the mixture of ethanol and water (90 :10 V/V%). At the optimal conditions of the three-zone simulated moving bed, the purity of extract product (rich in gamma-oryzanol), the purity of raffinate product (rich in alpha-tocopherol), and the separation productivity were 99.24%, 98.69% and 29.87 g/L⋅min, respectively.

The Design of Three-Zone Simulated Moving Bed Process for the Separation of Chlorogenic and Gallic Acids Extracted from Spent Coffee Grounds

Spent coffee grounds (SCG) are the agricultural waste generally eliminated by discarding or burning. It contains phenolic compounds with antioxidant properties (such as chlorogenic acid and gallic acid, etc.), which are beneficial in foods, cosmetics and pharmaceuticals. Apart from extraction, the purification of targeted antioxidative substances from the liquid extract is essential. This research presents the separation of chlorogenic and gallic acids using the three-zone simulated moving bed, which is based on the principle of liquid chromatography. Preliminary, SCG were extracted to assess the content of chlorogenic acid and gallic acid. After that, the adsorption behavior of both substances (chlorogenic acid and gallic acid) in a single chromatographic C18 column was studied. The suitable mobile phase was a mixture of acetonitrile, water, and acetic acid (80:20:1). The model simulation was carried out in the mono-component system to determine the adsorption parameters. Breakthrough curve experiments for a binary mixture were performed to validate the predetermined parameters. Then, a three-zone SMB was designed and the model simulation was used to optimize the operating conditions via response surface methodology based on purity and productivity. At the optimal conditions, the purity of chlorogenic acid and gallic acid were 99.27% and 98.43%, respectively.

Relationship between desorbent usage and the recovery of a target product in three-zone simulated moving bed processes designed under the conditions of positive and negative flow-rate-ratios of liquid to solid phases

For a simulated moving bed (SMB) chromatographic process, it has been common knowledge that as desorbent usage increases, the level of separation capability (i.e., the purity and recovery of a target product) continues to improve and then eventually reaches almost a constant level. To check whether there are any exceptional cases concerning such a generally accepted relationship, the effect of desorbent usage on the recovery of a target product under the condition of high purity was investigated using a three-zone SMB process for separation of xylobiose (X2) from a β-xylosidase reaction output. It was found that the considered SMB represented some unusual relationship between desorbent usage and X2 recovery, which also took quite a different pattern according to the searching region for optimal SMB operation parameters. If the optimal operation parameters are determined in the region of positive flow-rate-ratios ("m+ approach"), the use of a larger amount of desorbent than required to make X2 recovery reach a constant level can rather lead to a little reduction in X2 recovery. If the optimal operation parameters are selected in the region of negative flow-rate-ratios ("m− approach"), there exists an optimal desorbent usage, beyond which a further increase in desorbent usage can bring about a significant reduction in X2 recovery. Comparison of the two design approaches reveals that the m− approach can lead to higher X2 recovery and much lower desorbent usage than the m+ approach. Furthermore, such merits of the m− approach over the m+ approach became greater with increasing the SMB throughput.

Continuous-mode separation of fucose and 2,3-butanediol using a three-zone simulated moving bed process and its performance improvement by using partial extract-collection, partial extract-recycle, and partial desorbent-port closing

If a multi-component monosugar mixture including fucose was used as the substrates for the Klebsiella oxytoca fermentation, it could offer the following two benefits simultaneously; (i) the removal of all monosugars other than fucose, and (ii) the acquisition of 2,3-butanediol (BD). To utilize such two benefits in favor of the economical efficiency of the fucose production process, it is essential to accomplish a high-purity separation between fucose and BD on the basis of a highly-economical mode. To address this issue, we aimed to develop a simulated moving bed (SMB) process for continuous-mode separation of fucose and BD with high purities. It was first found that an Amberchrom-CG71C resin could become a suitable adsorbent for the separation of interest. The intrinsic parameters of fucose and BD on such proven adsorbent were determined, and then applied to the optimal design of the fucose-BD separation SMB. The capability of the designed SMB in ensuring high purities and high yields was experimentally verified. Finally, we devised two potential strategies to make a further improvement in product concentrations and/or desorbent usage while keeping the purities and yields of fucose and BD almost unchanged. The first strategy was based on partial extract-collection and partial extract-discard, which was found to result in 33% higher BD product concentration. The second strategy was based on partial extract-collection, partial extract-recycle, and partial desorbent-port closing, which could lead to 25% lower desorbent usage, 33% higher BD product concentration, and 7% higher fucose product concentration.

A simplified strategy to reduce the desorbent consumption and equipment installed in a three-zone simulated moving bed process for the separation of glucose and fructose

The operating strategy of the three-zone simulated moving bed aiming for decreasing the desorbent consumption and the numbers of pump for the separation of glucose and fructose was proposed. Its principle was based on the port-relocation and port-closing/opening technique. The proposed strategy called PR-PCO-NFZIII was the rearrangement of the outlet port such that the raffinate and extract were alternately collected with no flow in zone III during raffinate collecting period. The adsorption model was first verified with experiments in the three-zone simulated moving bed operational mode (TZ-SMB). Then the model was used in the simulation of PR-PCO-NFZIII. The calculated performance parameters of the TZ-SMB, port-relocation, and PR-PCO-NFZIII were compared. The results revealed that PR-PCO-NFZIII outperformed the TZ-SMB mode in terms of solvent consumption, reduced number of pumps, and pressure drop. With this simplified approach, the purities and productivities of both extract and raffinate product were not compromised with adjustable product concentration as a function of extract collecting time to suit the specific demand. Furthermore, with the suitable choice of partial collecting/discarding strategy, the extract and raffinate were greatly concentrated.

Experimental evaluation of the effect of a modified port‐location mode on the performance of a three‐zone simulated moving‐bed process for the separation of valine and isoleucine

The removal of isoleucine from valine has been a key issue in the stage of valine crystallization, which is the final step in the valine production process in industry. To address this issue, a three-zone simulated moving-bed (SMB) process for the separation of valine and isoleucine has been developed previously. However, the previous process, which was based on a classical port-location mode, had some limitations in throughput and valine product concentration. In this study, a three-zone SMB process based on a modified port-location mode was applied to the separation of valine and isoleucine for the purpose of making a marked improvement in throughput and valine product concentration. Computer simulations and a lab-scale process experiment showed that the modified three-zone SMB for valine separation led to >65% higher throughput and >160% higher valine concentration compared to the previous three-zone SMB for the same separation.

Comparison of the relative merits of port-location rearrangement and partial-feeding as the strategy for improving the performances of a three-zone simulated moving chromatography for separation of succinic acid and lactic acid

The three-zone simulated moving bed (SMB) chromatographic process for separation of succinic acid and lactic acid, which has been developed previously, was based on a classical port-location arrangement (desorbent→extract→feed→raffinate) and a classical feeding mode (full-feeding). To improve the performance of the three-zone SMB process, it is worth utilizing the strategy of either a port-location rearrangement (desorbent→feed→raffinate→extract) or a partial-feeding. To investigate which of the two strategies is more effective, the three-zone SMBs based on the port-location rearrangement (PR) and the partial-feeding (PF) were optimized each under equal conditions and then the two strategies were compared in terms of product purities or throughput. The result showed that the PR strategy led to higher purities or higher throughput than the PF strategy in regard to the previously reported three-zone SMB system. To check whether such trend is still valid in other separation systems, the above optimization works were repeated while varying only the selectivity between two feed components. It was confirmed that the PR strategy is definitely superior to the PF strategy. However, such superiority of the PR over the PF strategy is lessened as the selectivity becomes lower. If the selectivity is significantly low, the PR strategy is rather outperformed by the PF strategy.

Development of a three-zone simulated moving bed process based on partial-discard strategy for continuous separation of valine from isoleucine with high purity, high yield, and high product concentration

The issue of separating valine from isoleucine has been a major concern in the biotechnological process for production of valine. To address this issue, an optimal three-zone simulated moving bed (SMB) process for continuous separation of valine was developed in this study. It was first found that an Amberchrom-CG161C resin was highly suitable for the adsorbent of such SMB process. The adsorption isotherm and mass-transfer parameters of valine and isoleucine on the Amberchrom-CG161C adsorbent were then determined through multiple frontal experiments. The determined parameters were used in the next stage of optimizing the SMB for valine separation, which was performed on the basis of genetic algorithm. For the optimized SMB process, a partial-discard strategy was applied to the raffinate port in order to make a further improvement in the valine product concentration. Finally, the optimized SMB based on the partial-discard strategy was tested experimentally using the self-assembled SMB equipment. The experimental results showed that the developed process in this study was highly effective in continuous separation of valine from isoleucine while ensuring the attainment of high product concentration. The experimental data for the SMB effluent histories and the SMB column profiles were also in close agreement with the model predictions.

Continuous separation of succinic acid and lactic acid by using a three-zone simulated moving bed process packed with Amberchrom-CG300C

The issue of separating succinic acid and lactic acid in a continuous mode has been a major concern in the biotechnological process for production of succinic acid. To address this issue, both the optimal design and the experimental validation of a three-zone simulated moving bed (SMB) process for such separation were attempted in this article using the Amberchrom-CG300C resin and a self-assembled SMB unit with three zones. First, the intrinsic parameters of the two organic acids on the Amberchrom-CG300 resin were estimated at 40°C from a series of multiple frontal experiments. The resulting intrinsic parameters were then used in optimizing the experimental setting points for pump flow rates and switching time of the three-zone SMB equipment, which was assisted by an up-to-date genetic algorithm. Based on the optimized conditions, the relevant SMB experiment was conducted at 40°C and all the resultant samples from the product ports and column outlets of the SMB unit were assayed. It was confirmed from the assay results that the continuous separation of succinic acid and lactic acid was performed successfully. The experimental data for the product concentration profiles and the internal concentration profiles were also in reasonable agreement with the model predictions.

Development of a non-triangular separation region for improving the performance of a three-zone simulated moving bed chromatography for binary separation with linear isotherms

For a three-zone simulated moving bed (SMB) chromatography with linear isotherms, the feasible set of operating parameters for complete separation is known to exist within a triangular region of the triangle theory that is formed in the operating parameter plane spanned by the flow-rate-ratios in the separation zones (II and III), which are commonly denoted as m2 and m3. Such an operating region for complete separation region, however, has been established only in the first quadrant (m2, m3) plane, where m2>0 and m3>0, until now. In this study, a new complete-separation region was developed in the third quadrant (m2, m3) plane, where m2<0 and m3<0, regarding a three-zone SMB process for the first time. The results showed that the new separation region created in the third quadrant (m2, m3) plane took a non-triangular shape. The operating parameters within such a non-triangular separation region were capable of guaranteeing complete separation for an ideal system with no mass-transfer effects. For a non-ideal system with considerable mass-transfer effects, the operating parameters that were selected with a sufficient margin from the boundaries of the non-triangular separation region led to high purities. One of the noteworthy features in the pattern of solute migration for such case was that both low-affinity and high-affinity solutes reached their corresponding product ports after taking a turn around the SMB bed once. Finally, it was confirmed from the results of SMB optimization based on genetic algorithm and detailed model that the operating parameters in the third quadrant (m2, m3) plane, if chosen properly, could ensure higher purities or higher throughput than the optimal operating parameters in the first quadrant (m2, m3) plane.

Optimal design and experimental validation of a three-zone simulated moving bed process based on the Amberchrom-CG161C adsorbent for continuous removal of acetic acid from biomass hydrolyzate

In the production process of bio-ethanol from biomass, acetic acid is recognized as the key impurity to be removed from the sugar components that are generated by hydrolyzing biomass. In regard to this issue, it has recently been confirmed that the Amberchrom-CG161C resin was highly qualified as the adsorbent of a simulated moving bed (SMB) process for continuous separation of acetic acid from the biomass hydrolyzate, i.e., sugars. However, the previous study on the Amberchrom-CG161C SMB with the aforementioned separation goal has been limited to only a theoretical work, including some batch-chromatography tests. The experimental validation of such an Amberchrom-CG161C SMB process, including its optimal design, was attempted in this article. This task began by assembling the experimental unit of the SMB process with three zones. Its operating conditions were then optimized by using genetic algorithm. Under the optimized operating conditions, the relevant three-zone SMB experiment was conducted. The assay of all the resultant product samples verified that the SMB separation of interest was performed successfully as designed. The experimental data were also found to agree closely with the model predictions. Finally, a partial-discard strategy was applied to maintain the sugar product concentration as high as possible.

Strategy of rearranging the port locations in a three-zone simulated moving bed chromatography for binary separation with linear isotherms

A three-zone simulated moving bed (SMB) chromatographic process for binary separation, which has been developed previously, was reported to have four ports that are located in the order of desorbent, extract, feed, and raffinate. To make a substantial improvement in the performance of such a three-zone SMB process, the strategy of rearranging the port locations was proposed in this study within a linear isotherm region. The core of the proposed strategy is to transfer the location of the extract port from its classical position (i.e., the position between zones I and II) to the zone III outlet. Simultaneously, the feed and raffinate ports are transferred backwards by one zone. Thus, the order of the proposed port locations follows the order of desorbent, feed, raffinate, and extract. The results from both equilibrium-theory analysis and detailed simulation proved that the proposed strategy was highly effective in improving the product purities or throughput of a three-zone SMB process. Furthermore, it was found that such advantage of the proposed strategy became greater as the difference between the adsorption affinities of the feed components was larger.

Discontinuous and continuous separation of the monomeric and dimeric forms of human bone morphogenetic protein-2 from renaturation batches

Bone morphogenetic protein-2 (BMP-2) is one of the most interesting of the approximately 14 BMPs which belong to the transforming-growth-factor-β (TGF-β) superfamily. BMP-2 induces bone formation and thus plays an important role as a pharmaceutical protein. Recently, rhBMP-2 has been produced in form of inactive inclusion bodies in Escherichia coli. After solubilization and renaturation the biologically active dimeric form of rhBMP-2 can be generated. However, inactive monomers of BMP-2 are also formed during the renaturation process which must be separated from the active dimeric BMP-2. The purpose of this paper is to present: (a) results of an experimental study of a chromatographic separation of the monomeric and dimeric forms; and (b) a concept for a continuous counter-current simulated moving bed (SMB) process. The capacity of heparin as stationary phase was estimated for different salt concentrations in the mobile phase. A simulation study of a three-zone SMB process was performed applying a two step salt gradient. The results reveal the potential of the process for the purification of the dimeric BMP-2.