Countercurrent exchange

About: Countercurrent exchange is a research topic. Over the lifetime, 2255 publications have been published within this topic receiving 28687 citations. The topic is also known as: Countercurrent exchange.

Multistage continuous countercurrent diafiltration for formulation of monoclonal antibodies

Abstract: There is growing interest in the development of fully integrated and continuous biomanufacturing processes for the production of monoclonal antibody products. A recent study has demonstrated the feasibility of using a two-stage countercurrent diafiltration (DF) process for continuous product formulation, but this system did not provide sufficient levels of buffer exchange for most applications. The objective of this study was to design and test a three-stage countercurrent DF system that could achieve at least 99.9% buffer exchange over 24 hr of continuous operation. Experimental data were obtained using concentrated solutions of human immunoglobulin G as a model protein, with the extent of vitamin B12 removal used to track the extent of DF. Pall Cadence™ inline concentrators with Delta 30 kD regenerated cellulose membranes were used in the three stages to achieve high conversion in a single pass. The three-stage system showed stable operation with >99.9% vitamin B12 removal and a minimal increase in pressure over the full 24 hr. Modules were effectively cleaned using sodium hydroxide, with nearly complete recovery of water permeability. A simple economic analysis was presented that accounts for the trade-offs between quantity of buffer used and membrane costs for this type of countercurrent staged DF process. The results provide important insights to the design and operation of a continuous process for antibody formulation.

[16] Countercurrent distribution

Abstract: Publisher Summary Countercurrent distribution is a method for the separation of protein subunits that offers the possibility of using conditions that cannot be achieved with separation methods such as electrophoresis or ion-exchange chromatography. Many proteins lose biological activity when exposed to the solvent systems used for countercurrent distribution. To carry out countercurrent distribution on any substance, a two phase system must be found in which the substance is soluble to approximately the same extent in both phases. Due to the insolubility of most proteins in organic solvents, many solvent systems proved useful for the separation of small organic molecules cannot be used for proteins. Difficulty is frequently encountered in attempting to dissolve large quantities of protein in the system directly. However, the dry protein is frequently soluble in the organic phase of these systems and can be dissolved directly. There are several methods of dealing with emulsions that form when a protein is dissolved in a two-phase system. The formation of emulsions is frequently due to the presence of small amounts of insoluble protein that collect at the interface of the two phases. The distribution pattern with sufficient detail can be obtained if tubes spaced at intervals approximately equal to one half the square root of the number of transfers are analyzed. The operation of the countercurrent machine and recovery of distributed material are also discussed.

Dynamic model of a countercurrent packed column operating at high pressure conditions

Abstract: A dynamic simulation model of a countercurrent packed column operating at supercritical fluid (SCF) conditions is presented. The model was developed and applied to a case study involving the fractionation of a binary mixture of squalene and methyl oleate using supercritical carbon dioxide. The purpose of the separation process is to remove the methyl oleate from the solution and concentrate squalene in the raffinate phase. The final model comprises the differential material balances in the packed column and algebraic equations describing the thermodynamic phase equilibrium, mass transfer and the hydrodynamics of the two countercurrent phases. The model was validated by carrying out a series of experiments in a lab-scale continuous SCF extraction unit. A good agreement was obtained between measured and predicted composition profile of the outlet streams over time.

Modeling study of silica membrane performance for hydrogen separation

Abstract: The main aim of this work is the presentation of quantitative analysis of silica membrane for hydrogen separation from methanol steam reforming products to produce high purity hydrogen This study uses a single stage silica membrane in three different flow patterns, namely cocurrent, countercurrent and cross flow, for separation of a typical methanol steam reforming products stream The modeling results showed that the silica membrane presents noticeable performance to produce high purity hydrogen In particular, by considering the stage cut, it was found that the hydrogen molar fraction in the permeate side was decreased by increasing the stage cut from 01 to 065, whereas the carbon monoxide molar fraction increased for all of the flow patterns In addition, a similar effect was observed for membrane surface area Moreover, the retentate side pressure effect was positive on the silica membrane performance, although the improvement of silica membrane performance was not considerable for more than a pressure gradient of 3 bar This analysis indicated that by using single stage silica membrane, 99% hydrogen molar fraction and 04% carbon monoxide molar fraction in the permeate side can be achieved for a pressure gradient equal to 3 bar © 2015 Curtin University of Technology and John Wiley & Sons, Ltd