(453d) Mathematical Modeling and Simulation of a Bijel Membrane Reactor

Keywords: Biphasic Enzyme Membrane Reactor, Bijel Membrane, Process Intensification

A membrane reactor is a reactor integrated with a separator leading to energy savings and reduced plant volume [1, 2]. On the other hand, enzymatic bioconversion processes have shown great potential in transforming raw materials into valuable products and in decomposing toxic materials and can be used in the pharmaceutical, food, waste treatment, and biotechnology-based industries [3]. Thus, performing enzymatic reactions in membrane reactors offers several benefits. The basic idea in an enzyme membrane reactor is the immobilization of enzyme(s) in the sponge layer of the membrane [4-6]. The main issue in biphasic membrane reactors is that as the thickness of the sponge layer increases, because of the diffusion resistance and the deformation of the molecular structure, some losses in the activity of the enzyme can occur [4]. One way to address this issue is to use a bijel medium.

A bijel is a biphasic medium made up of co-continuous domains of an oily and an aqueous phase in the form of intertwined microchannel arrangements formed with rigid walls of a jammed layer of colloidal particles at their interface. A bijel medium provides a robust and rigid micro-interface between two co-continuous immiscible phases. Because of these characteristics, of bijels are good reaction media for biphasic reactions. A major concern is the feasibility and reliability of bijel fabrication. Recent studies on the robust fabrication of bijel membranes based on solvent transfer-induced separation have been promising [7-11]. In a bijel membrane reactor, a bijel medium is used as the reacting medium instead of a sponge layer of a membrane in a membrane reactor. As a result, a co-continuous flow of reactants and products in the reacting region forms leading to prevent from product inhibition and loss of enzyme activity that occur in conventional membrane reactors. Although the area of mathematical modeling of membrane reactors is mature, there has been no reported study of the mathematical modeling of bijel membrane reactors.

In this work, we present a study on the mathematical modeling and simulation of a bijel membrane reactor. The key features of a bijel membrane reactor are described first. A general physicochemical macroscopic-scale mathematical model of the reactor is then derived and presented. Appropriate boundary conditions for the system are proposed. As a specific case, a hollow-fiber membrane reactor that has been used for the hydrolysis of oleuropein with immobilized β-glucosidase enzymes [12], is considered to evaluate the performance of the developed reactor model. A solution method that has been developed for solving the resulting mathematical equations using the control volume approach is presented. Parameter estimation is performed to estimate unknown parameters. Finally, the model is validated by comparing the model predictions with measurements. Based on the validated model, the effect of different parameters on the bijel membrane reactor has been studied. As the bijel membrane reactor technology is at its infancy, developing a mathematical model and providing a suitable solution method for solving the model equations are timely. The mathematical model can have applications in the scale-up, design, and optimization of bijel membrane reactors.

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