CFD Simulations of Microreactors for the Hydrolysis of Cellobiose to Glucose by β-Glucosidase Enzyme.

Virginia Venezia,Valeria Califano,Giulio Pota,Almerinda Di Benedetto,Gianluca Landi,Aniello Costantini

doi:10.3390/mi11090790

Abstract

The enzymatic hydrolysis of lignocellulosic biomass-derived compounds represents a valid strategy to reduce the dependence on fossil fuels, with geopolitical and environmental benefits. In particular, β-glucosidase (BG) enzyme is the bottleneck in the degradation of cellulose because it catalyzes the hydrolysis of cellobiose, a known inhibitor of the other cellulolytic enzymes. However, free enzymes are unstable, expensive and difficult to recover. For this reason, the immobilization of BG on a suitable support is crucial to improve its catalytic performance. In this paper, computational fluid dynamics (CFD) simulations were performed to test the hydrolysis reaction in a monolith channel coated by BG adsorbed on a wrinkled silica nanoparticles (WSNs) washcoat. We initially defined the physical properties of the mixture, the parameters related to kinetics and mass transfers and the initial and boundary conditions thanks to our preliminary experimental tests. Numerical simulation results have shown great similarity with the experimental ones, demonstrating the validity of this model. Following this, it was possible to explore in real time the behavior of the system, varying other specified parameters (i.e., the mixture inlet velocity or the enzymatic load on the reactor surface) without carrying out other experimental analyses.

Highlights

The exhaustion of fossil fuels and environmental pollution, due to the global phenomena of atmospheric degradation, led to a search for alternative, eco-sustainable and renewable energy sources such as biofuels
Lignocellulosic biomass has been considered a source of strategic fuel because it does not compete with food crops and it is abundant in vegetation
The main component of lignocellulosic biomass is cellulose, a polymer composed of glucose molecules which can be hydrolyzed into fermentable glucose [2]

Summary

Introduction

The exhaustion of fossil fuels and environmental pollution, due to the global phenomena of atmospheric degradation (i.e., greenhouse effect, acid rains, ozone hole), led to a search for alternative, eco-sustainable and renewable energy sources such as biofuels. We realized the intensification and the engineering of the enzymatic hydrolysis process through the transition from a batch reactor to a plug-flow microreactor by the application of ceramic cordierite monoliths whose washcoat consisted of β-glucosidase immobilized into a mesoporous silica nanoparticle support [18].This inorganic matrix can be used for many applications such as drug delivery and fluorescence biological probes and can be an efficient support for enzyme adsorption [19,20,21,22]. In order to properly design the microreactor and to optimize the performance, full investigations of the role of the operating conditions are required In this context, mathematical modeling plays a crucial role in the development and design of chemical (micro) reactors. The model results will support the experimental activity to optimize the IEMs operation

Model Description

Effect of Mixture Inlet Velocity

Findings

Conclusions