Preliminary Study on Enzymatic-Based Cleaning of Cation-Exchange Membranes Used in Electrodialysis System in Red Wine Production.

Bdiri Bdiri,Bensghaier Bensghaier,Baklouti Baklouti,Chaabane Chaabane,Larchet Larchet,Kozmai Kozmai

doi:10.3390/membranes9090114

Abstract

The use of enzymatic agents as biological solutions for cleaning ion-exchange membranes fouled by organic compounds during electrodialysis (ED) treatments in the food industry could be an interesting alternative to chemical cleanings implemented at an industrial scale. This paper is focused on testing the cleaning efficiency of three enzyme classes (β-glucanase, protease, and polyphenol oxidase) chosen for their specific actions on polysaccharides, proteins, and phenolic compounds, respectively, fouled on a homogeneous cation-exchange membrane (referred CMX-Sb) used for tartaric stabilization of red wine by ED in industry. First, enzymatic cleaning tests were performed using each enzyme solution separately with two different concentrations (0.1 and 1.0 g/L) at different incubation temperatures (30, 35, 40, 45, and 50 °C). The evolution of membrane parameters (electrical conductivity, ion-exchange capacity, and contact angle) was determined to estimate the efficiency of the membrane′s principal action as well as its side activities. Based on these tests, we determined the optimal operating conditions for optimal recovery of the studied characteristics. Then, cleaning with three successive enzyme solutions or the use of two enzymes simultaneously in an enzyme mixture were tested taking into account the optimal conditions of their enzymatic activity (concentration, temperatures, and pH). This study led to significant results, indicating effective external and internal cleaning by the studied enzymes (a recovery of at least 25% of the electrical conductivity, 14% of the ion-exchange capacity, and 12% of the contact angle), and demonstrated the presence of possible enzyme combinations for the enhancement of the global cleaning efficiency or reducing cleaning durations. These results prove, for the first time, the applicability of enzymatic cleanings to membranes, the inertia of their action towards polymer matrix to the extent that the choice of enzymes is specific to the fouling substrates.

Highlights

Organic Fouling of ion-exchange membranes (IEMs) represents an important issue for industrials and researchers in all fields of membrane and electromembrane systems
Recent studies have demonstrated that prolonged contact with acids and bases generates significant mechanical and structural alterations of the membrane polymer matrix marked by the apparition of structure defects as well as significant membrane swelling which lead to a drop in the IEMs selectivity and performance, and reduce their life duration [4,5,9,10,11,12]
The studies the studies CEMs are not homogeneous their method of preparation and the heterogenic distribution of perfectly the organic fouling on due theirtowhole their parameters could not perfectly homogeneous due to their method of preparation andsurface, the heterogenic distribution of the heterogenic distribution of the organic fouling on their whole surface, their parameters could sensitively change from one sample to another

Summary

Introduction

Organic Fouling of ion-exchange membranes (IEMs) represents an important issue for industrials and researchers in all fields of membrane and electromembrane systems. This phenomenon concerns the deposition or the adsorption of undesirable organic matters contained in effluents and beverages treated on the surface or inside the membrane matrix. In IEMs the mechanisms involved in fouling are principally caused by electrostatic interactions between fixed functional sites of the polymer, as well as charged and ionisable molecules in solutions [1]. Recent studies have demonstrated that prolonged contact with acids and bases generates significant mechanical and structural alterations of the membrane polymer matrix marked by the apparition of structure defects as well as significant membrane swelling which lead to a drop in the IEMs selectivity and performance, and reduce their life duration [4,5,9,10,11,12]

Methods

Results

Conclusion