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Biochemical Engineering Journal
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Item-typ:Veröffentlichung, SiOC-based polymer derived-ceramic porous anodes for microbial fuel cells(Elsevier, 2019-04-29); ; ; ; The applicability of a new class of ceramic materials in Microbial Fuel Cells (MFCs) was investigated, targeting the development of cost-effective anode materials with long-term durability. In this work, silicon oxycarbide (SiOC)-based porous anodes were prepared by the polymer-derived ceramics (PDCs) route, using poly(methyl silsesquioxane) and poly(methyl phenyl silsesquioxane) as precursors while incorporating carbonaceous fillers (graphite and carbon black) and metal precursor (NiCl2). Tape casting was used in the manufacturing followed by pyrolysis at 1000 °C under nitrogen atmosphere. The interior structure and surface morphology were characterized with scanning electron microscopy (SEM), nitrogen adsorption, vapor adsorption, and contact angle measurements. The developed anodes were tested in MFC with aqueous cathode configuration using a low-cost clayware cylinder as the anodic chamber. The performance of MFC using PDC-based anodes was compared with MFC having carbon felt as anode material, which showed a two-fold increase in power density (211 and 111 mW m−2, respectively) and normalized energy recovery in former and also demonstrated chemical oxygen demand (COD) removal efficiency of about 85%. The improved performance of the PDC-based anodes is attributed to its porous structure, hydrophilic surface, and high specific surface area (39.89 m² g−1). The biocompatibility was confirmed by biofilm growth on the surfaces, while a sufficient electrical conductivity (0.10–0.18 S cm−1) makes it superior electrode material for application in MFCs.Wissenschaftlicher ArtikelBand:148111 103 - Some of the metrics are blocked by yourconsent settings
Item-typ:Veröffentlichung, Proteolytic ceramic capillary membranes for the production of peptides under flow(Elsevier, 2019-04-15); ; ; ; In this study, we investigate the effect of membrane surface functionalization on the immobilization of the protease subtilisin A and its performance in the production of peptides from the model protein casein under flow. The surface of tubular ceramic membranes was silanized to yield carboxylated and aminated supports for enzyme immobilization via non-covalent and carbodiimide activated binding. The protease density correlated with electrostatic interactions between the positively charged enzyme and the supports, with the highest enzyme density reached on negatively charged, carboxylated membranes (0.019 molecules/nm², noncovalent approach). Enzyme leaching was reduced by covalent binding of protease to carboxylated supports (5% leached) and slightly improved by binding to aminated membranes (46%) over non-covalent binding to unfunctionalized reference capillaries (66%). Regarding carbodiimide activated immobilization, protease on unfunctionalized and aminated supports exhibited a significantly larger specific activity (0.99 μmol/min/mg) than enzymes on carboxylated surfaces (0.15 μmol/min/mg), which suggests preferred enzyme orientation. In protein hydrolysis, these differences in surface-enzyme interactions were reflected by variations in peptide composition and degree of hydrolysis. Accordingly, we demonstrate that surface functionalization critically determines the surface properties of protease support materials for the production of peptides under flow and allows tailoring the performance of proteolytic capillary membranes.Wissenschaftlicher ArtikelBand:147119 100 - Some of the metrics are blocked by yourconsent settings
Item-typ:Veröffentlichung, Functionalized porous ceramic microbeads as carriers in enzymatic tandem systemsPorous Al2O3/SiO2 microbeads (MBs) are propped as carriers for enzymes used in flow reactor setups for tandem enzymatic reactions. Glucose oxidase (GOx) and catalase (CAT) perform sequential reactions. GOx catalyzes the conversion of glucose and O2 to gluconic acid and H2O2. CAT decomposes H2O2 to H2O and O2. Spherical MBs were fabricated via ionotropic gelation followed by rapid-sintering (1200 °C/5 min), featuring reasonably high open porosity (∼50%), appropriate specific surface area (30 ± 5 m2/g) and multi-modal pore sizes (d50 = 79 nm) for envisaged enzyme immobilizations. After activation and amino-silanization, GOx and CAT were successfully immobilized onto MBs applying an EDC/sulfo-NHS crosslinking reaction. Under varied pH and temperature conditions, the immobilized enzymes showed advantages towards harsh conditions (pH 2; 70 °C) and demonstrated high activities at neutral pH and 21 ± 2 °C (RT), serving as optimal conditions for flow experiments. By varying flow rates (0.1–6 ml/min) in individual reactor compartments, GOx- and CAT-functionalized MBs achieved satisfiable H2O2 conversion rates at 1.0 ml/min for 24 h. In tandem use, obtained H2O2 is constantly degraded over time, maintaining high enzymatic overall performances for two more operation cycles. The presented strategy is particularly interesting, as it can potentially be transferred to other multi-enzyme reaction systems.Wissenschaftlicher ArtikelBand:12699 113