Riedl, Wolfgang
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Wolfgang
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Riedl, Wolfgang
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- PublikationElectrochemical membrane-assisted pH-swing extraction and back-extraction of lactic acid(Elsevier, 2022) Riedl, Wolfgang [in: Separation and Purification Technology]Reactive extraction of carboxylic acids such as lactic acid with tertiary amines is a state-of-the-art process but suffers strongly from reduced extraction efficiency in buffered environments like fermentation broths. In order to increase the efficiency of in-situ product removal, we here propose the combination of a membrane-assisted reactive extraction with an electrochemical pH shift. Prior to extraction in the membrane module, the fermentation broth containing the lactic acid at neutral pH is treated by anodic electrolysis to reduce the pH and thereby improve the extraction yield. Additionally, the cathodic reaction is used to increase the pH of the aqueous stream used for back-extraction of the loaded organic phase. Model solutions were used to develop a mathematical model, capable of calculating the required membrane area for in-situ extractions, considering the effect of the aqueous pH on the extraction performance. Additionally, using electrochemical pH shift, we were able to concentrate lactic acid from 1 wt% in the dilute broth to 7 wt% in the back extract.01A - Beitrag in wissenschaftlicher Zeitschrift
- PublikationLiquid extraction with immobilized liquids for product recovery from fermentation broths(Elsevier, 2022) Riedl, Wolfgang [in: Innovations in fermentation and phytopharmaceutical technologies]Nowadays, many fermentation chemicals are produced at an industrial scale. Numerous technological improvements have been developed and implemented to achieve high quality and quantity of fermentation products. However, several drawbacks in fermentation processes still limit their application at an industrial level. In situ product removal (ISPR) is a potential alternative to overcome the conventional drawbacks of the fermentative processes, increasing the fermentation's productivity and reducing the separation steps for recovery and purification. Currently, liquid extraction has emerged as a promising separation technology for ISPR, with immobilized liquids such as membrane-assisted extraction and microchannel liquid membrane, due to the high mass transfer rates, scalability, easy integration, and efficiency. This chapter will discuss these technologies regarding their integration into fermentative processes.04A - Beitrag Sammelband
- PublikationMembrane-supported liquid-liquid extraction. Where do we stand today?(Wiley, 02/2021) Riedl, Wolfgang [in: ChemBioEng Reviews]Thanks to advances in materials science and manufacturing technology, membranes are now available for stable liquid-liquid extraction processes. Rigorous calculation models can be used to calculate the membrane areas required for a specific separation task as well as to optimize the module design. Rapid tests can determine the basic suitability and kinetic parameters. Thus, the general requirements for exploiting the specific advantages of this separation technology in technical applications are fulfilled.01A - Beitrag in wissenschaftlicher Zeitschrift
- PublikationMass transfer analysis and kinetic modeling for process design of countercurrent membrane supported reactive extraction of carboxylic acids(Elsevier, 2021) Riedl, Wolfgang [in: Chemical Engineering Science: X]Countercurrent membrane supported reactive extraction (MSRE) was studied for removal of carboxylic acids from aqueous streams with a PTFE capillary membrane. Analysis of the mass transfer rates was per- formed to support modeling of the process. Total mass transfer coefficients ranging from 2.0 10-7 to 4.0 10-7 m/s were obtained when extracting lactic acid with 20 wt% tri-N-octyl amine in 1-decanol with membrane thicknesses of 260 mm and 80 mm. The limiting mass transfer resistance in all experiments was in the membrane phase. The developed model based on mass transfer and reaction in parallel allows to predict countercurrent extraction. Experimental validation with 5, 7 and 12 m long membrane modules showed excellent accordance for two acids, validating the model simulations. Simulated membrane con- tactor lengths required for single, two and three countercurrent stages varied between 10 and 39 m/stage for lactic, mandelic, succinic, itaconic and citric acid, depending on acid, membrane, and diluent.01A - Beitrag in wissenschaftlicher Zeitschrift
- PublikationIn-situ recovery of carboxylic acids from fermentation broths through membrane supported reactive extraction using membrane modules with improved stability(Elsevier, 15.06.2020) Riedl, Wolfgang [in: Separation and Purification Technology]Membrane supported reactive extraction (MSE) coupled to back-extraction (MSBE) using a new type of Teflon (PTFE) capillary membrane contactor was studied for the in-situ removal of carboxylic acids from aqueous streams, e.g. fermentation broths. The use of microporous membranes as extraction interface helps avoiding emulsification problems, allows the use of extreme phase ratios, and protects microorganisms, as they are less affected by solvent toxicity during in-situ extractions. The use of PTFE capillary membranes is suitable for long-term use due its high chemical and thermal stability. A simple toxicity screening identified n-decanol with tri n-octyl amine (TOA) as a suitable solvent. MSE experiments were performed using membrane contactors (0.005 m2 to 0.15 m2), working with solvent to feed phase ratios down to 1:40 (mass based). The in-situ removal of lactic acid out of fermentation broths using lactobacillus plantarum led to a glucose conversion rate of 80 mol%. Additionally, a concentration factor up to 7.8 could be shown during back-extraction.01A - Beitrag in wissenschaftlicher Zeitschrift
- PublikationMembrane‐Assisted Liquid‐Liquid Extraction – Where Do We Stand Today?(Wiley, 29.08.2019) Riedl, Wolfgang [in: Chemie Ingenieur Technik]Dank Weiterentwicklungen in den Materialwissenschaften und der Fertigungstechnik stehen heute Membranen für stabile Flüssig/Flüssig‐Extraktionsprozesse zur Verfügung. Mit rigorosen Berechnungsmodellen lassen sich sowohl die für eine Trennaufgabe erforderlichen Membranflächen berechnen als auch Optimierungen der Modulform durchführen. In Schnelltests können die prinzipielle Eignung sowie kinetische Parameter ermittelt werden. Damit sind die Voraussetzungen geschaffen, die spezifischen Vorteile dieser Trenntechnik im technischen Einsatz nutzen zu können.01A - Beitrag in wissenschaftlicher Zeitschrift
- PublikationIndustrial Upscaling of DOPO-Based Phosphonamidates and Phosphonates Derivatives Using Cl2 Gas as a Chlorinating Agent(American Chemical Society, 10/2018) Riedl, Wolfgang [in: Organic Process Research & Development]Herein, we report the industrial synthesis procedure of phosphonamidate and phosphonate derivatives via an efficient and simple chlorination of 9,10-dihydro-9-oxa-10-phosphaphenanthren-10-oxide (DOPO) with Cl2 gas. The key step in the synthesis is the conversion of the P–H bond to P–Cl of DOPO by flowing Cl2 gas into a solution of DOPO in dichloromethane, affording the key intermediate 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-chloride (DOPO-Cl) compound which is industrially not available. DOPO-Cl was isolated, characterized, and used for this synthesis of DOPO-based phosphonamidates and phosphonates in relatively high yield by reaction with the corresponding amines and alcohols, respectively. The experimental results show that the chlorination reaction occurs in equimolar ratios of Cl2 gas to DOPO compound. Subsequently, the procedure developed in laboratory scale was industrially applied for synthesis of the 6,6′-(ethane-1,2-diylbis(azanediyl))bis(dibenzo[c,e][1,2]oxaphosphinine-6-oxide) (EDA-DOPO) compound and 6-((1-oxido-2,6,7-trioxa-1-phosphabicyclo[2.2.2]octan-4-yl)methoxy)dibenzo[c,e][1,2]oxaphosphinine-6-oxide (DOPO-PEPA). All synthetic compounds thus obtainedwere characterized and found to be identical to the authentic laboratory scale products.01A - Beitrag in wissenschaftlicher Zeitschrift
- Publikation06 - Präsentation
- Publikation06 - Präsentation
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