Hollow Fiber Membrane Reactor Research Articles

A membrane reactor with two dispersion-free interfaces for homogeneous catalytic reactions

A proof-of-concept study on the use of a membrane reactor with multiple membrane bundles for carrying out homogeneous catalytic reactions was conducted. The membrane reactor operates in a plug-flow pattern with a large dispersion-free gas-catalyst interfacial area, which requires much less catalyst loading than the conventional bubble column reactors commonly used for homogeneous catalytic reactions. The multiple membrane bundles offer additional operational options by allowing the feed and product streams to be controlled separately. The advantages and operating characteristics of multiple-membrane-bundle reactors were investigated using a membrane reactor with two membrane bundles. Experimentally, the direct oxidation of ethylene to acetaldehyde in an aqueous solution of palladium(II) chloride-cupric chloride was conducted in a two-bundle polypropylene hollow fiber membrane reactor operating both as a single-bundle and as a two-bundle membrane reactor. The experimental results were successfully analyzed with a mathematical model. The results of this study provide evidence that a two-bundle membrane reactor could achieve higher conversions than a comparable single-bundle membrane reactor by controlling the flow rates of individual feed and product streams of the two-bundle membrane reactor.

Lipase kinetics: Hydrolysis of triacetin by lipase from Candida cylindracea in a hollow‐fiber membrane reactor

The aptitude of a hollow-fiber membrane reactor to determine lipase kinetics was investigated using the hydrolysis of triacetin catalyzed by lipase from Canadida cylindracea as a model system. The binding of the lipase to the membrane appears not to be very specific (surface adsorption), and probably its conformation is hardly altered by immobilization, resulting in an activity comparable to that of the enzyme in its native form. The reaction kinetics defined on the membrane surface area were found to obey Michaelis-Menten kinetics. The specific activity of the lipase in the membrane reactor was found to be significantly higher than in an emulsion reactor. The activity and stability of the enzyme immobilized on a hydrophilic membrane surface seem not to be influenced significantly by the choice of the membrane material. The hollow-fiber membrane reactor is a suitable tool to assess lipase kinetics in a fast and convenient way.

Enzymatic synthesis of n-butyl oleate in a hollow fiber membrane reactor

A new type of semi-batch membrane reactor has been developed for the synthesis of short chain alcohol fatty acid esters. The synthesis of n-butyl oleate was carried out in the reactor at a temperature of 30°C. The reaction was catalyzed by Mucor miehei lipase, which was immobilized on the membrane walls in the form of macroscopically thick ultrafiltration cake. The ester remained in the bulk phase; water, as a second product, was separated from the oil phase by diffusion through the membrane walls. At the optimal reaction mixture, with molar fraction of oleic acid of 0.55, a conversion of 88.11% was reached in a relatively short time.

A hollow‐fiber reactor design for NMR studies of microbial cells

A hollow-fiber membrane reactor was designed and constructed to allow perfusion of entrapped, dense Escherichia coli cells with nutrient medium during examination of cell metabolism using nuclear magnetic resonance (NMR) spectroscopy. Phosphorus-31 NMR spectra of the perfused cells included peaks for nucleoside di- and triphosphates, sugar phosphates, and pH-sensitive peaks for inorganic phosphate. The observed intensity of the lumenal inorganic phosphate peak was found to depend on flow rate, ruling out the use of this peak as a concentration reference. Absolute intracellular pH values obtained from NMR measurements were found to be accurate to 0.2 pH units due to uncertainties in intracellular ionic concentrations. Relative pH values, however, were found to be sensitive to cell energetic status. The response of E. coli intracellular pH following a shift to carbon starvation medium was monitored with a resolution of 3 min. Use of a hollow-fiber reactor for cell containment and perfusion during NMR spectroscopy enables metabolic experiments of longer duration and of greater variety than is possible using standard, nonperfused sample tubes.

DIRECT OXIDATION OF ETHYLENE TO ACETALDEHYDE IN A HOLLOW FIBER MEMBRANE REACTOR†

A hollow fiber membrane reactor, which resembles a tube-and-shell heat exchanger, was developed for homogeneous catalytic reactions with gas reactants and products. The gas stream flows through the...

Automated precolumn derivatization of amino acids with ortho-phthalaldehyde using a hollow-fibre membrane reactor

An automated precolumn derivatization procedure was developed for the determination of amino acids, involving the reaction of amino acids with o-phthalaldehyde (OPA) and 2-mercaptoethanol using a cation-exchange hollow-fibre membrane reactor, which is immersed in the reagent solution, and a trap column. Column switching is used to transfer OPA-amino acid derivatives from the trap column to an analytical C 18 column, and the derivatives are subjected to gradient elution and fluorimetric detection. The detection limit is 0.3–2 pmol for each amino acid. For 20 pmol of amino acids, the precision is 0.9–5.0% (relative standard deviation, n = 5). The determination of amino acids in a protein hydrolysate sample is described.

Simultaneous determination of ampicillin and sulbactam by liquid chromatography: post-column reaction with sodium hydroxide and sodium hypochlorite using an active hollow-fibre membrane reactor

A high-performance liquid chromatographic method has been developed for the simultaneous determination of ampicillin (ABPC) and sulbactam (SBT) in serum and urine. The method involves separation of ABPC and SBT from the background components of serum and urine on a C 18 column, post-column reaction with sodium hydroxide and sodium hypochlorite using an active hollow-fibre membrane reactor, and detection at 270 nm. At ABPC and SBT concentrations of 10 and 5 μg/ml in urine and serum samples, the precisions (relative standard deviations) were 0.9–2.5% ( n = 8). The detection limits were 20 and 5 ng for ABPC and SBT, respectively, at a signal-to-noise ratio of 3.

Liquid chromatographic determination of amino acids using a hollow-fiber membrane reactor

A high-performance liquid chromatographic method using a passive hollow-fiber membrane reactor (HFMR) has been developed for the determination of amino acids. This method involves gradient elution of 18 common amino acids on a C 18 column using sodium octanesulfonate as an ion-pairing agent, postcolumn derivatization with o-phthalaldehyde and 2-mercaptoethanol (combined with hypochlorite oxidation for the imino acid proline) introduced into the main flow stream using sulfonated and aminated HFMRs immersed in the reagent solutions, and fluorometric detection of derivatives ( λ ex = 340 nm, λ em = 450 nm). The detection limits of the proposed method were 0.4 to 20 pmol for each amino acid at a signal-tonoise ratio of 3. For 18 amino acids in amounts of 250–2500 pmol, the precisions were on the order of 1.5–4.8% (relative standard deviation, n = 10). The assay of amino acids in a protein hydrolysate sample by the proposed method is also described.

Liquid chromatographic determination of penicillins by postcolumn alkaline degradation using a hollow-fiber membrane reactor

A high-performance liquid chromatographic method using a hollow-fiber membrane reactor is described for the determination of penicillins. This method involves separation of penicillins on a C 18 column, postcolumn reaction with sodium hydroxide andmercury(II) chloride introduced into the main flow stream using sulfonated hollow-fiber membrane reactors immersed in each solution (4 m sodium hydroxide and 3 × 10 −2 m mercury(II) chloride plus 10 −2 m nitric acid), and detection at 290 nm based on the uv absorbance of the degradation products. At penicillin concentrations of 5 μg/ml, within- and between-run precisions (relative standard deviation) were 0.24–2.39 and 1.19–4.13%, respectively. The detection limits of the proposed method were 1–5 ng at a signal-to-noise ratio of 3. The method was applied to assays of ampicillin and its metabolites in human serum and urine.

Liquid chromatographic determination of penicillins by postcolumn degradation with sodium hypochlorite using an hollow-fibre membrane reactor

Liquid chromatographic determination of penicillins by postcolumn degradation with sodium hypochlorite using an hollow-fibre membrane reactor

Liquid chromatographic determination of penicillins by postcolumn degradation with sodium hypochlorite using an hollow-fibre membrane reactor

A sensitive, high-performance liquid chromatographic method involving postcolumn degradation with sodium hypochlorite and using a hollow-fibre membrane as a reactor is described for the determination of penicillins. Penicillins were separated on a C18 column followed by postcolumn reaction with sodium hypochlorite and sodium hydroxide using aminated and sulphonated hollow-fibre membrane reactors immersed in each solution, and detected at 270–280 nm based on the UV absorbances of the degradation products. At penicillin concentrations of 2 μg/ml, the precisions (relative standard deviation) were 2.28–4.78%. The detection limits of the proposed method were 2.5–25 ng for each penicillin at a signal-to-noise ratio of 3. Ampicillin and its metabolites [(5 R,6 R)-ampicilloic acid, the (5 S,6 R)-epimer and (2 R)-pierazine-2′,5′-dione] in human serum and urine were simultaneously determined by this method.

Sorbitol and Gluconate Production in a Hollow Fibre Membrane Reactor by Immobilized Zymomonas Mobilis

This study describes the results of a hollow fibre membrane reactor with immobilized treated cells of Zymomonas mobilis which produced sorbitol and gluconic acid continuously from fructose and glucose respectively. A productivity of 10–20 g sorbitol · L-1 · h-1 and 10–20 gluconate · L-1 · h-1 (based on total bioreactor volume) from a feed of 100 g · L-1 each of glucose and fructose was possible at high dilution rates. Kinetic parameters describing the reaction rate of treated cells in batch reactors were used to analyse the performance of the hollow fibre membrane reactor employing significant convective mass transfer. No significant mass transfer limitation was apparent.

Fluorimetric determination of amino acids by high-performance liquid chromatography using a hollow-fibre membrane reactor

A high-performance liquid chromatographic method has been developed for the determination of primary amino acids. The method involves separation of primary amino acids on a C 18 column using sodium heptanesulphonate as an ion-pairing agent, post-column derivatization with o-phthalaldehyde and 2-mercaptoethanol introduced into the main flow stream using a sulphonated hollow-fibre membrane reactor immersed in their solutions and fluorimetric detection of derivatives (λ ex = 340 nm, λ em = 450 nm). A higher or similar sensitivity was obtained compared with the conventional post-column derivatization method. The detection limits were 0.2–2.3 pmol at a signal-to-noise ratio of 3. For amounts of 48–110 pmol, the precision was of the order of 1.1–4.0% (relative standard deviation, n = 20).

Bioelectrosynthesis of halogenated compounds using chloroperoxidase

A bioelectrolytic system containing chloroperoxidase is described that chlorinates barbituric acid specifically and continuously into 5-chlorobarbituric acid. The system consists of an electrolytic cell, a hollow-fibre membrane reactor and an anion exchanger. The H 2O 2 produced in the electrolytic cell is consumed by chloroperoxidase in the membrane reactor and the product thus formed is subsequently scavenged by the anion exchanger. Besides producing H 2O 2 the electrolytic cell reverses the further enzymatic halogenation of 5-chlorobarbituric acid by dechlorination in an electro-reductive fashion.

Ethanol production by nitrogen-deficient yeast cells immobilized in a hollow-fiber membrane bioreactor

Cells ofSaccharomyces cerevisiae ATCC 4126, immobilized within the macroporous walls of asymmetric hollow-fiber membranes, were alternately perfused with 10% glucose complex medium and with 10% glucose defined medium which was deficient in nitrogen. Using complex growth medium, ethanol productivities during the initial 10 h of culture attained a maximum level of 133 g/l-h based on the total fiber volume (3% ethanol). Productivities during nitrogen deficiency stabilized at 10 g/l-h (0.5 ethanol). In subsequent growth phases, ethanol production rates increased to levels 40–70% of initial growth-phase values, but the ability to regenerate the fermentation activity decreased with culture age. During nitrogen deficiency, the fermentation efficiency declined with a concomitant reduction in the total protein concentration of immobilized cells within the hollow-fiber membranes. The molar ratio of acetaldehyde to ethanol increased seven-fold during nitrogen deficiency, indicating that the overall decline in glycolytic activity was accompanied by preferential reduction in alcohol dehydrogenase activity. The molar ratio of glycerol to ethanol increased two-fold during nitrogen deficiency, and large lipid-like droplets accumulated within the nitrogen-deficient cells. In addition to these findings, we conclude that current hollow-fiber membrane reactors should be limited to cell cultures having low growth rates, low O2 requirements, and low CO2 production rates.